Synthesis and characterization of biocompatible stimuli-responsive hydrogels

Radiation curing of 1,2 epoxy – phenoxy propane in the presence of an iodonium salt

Water diffusion and swelling stresses in ionizing radiation cured epoxy matrices

Abstract In this work a DGEBF epoxy monomer was cured by electron beam radiation in the presence of an iodonium salt and the obtained system was hydrothermally aged as such and also after a thermal treatment, in order to obtain two systems having different uniformity in the cross-linking degree. On both systems, the transient stress field arising from swelling was measured and monitored by an optical Photoelastic technique and the results were commented with reference to a thermally cured epoxy system containing the same monomer and already discussed in a previous work. Beam samples with identical dimensions, obtained from the irradiated systems, have been aged at 80 °C in water, and charac…

Properties of Epoxy-Pes systems as polymer matrices for carbon fiber composites produced by e-beam curing

Photoelastic stress analysis assisted evaluation of fracture toughness in hydrothermally aged epoxies

The present work has investigated the fracture toughness of a model DGEBA epoxy system subject to Hidro-Thermal aging. A Photoelastic Stress Analysis technique has been implemented, showing the evolution of stresses arising throughout the water uptake process due to the non-uniform swelling of the material. Gravimetric and Dynamic Mechanical Thermal Analyses have further complemented the characterization, showing the onset of plasticization effects with aging. The correlation of all previous characterizations has allowed to conclude that an increase of KIC fracture toughness is obtained at the fully saturated condition. In particular Photoelasticity has also revealed the onset of relevant s…

Epoxy based matrices for structural composites prepared by ionizing radiation. Morphological and thermal behaviour

Radiation curing of epoxy resins in the presence of engineering thermoplastic: a way to produce nanostructured matrices for aerospace composites

Dynamic-mechanical and dielectric measurements have been performed with some polycarbonate samples. In one set of experiments care was taken to avoid any absorption of moisture. In other sets of experiments, samples were exposed to atmospheric humidity and to boiling water. The glass transition temperature was found to be highly affected by the absorption of water and by the test conditions. Dynamisch-mechanische und dielektrische Messungen wurden an Polycarbonatproben durchgefuhrt. In einer Versuchsserie wurde die Absorption von Wasser vollstandig vermieden, in weitern Versuchen wurden die Proben der Luftfeuchte bzw. kochendem Wasser ausgesetzt. Die Glasubergangstemperatur wurde durch das …

Electrically conductive polyaniline-hydrogel nanocompsites

Gamma radiation induced polymerization of vinyl monomers in dense CO2

Abstract The dispersion polymerization of methyl methacrylate in dense carbon dioxide, initiated by γ-rays, utilizing different polysiloxanes as polymeric stabilizers, was investigated. The progress of the reaction, as a function of the irradiation dose, was also studied and the occurrence of a gel effect has been detected. For comparison, the dispersion polymerization has been carried out in supercritical conditions ( T =65°C and 38 MPa) in the presence of 2,2′-azobis(isobutyronitrile) (AIBN) as initiator. High molecular weight polymer (M w > 1000 kg/mol) with narrow molecular weight distribution has been obtained both with γ-rays and AIBN. The electron scanning micrographs show that regul…

Radiation synthesis of nanogels as therapeutic agent vectors

Nanogels (NGs) are physically or chemically crosslinked polymer networks and are promising candidates in the development of therapeutic agent vectors. In fact, thanks to their tunable size and properties, they offer unique advantages, including a large and flexible surface for multivalent bio-conjugation, an internal 3D aqueous environment for incorporation and protection of (bio)molecular drugs, stimuliresponsiveness to achieve temporal and/or site control of the release function and biocompatibility. In order to develop effective NGs-based biomedical devices an inexpensive, robust and versatile synthetic methodology is required. In this perspective, we have produced NGs with high yields a…

Sub-micron structured Polymethyl Methacrylate/Acrylonitrile-Butadiene rubber blends obtained via gamma radiation induced “in situ” polymerisation

The morphology and properties of PMMA/rubber blends, obtained through gamma radiation induced “in situ” polymerization of methyl methacrylate (MMA) in the presence of small quantities of an acrylonitrile–butadiene based rubber (ABN), are presented. Different systems have been obtained by irradiating at a fixed irradiation dose rate and temperature, varying the integrated dose. All the blends obtained were characterized with respect to their melt state and solid state dynamic-mechanical response and mechanical tensile properties. In particular, the effect on the blend properties of prolonging the irradiation time was investigated. Furthermore, a morphological characterization through atomic …

Electrically conductive polyaniline-hydrogel composites, produced via “in situ” dispersion polymerization

Submicron structured polymethyl methacrylate/acrylonitrile-butadiene rubber blends obtained via gamma radiation induced ?in situ? polymerization

The morphology and properties of PMMA/rubber blends, obtained through gamma radiation induced “in situ” polymerization of methyl methacrylate (MMA) in the presence of small quantities of an acrylonitrile–butadiene based rubber (ABN), are presented. Different systems have been obtained by irradiating at a fixed irradiation dose rate and temperature, varying the integrated dose. All the blends obtained were characterized with respect to their melt state and solid state dynamic-mechanical response and mechanical tensile properties. In particular, the effect on the blend properties of prolonging the irradiation time was investigated. Furthermore, a morphological characterization through atomic …

Ionizing radiation induced synthesis of polymers and blends with different structures

Biocompatible nanostructured hydrogels incorporating polyaniline nanoparticles

Dielectric and dynamic-mechanical behaviour of ethylene-vinyl alcohol copolymers

Abstract Dynamic-mechanical and dielectric measurements on ethylene-vinyl alcohol copolymers with two different vinyl alcohol contents and, for comparison on polyvinylalcohol and low density polyethylene, have been carried out in order to clarify the nature of the relaxation peak. The relaxation peak observable in the dielectric loss curves of the copolymers has been assigned to the interfacial polarization, MWS type, occurring between hydrogen bonded hydroxyl groups and the apolar polyethylene segments. The shoulder also present in the e″-T curves of the copolymers seems to correspond to the glass transition peak which is hidden since the dielectric loss curve increases quickly because of …

Radiation curing of diacrylate glycerolate of bisphenol-A in the presence of an organically modified montmorillonite for the production of flame-resistant polymer–clay composites

Polymerization of an acrylate derivative of bisphenol-A by ionizing radiation in the presence of an organically modified montmorillonite was carried out in order to produce a flame-retardant composite. The measurement of the thermal effect during irradiation indicates that radiation curing of pure resin and resin-clay mixtures occurred in both cases. Moreover, differential scanning calorimetry and dynamic mechanical thermal analysis showed that a curing completion can be obtained by thermal curing after irradiation with a significant increase of the glass transition temperature. The morphology was investigated by X-ray diffraction and transmission electron microscopy. These have indicated t…

Necking behavior of low-density polyethylene-isotactic polypropylene blends: A morphological investigation

The tensile behavior of low-density polyethylene-isotactic polypropylene blends was investigated at room temperature. Neck formation and propagation along the whole length of the samples were observed for the whole range of composition. This behavior, which is not indicated by most data available in the literature, was examined in relation to sample morphology by scanning electron microscopy. The results of this investigation indicated some differences between the morphology of these materials and the morphology of blends which do not undergo necking propagation.

Effetto dell’invecchiamento idrotermico sulle proprietà termiche e meccaniche di resine epossidiche strutturali

Le resine termoindurenti, utilizzate come matrici per materiali compositi rinforzati con fibre di carbonio, sono caratterizzate da un elevato grado di densità di reticolazione che conferisce loro una elevata fragilità e che allo stesso tempo le espone a significativi effetti di invecchiamento idrotermico durante il loro utilizzo [1]. In particolare si assiste alla diminuzione della temperatura di transizione vetrosa, per effetto di fenomeni di plasticizzazione e degradazione, e alla diminuzione di modulo elastico a flessione. Recentemente gli autori hanno proposto un metodo, Photoelastic Stress Analysis (PSA), molto efficace per monitorare le modifiche del materiale, in termini di swelling …

Thermal properties of e-beam cured epoxy/thermoplastic matrices for advanced composite materials

The aim of this work is to investigate the possibility to improve the thermal behaviour of epoxy based systems, cured by ionizing radiation, in order to produce matrices for advanced carbon fibres composites. Blends of two epoxy monomers, difunctional and trifunctional, have been polymerized by e-beam irradiation and the dynamic mechanical thermal properties have been investigated. The increase of the concentration of the trifunctional epoxy monomer in the blend causes a marked increase of the Tg, but strongly decreases the reactivity. Subsequently, blends of the same epoxy monomers with a high Tg thermoplastic toughening agent have been considered and their reactivity and the thermal prope…

Grafting of Maleic Anhydride onto Isotactic Polypropylene in the Presence of Supercritical Carbon Dioxide as a Solvent and Swelling Fluid

Grafting of maleic anhydride (MA) onto isotactic polypropylene (iPP) was carried out by thermal decomposition of dicumylperoxide (DCP) using supercritical carbon dioxide (scCO2) as a solvent and swelling fluid. Provided that the initial concentration of anhydride dissolved in scCO2 is higher than 1% w/w, the grafting occurs without significant molecular weight modification of the polymer, and with a proper selection of the operative conditions, a grafting level higher than 0.5% w/w with respect to the polymer mass was obtained. The amount of grafted MA was determined by FT-IR spectroscopy and polymer degradation was monitored by dynamic mechanical tests in the melt state. The effect of MA a…

Water diffusion and swelling stresses in highly crosslinked epoxy matrices

Abstract The present work investigates the swelling induced stresses arising in two epoxy systems during water uptake. The analysed systems are two epoxy resin based on DGEBA monomer and DGEBF monomer respectively, both fully cured by DDS amine. The systems achieve different cross-link density degrees, and are characterised by high glass transition temperatures ranging between 200 and 230 °C. Both epoxies have been conditioned in deionized water baths at two different temperatures (50 °C and 80 °C). A desorption process at room temperature in a dry airborne environment was performed after saturation. Dynamic Mechanical Thermal Analysis, carried out at the various stages of hydrothermal cond…

Conductive polymer growth onto radiation grafted polyolefines

E-beam cross-linking of LDPE-OMMT nanocomposites and their photo-oxidation behaviour

Oral CorticoSteroid sparing with biologics in severe asthma: A remark of the Severe Asthma Network in Italy (SANI)

According to the data derived from several national and international registries, including SANI (Severe Asthma Network Italy), and considering the strong impact that frequent or regular use of oral corticosteroid has on quality of life (QoL) of severe asthmatics, as well as on the costs for managing corticosteroid-related diseases, oral corticosteroid sparing up to withdrawal should be considered a primary outcome in the management of severe asthma. New biologics have clearly demonstrated that this effect is possible, with concomitant reduction in the rate of exacerbations and in symptom control. Then, there is no reason for using so frequently oral corticosteroid before having explored al…

Carboxylation of a linear low density polyethylene via gamma irradiation in presence of carbon dioxide in subcritical and supercritical conditions

Abstract In this work the molecular modifications induced in a linear low density polyethylene gamma irradiated in presence of carbon dioxide both in subcritical and supercritical conditions are presented. The obtained results indicate that this process can be a new and interesting way in order to graft oxidized groups in the polyethylene chains. Moreover it is worth noting that, together with these functionalization reactions, also a significant crosslinking occurs, with improvement in some mechanical tensile behaviour.

Functionalization of a polyaspartamide with glycidyl methacrylate: A useful method to prepare hydrogels through gamma irradiation

α-β-Poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) was derivatized with glycidyl methacrylate (GMA). Aqueous solutions of the obtained copolymer PHEA-GMA (PHG) were irradiated by gamma rays with a dose rate of 0.5 KGy/h and at zero °C in the presence or in the absence of N,N'-methylenebisacrylamide (BIS). New hydrogel systems were obtained and characterized by FT-IR analyses and swelling measurements in aqueous medium at different pH values.

Compositi elettroattivi costituiti da nanoparticelle di polianilina disperse in polivinilpirrolidone

“Ionizing radiation induced polymerization of epoxy resin in order to produce carbon fibre composites”

Idrothermal ageing of ionizing radiation cured epoxy matrices for carbon fibre composites

Radiation processing per la sintesi di nuovi materiali

RADIATION-ENGINEERED NANOGELS AS GADOLINIUM VECTORS IN BIO-IMAGING

Smart hydrogels for novel optical functions

Nanocomposites of inherently conductive polyaniline (PANT) within a highly hydrophilic polyvinyl alcohol (PVA) based hydrogel have been produced by coupling a conventional dispersion chemical oxidative polymerization to a subsequent high energy irradiation step, in order to convert the polymer stabilizing the aqueous dispersion, namely the PVA, into a highly water swollen hydrogel incorporating the PANT particles. The incorporation of the electroactive and "pH-sensitive" polymer into a transparent and highly permeable hydrogel matrix has been pursued as a route to the development of a novel class of potentially biocompatible, smart hydrogels that can respond to changes of the surrounding en…

DELAMINAZIONE INTERLAMINARE DI COMPOSITI CFRP AL VARIARE DELLE CONDIZIONI DI CURA DELLA MATRICE

In questo lavoro si è condotto uno studio sperimentale del comportamento a delaminazione interlaminare in Modo I di laminati compositi unidirezionali in fibra di carbonio e matrice epossidica (CFRP), al variare delle condizioni di cura della matrice. Tutti i sistemi analizzati hanno utilizzato lo stesso tessuto e lo stesso monomero epossidico DGEBA. Variando il processo di cura (cura termica o mediante radiazioni), gli agenti di cura (ammine o anidridi per i sistemi curati termicamente), e l’impiego di additivi tenacizzanti (es. il PES per i sistemi irradiati), è stato possibile controllare e modificare sia il grado di adesione fibra/matrice, che il grado di fragilità della matrice (monitor…

Realizzazione di Giunti Strutturali Mediante Polimerizzazione di Sistemi Adesivi Indotta da Fasci di Elettroni

Absorption kinetics and swelling stresses in hydrothermally aged epoxies investigated by photoelastic image analysis

Abstract The present work proposes an experimental optical methodology able to measure the transient swelling stresses induced by the water uptake ageing of polymers. In particular, the work describes the implementation of a Photoelastic technique to quantify internal stresses arising during the hydrothermal ageing of cast epoxy samples. The material investigated is a model DGEBA/DDS epoxy system. Curing and post-curing cycles have been optimised in order to obtain a fully cured, high T g , and completely stress free initial condition. Rectangular beam samples were then left in a hydrothermal bath at 90 °C, and regularly monitored by gravimetric and photoelastic analyses. The quantitative e…

Radiation engineered functionalized nanogels as platform for biomedical nanocarriers

Optical properties of biocompatible polyaniline nano-composites

Abstract Polyaniline (PANI) is an electro-active polymer of great interest thanks to its outstanding physical and chemical properties which make it suitable for various applications in optics, bioelectronics, biosensors, diagnostics and therapeutic devices. Unfortunately, PANI is infusible and insoluble in most common solvents and, thus, very difficult to process. In the attempt of improving processability, yet preserving its interesting properties, PANI has been synthesized in the form of particles and dispersed into a hydrogel matrix. The synthesis of PANI–hydrogel composites proceeds via γ-irradiation of PANI dispersions as obtained by ‘in situ’ polymerization of aniline in the presence …

Insulin Nanogels: a New Strategy for the Treatment of Alzheimer’s Disease

A growing body of evidence shows that Insulin, Insulin Receptor (IR) and IR signaling are involved in brain cognitive functions and their dysfunction is implicated in Alzheimer’s disease (AD) degeneration. Thus, administration of insulin could be a strategy for AD treatment. For this aim we have designed, synthesized and characterized a nanogel system (NG) to deliver insulin to the brain, as a tool for the development of a new therapy for AD. A carboxyl-functionalized poly(N-vinyl pyrrolidone) nanogel system produced by ionizing radiation was chosen as substrate for the covalent attachment of insulin or fluorescent molecules relevant for its characterization. Biocompatibility of the naked c…

Toughened epoxy matrices produced by e-beam irradiation

Deformation recovery behavior of a solid polymer after tensile yielding

In this work the deformation recovery behavior of an amorphous polymer after large tensile deformation is studied at different temperatures. The effect of three parameters other than temperature has been pointed out in previous works (1–3).

Radiation processing: an alternative and environmentally friendly way to produce advanced Materials. Synthesis of PANI/hydrogels composites

Processi di cura di resine epossidiche mediante radiazioni ionizzanti per la realizzazione si materiali compositi per il settore aerospaziale. Influenza delle condizioni operative sulle proprietà finali

Influence of Nylon 6,6 nanofiber mats on cure behavior and properties of CFR epoxy resin

In this work Nylon 6,6 nanofibrous mats produced by electrospinning were used as interlayers in carbon fiber reinforced laminates. A high crossilinked epoxy resin was chosen as matrix. The effects of polymeric mats on cure behavior, thermal and delamination properties of the composite laminates were investigated.

Inverse response of polypropylene to gamma radiation under vacuum

Abstract The effect of gamma radiation under vacuum on polypropylene is analysed on the basis of a simple kinetic model. The influence of the irradiation parameters, total absorbed dose and dose rate, on the rates of the main reactions occurring during irradiation, i.e. β-scission, addition to double bonds and termination, is studied. Using kinetic equations, and free radical and double bond balance relationships, we show that it is possible to rationalize the response of polypropylene to gamma radiation. In particular, on the basis of the mathematical solutions of these equations, we obtain the equation of an ‘inversion curve’, implicit function of the irradiation parameters, which gives t…

Radiation engineered nanogels as platform for next-generation of medical diagnostics and therapeutics

Gamma radiation of EVA-AA/MMA swollen systems to obtain mechanically improved blends

In this work a "new" way to obtain "compatibilised" blends of rubber-glassy thermoplastic components is presented. Polyethylen-vinyl acetate acrylic acid terpolymer is swollen by methylmetacrylate and the system is irradiated through gamma rays in order to induce polymerisation of the monomer. Solubility and dynamic mechanical tests indicate the formation of a two phase system, even though in presence of strong interactions between the two components. Mechanical tensile behaviour is that of a ductile material with appreciable modulus values.

The durability of carbon fiber/epoxy composites under hydrothermal ageing

Studies on fibre reinforced composites are now receiving greater attention. Industrial applications have been successful in areas like aerospace, automobile, marine, construction and sporting goods. The first generation of epoxy resins for use in carbon fibre composites are able to achieve optimized high stiffness modules and high heat resistance by a high crosslink density, reached through thermal curing. However, these formulations can be very toxic and brittle with low crack resistance, which was a major disadvantage for structural applications. In the last years the use of ionizing radiation as alternative to thermal curing has been proposed as an environmentally friendly process. Furth…

Electric properties of gamma-crosslinked hydrogels incorporating organic conducting polymers

Molecular modifications—Mechanical behaviour relationships for gamma irradiated LLDPE/PA6 blends

Abstract The molecular modifications, due to γ radiation under vacuum, of linear low density polyethylene/polyamide 6 blends are presented and related to their mechanical behaviour. Solubility and melt viscosity tests indicate that in blends the polyethylene component undergoes mainly crosslinking phenomena, whereas the main effect on polyamide is chain branching. According to these molecular modifications, the most relevant effect is the increase of the tensile modulus for the polyethylene rich blends and the increase of the impact strength for the polyamide rich blends.

Electrically conductive hydrogel composites made of polyaniline nanoparticles and poly(N-vinyl-2 pyrrolidone)

Electrically conductive polyaniline-hydrogel nanocomposites

Physical and structural characterization of blends made with polyamide 6 and gamma-irradiated polyethylenes

Abstract Morphological, calorimetric and rheological results of blends made with polyamide 6 and polyethylene gamma irradiated in air are presented. The polar oxidized groups grafted in the poliolefin chains through gamma-radiation induce “compatibilization” effects in the blends with a more uniform and finer distribution of the polyethylene “phase” in the polyamide matrix, with respect to blends made with the unirradiated polymer. This effect, observed with polyethylenes of different molecular structure, i.e. low density, linear low density and high density, was attributed to the presence of interactions among the functional oxidized groups of the polyethylene chains and the polyamide. Tes…

Interlaminar fracture toughness behavior of electron-beam cured carbon-fiber reinforced epoxy-resin composites

The work describes the preparation and physical-mechanical characterization of unidirectional CFRP panels manufactured by an electron beam curing technique. Delamination fracture toughness in Mode I and II is investigated in order to evaluate the influence of fiber–matrix adhesion strength, matrix toughness and matrix crosslinking density as determined by the radiation curing process. A matrix system comprising a DGEBA epoxy monomer and an initiator of cationic polymerization have been used, with one batch of resin mixed with a PES monomer in order to enhance matrix toughness. Curing was achieved with a pulsed 10 MeV Electron Beam accelerator. Thermally cured composite systems have also bee…

The influence of the processing temperature on gamma curing of epoxy resins for advanced composites

Synthesis and characterization of biocompatible responsive hydrogels

Radiation curing of an epoxy resin based system under controlled temperature conditions

Hydrogel Nanocomposites Containing Polyaniline With Different Morphologies for Possible Bioengineering Applications

Study of the curing of a DGEBA based system through structural investigation

The Severe Asthma Network in Italy: Findings and Perspectives

Background Severe Asthma Network in Italy (SANI) is a registry of patients recruited by accredited centers on severe asthma. Objective To analyze epidemiological, clinical, inflammatory, functional, and treatment characteristics of severe asthmatics from the SANI registry. Methods All consecutive patients with severe asthma were included into the registry, without exclusion criteria to have real-life data on demographics, asthma control, treatments (including biologics), inflammatory biomarkers, and comorbidities. Results A total of 437 patients (mean age: 54.1 years, 57.2% females, 70.7% atopics, 94.5% in Global Initiative for Asthma severity step V) were enrolled into the study. The mean …

Radiation curing of carbon fibre composites

Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides…

Macro-oriented network of liquid-crystalline polyesters: crosslinking induced by g-irradiation and thermally activated reaction.

Abstract The synthesis of a macro-oriented network from liquid-crystalline polymers, bearing pendant groups with unsaturations, is reported. Virgin polymers are processable to obtain oriented samples, e.g. fibres, which may be crosslinked through thermal activation and/or exposure to γ-radiation. The liquid-crystalline state is “frozen” and the macroscopic anisotropy is preserved even at high temperatures. Compared to virgin fibres, irradiated samples show an enhancement of tensile performances, thus indicating that the main effect of irradiation is crosslinking without significant degradation phenomena.

E-beam crosslinked, biocompatible functional hydrogels incorporating polyaniline nanoparticles

Abstract PANI aqueous nanocolloids in their acid-doped, inherently conductive form were synthesised by means of suitable water soluble polymers used as stabilisers. In particular, poly(vinyl alcohol) (PVA) or chitosan (CT) was used to stabilise PANI nanoparticles, thus preventing PANI precipitation during synthesis and upon storage. Subsequently, e-beam irradiation of the PANI dispersions has been performed with a 12 MeV Linac accelerator. PVA-PANI nanocolloid has been transformed into a PVA-PANI hydrogel nanocomposite by radiation induced crosslinking of PVA. CT-PANI nanoparticles dispersion, in turn, was added to PVA to obtain wall-to-wall gels, as chitosan mainly undergoes chain scission…

Blends of polyamide 6 and linear low density polyethylene functionalized with methacrylic acid derivatives

Abstract Morphological, calorimetric, rheological, dielectric and mechanical behaviour of blends made with polyamide 6 (PA6) and linear low density polyethylene (PE) are presented. The PE was functionalized grafting ester and alcohol groups in a Brabender mixer with methacrylic acid derivatives. These groups induce “compatibilization” effects in the blends with respect to blends made with the unfunctionalized polyethylene. The difference effects on the behaviour of the blends of the various functional groups are shown. In particular, the interactions at the interface change depending on the chemical nature of the grafted groups. Ethyl and isobuthyl-methacrylate essentially cause dipolar int…

Radiation Curing of Thermosetting- Thermoplastic Blends as Matrices for Structural Carbon Fibre Composites

Nano-structured soft composites: materials for an interactive interface between human and the environment

Synthesis od epoxy/carbon fiber composites induced by e-beam. Study of the effect of hydrothermal ageing on thermal and mechanical properties

Hydrogels containing 5-Fluorouracil obtained by γ-irradiation. Synthesis, characterization and in vitro release studies

The functionalization of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide (PHEA) with glycidyl methacrylate (GMA) gives rise to a water-soluble copolymer PHEA-GMA (PHG) containing double bonds and ester groups in the side chain. Aqueous solutions of PHG alone or in combination with N,N′ methylenbisacrylamide (BIS) have been exposed to a γ-ray source at different irradiation doses in order to obtain polymeric networks. All samples have been prepared both as water-swellable microparticles and as gel systems. Microparticles have been characterized by FT-IR spectrophotometry and swelling measurements in aqueous media mimicking biological fluids. The effect of irradiation dose and BIS presence on rheol…

Radiation sculpured nanogels as platform for novel therapeutic systems

Multifunctional and Bio-hybrid Hydrogel As bioartificial Matrices and Drug Delivery Devices

Accelerated ageing due to moisture absorption of thermally cured epoxy resin/polyethersulphone blends. Thermal, mechanical and morphological behaviour

Abstract A model epoxy resin/anhydride system, modified with a polyethersulfone (PES) engineering thermoplastic toughening agent, has been studied under hydrothermal ageing in order to investigate the modification of the thermal, morphological and mechanical behaviour through dynamical mechanical thermal analysis, SEM microscopy and fracture toughness test respectively. Two different concentrations of the toughening agent were used in the blends and two ageing conditions have been considered, consisting of the immersion of the samples in distilled water at constant temperature of 70 °C for 1 week and for 1 month. Dynamical mechanical thermal analysis results on hydrothermally aged materials…

Advances in Conductive Polymers/Hydrogel Nanocomposites

Water-borne e-beam crosslinked nanogels as nanomaterials platform for drug delivery

RADIATION CURING OF CARBON FIBRE COMPOSITES

Structure and properties of nylon 6 modified by ?-irradiated linear low density polyethylene

In this work, structure and properties of blends of nylon 6 with 10% linear low density polyethylene γ-irradiated in air at different integrated doses are presented. More particularly, Molau tests, DSC, SEM, and mechanical tests have been performed. Results show that positive morphological changes with respect to the blend with unirradiated linear low density polyethylene are well evident, especially in the blend with polyethylene irradiated at 50 KGy. This blend also shows an enhancement of the elongation at break and of the impact properties.

Nano structured systems synthesised by ionizing radiation

Radiation curing per la realizzazione di materiali compositi avanzati

Nanostructured soft composites for an interactive interface between Human and the environment

The effect of the composition on the properties of?-irradiated ethylenevinyl alcohol copolymers

Two ethylene-vinyl alcohol copolymers (Eval E and Eval F with about 45% and 25% of ethylene respectively) have been irradiated in air in the dose range 0–200 Mrad. The irradiated samples show both crosslinking and degradation; the former effect is more relevant in the copolymer with a larger content of polyethylene. Calorimetric results show that both the crystalline and the amorphous phases are involved in the reactions initiated by the irradiation.

Mode I fracture toughness behavior of hydro-thermally aged carbon fibre reinforced DGEBA-HHPA-PES systems

In this work the Mode I fracture toughness behavior of unidirectional CFRP laminates is investigated by means of Double Cantilever Beam (DCB) tests. The composite samples were manufactured by thermal curing after impregnation of a Carbon fabric with a DGEBA epoxy and anhydride HHPA curing agent. One resin batch was also mixed with a PES thermoplastic monomer to enhance the matrix toughness. Two lots of samples, toughened and un-toughened, were then left to soak in hot water to achieve various degrees of aging. The influence of matrix toughening and hydrothermal aging on the delamination behavior of the composite have then been assessed and correlated with characterization data from Dynamic …

Properties-morpholohy-processing relationships in the e-beam curing of epoxy resin-thermoplastic blends for advanced composite matrices

Synthesis and characterization of water-swellable?,?-polyasparthydrazide derivatives

α, β-polyasparthydrazide (PAHy) was crosslinked by glutaraldehyde to form water-swellable materials possessing a three-dimensional molecular network. Different crosslinking degrees were prepared varying glutaraldehyde/PAHy ratio and samples containing 5-fluorouracil were obtained by incorporating the drug into the polymer networks during the crosslinking reaction. All samples were characterized by swelling tests, thermal, x-ray and SEM analysis. Their microstructure was observed through scanning electron microscopy. Furthermore, for samples containing the anticancer drug,in vitro release studies were performed in pH 7.4 buffer solution.

Probing the internal environment of PVP networks generated by irradiation with different sources

Poly(N-vinyl-2-pyrrolidone) (PVP) hydrogels have been synthesised from the aqueous solutions of the same linear polymer by two different radiation sources: electron beams and UV rays. The present investigation couples conventional hydrogel characterisation techniques with the study of the partition equilibria, fluorescence behaviour and release of two different molecular probes, 1-anilino-8-naphthalene sulphonate (ANS) and Thioflavin T (ThT). The two probes have comparable molecular weight and different structural and optical properties. The ‘chemical’ networks produced upon irradiation in different experimental conditions presented quite distinctive mechanical spectra, yielded to different…

E-Beam Crosslinked Polymeric and Bio-Hybrid Nanocarriers for Drug Delivery and Bioimaging

Irradiation of low density and high density polyethylenes in presence of carbon dioxide in subcritical and supercritical conditions

Abstract The grafting of carboxylated and oxygenated functions on low density and high density polyethylenes is carried out by gamma irradiation in the presence of carbon dioxide. Both crosslinking and grafting of oxidised groups occur. The extent of these molecular modifications depends on the physical conditions of the gas phase and on the nature of the polymer matrix.

Thermal and mechanical properties of polymer matrices for carbon fibre composites produced by radiation curing of Epoxy-Pes blends

Synthesis, characterisation and properties of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide-graft-maleic anhydride precursors and their stimuli-responsive hydrogels

Abstract A family of poly(amino acid)-maleic anhydride hydrogels were designed and synthesized. Water soluble polymeric precursors were prepared by partially substituting the hydroxyl groups of the α,β-poly( N -2-hydroxyethyl)- dl -aspartamide backbone with maleic anhydride, so as to provide double bonds for crosslinking and carboxylic acid groups for pH and electric field responsiveness. Reaction conditions (reactive mixture composition and catalysis) were systematically varied in order to obtain PHEA–MA precursors with different and reliable graft-maleic anhydride levels. PHEA–MA precursors were characterised by titration, Nuclear Magnetic Resonance ( 1 H NMR), Fourier-Transformed Infrare…

Polymer matrices for composites obtained through radiation curing of epoxy resins

Effectiveness of benralizumab in severe eosinophilic asthma: Distinct sub-phenotypes of response identified by cluster analysis

Background: Benralizumab is effective in severe eosinophilic asthma (SEA), but suboptimal responses are observed in some patients. Although several factors have been associated with benralizumab response, no cluster analysis has yet been undertaken to identify different responsiveness sub-phenotypes. Objective: To identify SEA sub-phenotypes with differential responsiveness to benralizumab. Methods: One hundred and five patients diagnosed with SEA who had completed 6 months of benralizumab treatment were included in a hierarchical cluster analysis based on a set of clinical variables that can be easily collected in routine practice (age, age at disease onset, disease length, allergen sensit…

Macromolecular engineering of hydrogels: from macro to nano scalar materials for different levels of biointeraction

Hydrogel films engineered in a mesoscopically ordered structure and responsive to ethanol vapors

Abstract Responsive hydrogels filling the interstitial spaces of photonic crystals can form mesoscopically structured materials, which exhibit reversible shifts in the Bragg diffracted light as a response of environmental changes. These materials can be used to generate chemical or biochemical sensors. The present work reports on the synthesis and characterization of ethanol responsive hydrogels that can be used in the design of novel breathalyzers. The dynamic mechanical behavior of the macroscopic hydrogels and their swelling features in the presence of different liquids or vapors have been investigated to orientate the choice of the best responsive material and curing process. The swelli…

Matrici polimeriche nanostrutturate per materiali compositi ottenute mediante radiazioni ionizzanti

Advances in Conducting Polymers/hydrogel Nanocomposites

High energy radiation processing for the synthesis of insulin nanocarriers for the development of a new strategy for the treatment of Alzheimer's Disease

Nanogels are nanoscalar polymeric networks, characterized by a dynamic internal structure and a flexible adaptive shape. When they are used as drug carriers, their flexibility and shape changing ability can facilitate the bypass of biological barriers, ensure protection of the payload and enable interaction of any attached ligand with its receptors. Poly(N-vinyl pyrrolidone)-co-acrylic acid nanogels (NGs) have been produced by ebeam irradiation of diluted aqueous solutions of a water-soluble polymer in the presence of a small amount of acrylic acid. In particular, industrial accelerators and the typical set-ups and doses applied for sterilization have been used. [1, 2] Particle size, molecu…

Ionizing radiation induced curing of epoxy resin based systems for advanced composites matrices

Effect of irradiation temperature and dose rate on the mechanical tensile behaviour of low density polyethylene

Abstract The effect of ageing due to gamma radiation, at various dose rates and temperatures, on the mechanical tensile behaviour of low density polyethylene is studied. In order to detect synergistic effects, tensile tests on samples subjected to thermal treatment corresponding to the same temperature for the same time as for the irradiation tests have also been performed. The results indicate a generalized decrease of the elongation at break, with brittleness of the material for the most severe ageing treatments. For modulus values, an increase is observed for particular experimental conditions. These results are related to morphological and structural modifications induced in the polymer…

High-energy radiation processing, a smart approach to obtain PVP-graft-AA nanogels

Abstract Poly(N-vinylpyrrolidone)-grafted-acrylic acid biocompatible nanogels (NGs) were prepared using an exiting industrial-type electron accelerator and setups, starting from semi-dilute aqueous solutions of a commercial PVP and the acrylic acid monomer. As a result, NGs with tunable size and structure can be obtained quantitatively. Sterility was also imparted at the integrated dose absorbed. The chemical structure of the NGs produced was confirmed through Fourier Transformer Infrared Spectroscopy (FT-IR). The molecular and physico-chemical properties of NGs, such as the hydrodynamic dimensions and surface charge densities, for various polymer and monomer concentrations in the irradiate…

Onset of effect and impact on health-related quality of life, exacerbation rate, lung function, and nasal polyposis symptoms for patients with severe eosinophilic asthma treated with benralizumab (ANDHI): a randomised, controlled, phase 3b trial

Background: ANDHI was done to assess the efficacy of benralizumab, including onset of effect and impact on health-related quality of life (HRQOL), exacerbation rate, lung function, and nasal polyposis symptoms. Methods: This phase 3b, randomised, double-blind, parallel-group, placebo-controlled ANDHI study was completed in adults (aged 18–75 years) with severe eosinophilic asthma with at least 2 exacerbations in the previous year, despite high-dose inhaled corticosteroid plus additional controllers, screening blood eosinophil counts of at least 150 cells per μL, and an Asthma Control Questionnaire 6 (ACQ-6) score of 1·5 or more. Patients who met eligibility criteria were randomly assigned (…

The influence of the processing temperature on gamma curing of epoxy resins for the production of advanced composites

Abstract Gamma radiation curing of an epoxy monomer, in the presence of an iodonium salt, as initiator, is studied. Systems have been polymerized at the same irradiation dose and dose rate and at different processing temperatures. The experimental results show that all the irradiated materials exhibit a latent reactivity, undergoing toward an increase of crosslinking density if they are thermally cured after irradiation. The results indicate that the processing temperature affects both the crosslinking density after irradiation and the sensibility to the post-irradiation thermal treatment.

Large-scale radiation manufacturing of hierarchically assembled nanogels

Nanogels (NGs), or small particles formed by physically or chemically crosslinked polymer networks, represent a niche in the development of "smart" nanoparticles for drug delivery and diagnostics. They offer unique advantages over other systems, including a large and flexible surface for multivalent bio-conjugation; an internal 3D aqueous environment for incorporation and protection of (bio)molecular drugs; the possibility to entrap active metal or mineral cores for imaging or phototherapeutic purposes; stimuli-responsiveness to achieve temporal and/or site control of the release function and biocompatibility. The availability of inexpensive and robust preparation methodologies is at the ba…

POLYSACCHARIDE-BASED HYDROGELS FOR MYOCARDIUM REMODELING

Structural modifications in an irradiated ethylene-vinyl alcohol copolymer

Extraction experiments and calorimetric measurements have been performed, on a commercial ethylene-vinyl alcohol copolymer irradiated in the dose range 0–20 Mrad.

Idrogeli a base di xyloglucano per la produzione di medicazioni avanzate nel trattamento delle ferite

In questo lavoro sono stati preparati film sottili di idrogelo (reticolati fisicamente o chimicamente) a base di xyloglucano (XG) e XG/polivinilalcol (PVA), a cui si è aggiunto glicerolo come plasticizzante. Lo xyloglucano è un polisaccaride di origine vegetale, caratterizzato da una catena principale di (1,4)--Dglucosio con ramificazioni laterali di (1-6)-α-xilosio, parzialmente sostituite con (1-2)–β galattosio. E’ stata indagata la possibilità di modulare la densità di reticolazione dell’idrogelo per ottenere il miglior compromesso tra resistenza meccanica e flessibilità, l’integrità strutturale nel tempo e la capacità di assorbire fluidi biologici o trattenere l’umidità. Inoltre, ne è …

Electron beam induced polymerisation of MMA in the presence of rubber: a novel process to produce tough materials

Abstract PMMA-rubber blends are formed through electron beam induced in situ polymerisation. The influence of rubber nature and irradiation dose has been investigated through mechanical tensile tests, solubility analysis and the results were related to material structure investigated through atomic force microscopy. Some blend formulations present a significant increase of ductility with respect to pure PMMA, without a dramatic decrease of modulus, yield stress and stress at break values. The results are interpreted on the basis of the criterion of the critical inter-particle thickness.

Microgels of polyaspartamide and poly(ethylene glycol) derivatives obtained by γ-irradiation

Abstract The copolymer PHG based on α , β -poly( N -2-hydroxyethyl)- dl -aspartamide (PHEA) functionalized with glycidyl methacrylate has been exposed in aqueous solution to a γ -ray source at different irradiation doses (2, 2.5 and 3.5 kGy), alone or in combination with poly(ethylene glycol)dimethacrylate (PEGDMA) or poly(ethylene glycol)diacrylate (PEGDA). The irradiation produces microgel systems that have been characterized by viscosity measurements. Lyophilization of microgels gives rise to samples able to swell instantaneously in water whereas their treatment with acetone produces swellable microparticles that have been characterized.

Polymerization of methyl methacrylate through ionizing radiation in CO2-based dense systems

Herein, we report the use of ionizing radiation to induce a dispersion polymerization reaction in dense CO2. As a model system, the polymerization of methyl methacrylate in the presence of poly(dimethylsiloxane) stabilizers was investigated. It was demonstrated that the dose plays the key role in the progress of the reaction and in the morphology of the resulting polymer. Dispersion polymerization carried out in the presence of mono- and bifunctionalized surfactants gave differently structured polymers. The polymers obtained have been characterized by scanning electron microscopy, solubility tests, and gel permeation chromatography, and the molecular structure has been related to dynamic me…

Pulsatile protein release and protection using radiation-crosslinked polypeptide hydrogel delivery devices

Abstract In the recent years recombinant technology has identified numerous protein based therapeutics. Their effective delivery, though, can be challenging due to the poor stability of most proteins along their pathway to the target site in the body. Hydrogels have been identified as good candidates for protein encapsulation and delivery thanks to both material and manufacturing process advantages. In this work we propose high energy irradiation as a synthetic methodology of choice to engineer hydrogel-based delivery devices for encapsulation and pulsatile release of proteins, triggered by pH, and for prevention of their denaturation when encapsulated. In particular, maleic anhydride funct…

Benralizumab Effectiveness in Severe Eosinophilic Asthma with and without Chronic Rhinosinusitis with Nasal Polyps: A Real-World Multicenter Study

Background: Chronic rhinosinusitis with nasal polyps (CRSwNP) affects around 60% of patients with severe eosinophilic asthma (SEA). Benralizumab was recently approved for SEA add-on treatment. Objective: To assess the real-world effectiveness of benralizumab in SEA with or without CRSwNP. Methods: We conducted a multicenter observational study, including patients with SEA treated with benralizumab for 24 weeks in 12 Italian specialized facilities. Asthma exacerbations, Asthma Control Test (ACT), lung function, oral corticosteroid (OCS) dosage, and eosinophil and basophil count in peripheral blood were recorded at baseline and after 4, 12, and 24 weeks. The 22-item Sino-Nasal Outcome Test (S…

Electrically conductive hydrogel composites made of polyaniline nanoparticles and poly(N-vinyl-2-pyrrolidone)

Abstract A novel electrically conductive composite material, consisting of polyaniline (PANI) nanoparticles dispersed in a polyvinyl pyrrolidone (PVP) hydrogel, was prepared ‘in situ’ by water dispersion polymerisation (DP) of aniline using PVP as steric stabiliser, followed by γ-irradiation induced crosslinking of the PVP component. Conversion yield of aniline into PANI particles was determined via HPLC and gas chromatography, while structural confirmation of the synthesised polymer was sought by FTIR. Morphology and dimensions of PANI particles into the coloured, optically transparent hydrogel was determined by electronic microscopy; moreover, swelling behaviour of composite hydrogels in …

Hydrothermal ageing of radiation cured epoxy resin-polyether sulfone blends as matrices for structural composites

Abstract The hydrothermal ageing of epoxy–thermoplastic blends, used as matrices for carbon fibre composites, cured by electron beam, has been studied. Two different thermoplastic percentages have been adopted. A suitable choice of both curing process and formulation parameters allows to carry out irradiation at mild temperature with several advantages, coming from a “non thermal” process, for both the final properties of the materials and the environment. Nevertheless the occurring of vitrification phenomena needs the use of a short thermal treatment after irradiation on the already solid materials, in order to complete the cure reactions. Radiation cured epoxy based matrices have been sub…

The electrochemistry of carbon monoxide reductive cyclotetramerization to squarate anion

Abstract The electrochemical reduction, of carbon monoxide to C4O2−4 squarate anion is investigated. Particular attention is devoted to the influence that solvents, electrolytes, electrodes and carbon monoxide pressure have on the yields. The main feature appears to be that strictly controlled conditions are not necessary for cyclotetramerization. In dmf — Bu4NBr the following yields vs reacted CO and circulated charge were obtained with different cathodes: Pt(49%, 34%); Au(48%, 29%); Al(47%, 38%); stainless steel (36%, 33%); graphite (39%, 31%). A distinct influence of the supporting electrolyte (inorganic and tetraalkylammonium halides) was however observed.

Water diffusion and swelling stresses in ionizing radiation cured epoxies as matrices for carbon fiber composites

Cross-linking polymerization initiated by high energy radiation is a very attractive technique for the production of high performance composite materials. This method in fact offers many advantages compared to conventional thermal curing processes, due to the possibility to operate at mild temperature and in short time, limiting both energy and time consuming [1-2]. High performance composite materials mainly consist of epoxy resins as matrix and carbon fibers as reinforce, due to their excellent properties in terms of thermal and mechanical resistance. An important requirement of such systems for structural applications is their ability to maintain the properties within a fixed range durin…

Insulin Nanogel as New Strategy for the Treatment of Alzheimer’s Disease

A growing body of evidence shows that Insulin, Insulin Receptor (IR) and IR signaling are involved in brain cognitive functions and their dysfunction is implicated in neuronal degeneration associated with Alzheimer's disease (AD). Thus, the administration of insulin to the brain could be a strategy for the prevention and treatment of AD disease. With this aim, we have designed, synthesized and characterized a nanogel system (NG) that can be used as substrate for the conjugation of insulin and/or fluorescent molecules relevant for their characterization. In particular, a carboxyl-functionalized poly(N-vinyl pyrrolidone) nanogel system, has been produced by ionizing radiation starting from th…

Optically active and biocompatible polyaniline nanoparticles - hydrogel composites.

Functional hydrogels containing polyaniline nanoparticles through e-beam irradiation

Severe asthma: One disease and multiple definitions

Abstract Introduction There is, so far, no universal definition of severe asthma. This definition usually relies on: number of exacerbations, inhaled therapy, need for oral corticosteroids, and respiratory function. The use of such parameters varies in the different definitions used. Thus, according to the parameters chosen, each patient may result in having severe asthma or not. The aim of this study was to evaluate how the choice of a specific definition of severe asthma can change the allocation of patients. Methods Data collected from the Severe Asthma Network Italy (SANI) registry were analyzed. All the patients included were then reclassified according to the definitions of U-BIOPRED,…

Large-scale Radiation Manufacturing of Hierarchically Assembled Nanogels

Nanogels (NGs), or small particles formed by physically or chemically crosslinked polymer networks, represent a niche in the development of “smart” nanoparticles for drug delivery and diagnostics. They offer unique advantages over other systems, including a large and flexible surface for multivalent bio-conjugation; an internal 3D aqueous environment for incorporation and protection of (bio)molecular drugs; the possibility to entrap active metal or mineral cores for imaging or phototherapeutic purposes; stimuli-responsiveness to achieve temporal and/or site control of the release function and biocompatibility. The availability of inexpensive and robust preparation methodologies is at the ba…

Macromolecular design and preparation of nanogels as pharmaceutical carriers

Internal properties of "ultra clean" hydrogels synthesized via e-beam irradiation through absorption and luminescence spectroscopy

TEMPERATURE-TRIGGERED MACROSCOPIC GELATION OF IRRADIATED XYLOGLUCANS FOR BIOMEDICAL APPLICATIONS

Structural adhesive joints for transport applications

Sintesi di materiali avanzati mediante radiazioni ionizzanti

Gamma-radiation ageing of a low density polyethylene. Effects of irradiation temperature and dose rate

Abstract Ageing due to gamma radiation of a low density polyethylene at various dose rates and temperatures is studied; the effect of thermal treatment only is also considered. The modifications induced in the molecular and crystallinity behaviour of the polymer are investigated by means of gel extraction, measurements of intrinsic viscosity and thermal analysis. Results indicate the occurrence of both crosslinking and oxidative degradation; the extent of the latter increases on decreasing the irradiation dose rate and on increasing the irradiation temperature. Some exceptions are found because of the increase in the mobility of free radicals at high temperature. These effects modify also t…

Carbon Fiber Composites Cured by γ-Radiation-Induced Polymerization of an Epoxy Resin Matrix

The use of ionizing radiation in order to initiate polymerization of suitable monomers has found increased interest in the last two decades due to its several advantages. In this work, carbon fiber composites through gamma radiation polymerization of epoxy matrices have been produced for aerospace and advanced automotive applications. Composite samples were produced by irradiation at room temperature using different radiation doses and, as reference, thermal curing of the same epoxy resin formulations was also carried out. Furthermore, some irradiated samples were subjected to postirradiation thermal curing to complete the polymerization reactions. The properties of the cured materials were…

Ionizing radiation induced curing of epoxy resin for advanced composites matrices

Abstract The radiation curing of an epoxy monomer in the presence of an iodonium salt, as photo initiator, is studied. Systems with different concentrations of photo initiators have been polymerized via both gamma rays and e-beam, at various dose rates. The aim of this work is to investigate how the photo initiator concentration and the irradiation dose rate affect the temperature of the systems during curing and how the different thermal histories influence the dynamic mechanical thermal properties of the obtained materials.

Novel epoxy formulations for high energy radiation curable composites

Abstract It has been widely recognised that high energy radiation can be effectively applied to the cure of epoxy resins in applications as composite matrices or structural adhesives with improvements in product quality and/or reduction in production costs. In the presence of suitable initiators, polymerisation of epoxies occurs via cationic mechanism, thus restricting the choice of the resin system components to species which do not contain electron donor groups. The present investigation is aimed to identify suitable co-monomers to be formulated with an epoxy resin, resulting in different cure reaction kinetics and application properties of the cured resin. In particular, four different a…

Novel Gamma-crosslinked Hydrogels for Intelligent Release of Actives

Synthetic and natural polymer nanoparticles as bio-imaging and therapeutic agent vectors

Study of the Curing Process of DGEBA Epoxy Resin Through Structural Investigation

In this work, a multi-scale approach with different analytical methods is applied to study the curing process and the structural properties of a diglycidyl ether of bisphenol A (DGEBA) epoxy resin. This monomer, thermally cured using 4,4′-diaminodiphenilsulfone (DDS) as hardener, is analyzed after 10, 45, 90, and 120 min of reaction time at 180 °C to obtain information on samples with different cross-linking densities. Samples are also characterized after extraction in acetone in order to obtain structural information on the insoluble parts. For this purpose, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), solid-state nuclear magnetic resonance (ss-NMR),…

Radiation engineering of functional biomaterials: from smart hydrogels to theragnostic nanodevices

A comprehensive experimental study of the rheological behaviour of HDPE.

Extensional properties of four high density polyethylenes with different molecular weights and molecular weight distributions are presented. The samples have already been well characterized in shear and non-isothermal extensional flow. The data were collected at 180 °C for elongational rates between 3 · 10−1 and 10−4s−1. Some qualitative and quantitative generalizations of the results are given.

Durability behaviour of aluminium alloy joints bonded with epoxy adhesives

High-energy radiation process, a "facile" and "versatile" approach to obtain PVP-graft- AA nanogels

Poly(N-vinylpyrrolidone)-grafted-acrylic acid biocompatible nanogels (NGs) were prepared using an exiting industrial-type electron accelerator and setups, starting from semi-dilute aqueous solutions of a commercial PVP and the acrylic acid monomer. As a result, NGs with tunable size and structure can be obtained quantitatively. Sterility was also imparted at the integrated dose absorbed. The chemical structure of the NGs produced was confirmed through Fourier Transformer Infrared Spectroscopy (FT-IR). The molecular and physico-chemical properties of NGs, such as the hydrodynamic dimensions and surface charge densities, for various polymer and monomer concentrations in the irradiated solutio…

Electrical properties of γ-crosslinked hydrogels incorporating organic conducting polymers

Abstract Hydrogel composites containing nanoparticles of the protonated emeraldine form of polyaniline (PANI-PE) have been synthesised by γ-irradiation, using either polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA) as steric stabilisers. Swelling behaviour of both hydrogels is reported, together with an electrical characterisation of composites, before and after gel network formation, performed by cyclic voltammetry and impedance spectroscopy. Similarities and differences between the two composite systems are discussed.

Sintesi e caratterizzazione di idrogeli biocompatibili stimolo-sensibili

The influence of the rubber carboxyl functionality on the processability and properties of solid rubber modified epoxy mixtures

A high molecular weight, carboxyl functionalised solid rubber was added to an epoxy resin-aromatic amino system developed for autoclave curing of honeycomb core composite structures. The achievement of an optimal balance of viscous flow and viscoelasticity of the resin, by controlling the nature and extent of cross-linking of the functionalised rubber, was proposed as a route to void-free honeycomb skins. The aim of the present investigation is to understand how the concentration of carboxylic groups of the rubber, prereacted with one of the epoxy monomers, affects the matrix resin flow properties. The concentration of carboxyl groups was changed by reacting them with a monofunctional epoxy…

Toughened matrices for advanced carbon fibre composites obtained through e-beam curing of two different epoxy-thermoplastic blends

Cure behaviour of epoxy resin matrices for carbon fibre composites

The cure behaviour of two resin formulations (with high and low curing agent content respectively) of an epoxy resin system, used as matrix for carbon fibre composites, was studied through calorimetric analysis. The aim of this work is to investigate the kinetics of this specific epoxy system in order to be able to choose a proper set of processing parameters which will give good composite material properties. The shape of the conversion curves gives evidence of the differences in the cure kinetics of the two systems. Furthermore, the values of the activation energies were determined both for formulation in the conversion range where vitrification occurs, following a phenomenological approa…

Ionizing radiation curing of epoxy based blends in order to produce high performance composites

Influence of morphology and chemical structure on the inverse response of polypropylene to gamma radiation under vacuum

Abstract In this work the influence of the chemical structure and of the morphology on the gamma-radiation effects on polypropylene based polymers is studied on the basis of a previously discussed kinetic model [1] . For this aim an isotactic polypropylene and a random ethylene–propylene copolymer were irradiated under vacuum at one dose rate and several absorbed doses after well defined solidification conditions. We show that the model is reliable varying both the chemical structure and the morphology of the polypropylene based polymer. An inversion of the response of the material to gamma radiation under vacuum is always observed, and the inversion conditions depend on the irradiation par…

CONTROLLED DELIVERY OF WATER-INSOLUBLE ACTIVE INGREDIENTS IN AIR FROM HYDROGEL MATRICES

Effect of hydrothermal ageing on the thermal and delamination fracture behaviour of CFRP composites

Abstract This work investigates the hydrothermal ageing behaviour of a carbon fibre reinforced laminate and its epoxy matrix in bulk conditions. A model DGEBA epoxy is employed, and water uptake and dynamic mechanical thermal (DMTA) analyses have been performed on both the composites and bulk resin. Fracture toughness of the bulk resin has been measured, evidencing a substantially unmodified critical stress intensity factor KIC, although the evidence of plasticisation effects given by DMTA. Interlaminar Mode I fracture toughness of the composite showed a variable trend towards slight decreases or slight increases, according to the prevailing toughening or embrittling mechanisms activated by…

Structure of e-beam sculptured poly(N-vinylpyrrolidone) networks across different length-scales, from macro to nano

Abstract Study of macromolecular structure and dynamics of networks formed by pulsed electron-beam irradiation of poly(N-vinyl pyrrolidone) (PVP) aqueous solutions, at relatively low energy per pulse and across different concentration regimes, provides the basis for the understanding of a new generation of functional nanostructures. Networks are the result of the follow–up reactions initiated by a continuous series of electron pulse-generated hydroxyl radicals, which may have a different fate at the variance of polymer concentration. Different spectroscopic techniques, FT-IR, 13 C { 1 H} CP-MAS NMR and Raman, applied to characterize the formed networks, describe a profound modification of t…

Solid State NMR Spectroscopy Investigation of the Molecular Structure of Epoxy Based Materials Cured in Different Conditions

In this work two epoxy resin model systems, whose monomers are typically used in structural composites, were thermally cured in different cure conditions in order to obtain different cross-linking densities. Their molecular structures were investigated through solid state NMR spectroscopy in order to correlate them to the cure process conditions used and the results were discussed in the light of the dynamical mechanical thermal analysis (DMTA) performed.

Influence of the e-beam irradiation and photo-oxidation aging on the structure and properties of LDPE-OMMT nanocomposite films

Abstract In this paper two systems, polyethylene (LDPE) and polyethylene/commercial organo-modified montmorillonite (LDPE/OMMT) nanocomposite, were subjected to e-beam irradiation at different doses and both the molecular modifications and mechanical properties have been investigated through solubility, FT-IR, calorimetric and tensile tests. Moreover, in some of the irradiated systems photo-oxidation aging was performed and its effects were studied. The results show an enhancement with irradiation of the positive effect of the nano-filler loading, related to the increase of the mechanical properties, due to the increase of the nano-filler polymer interaction. Nevertheless calorimetric and F…

Radiation Engineering of Multifunctional Nanogels

Nanogels combine the favourable properties of hydrogels with those of colloids. They can be soft and conformable, stimuli-responsive and highly permeable, and can expose a large surface with functional groups for conjugation to small and large molecules, and even macromolecules. They are among the very few systems that can be generated and used as aqueous dispersions. Nanogels are emerging materials for targeted drug delivery and bio-imaging, but they have also shown potential for water purification and in catalysis. The possibility of manufacturing nanogels with a simple process and at relatively low cost is a key criterion for their continued development and successful application. This p…

Therapeutic effects of benralizumab assessed in patients with severe eosinophilic asthma: Real-life evaluation correlated with allergic and non-allergic phenotype expression

Corrado Pelaia,1 Claudia Crimi,2 Alida Benfante,3 Maria Filomena Caiaffa,4 Cecilia Calabrese,5 Giovanna Elisiana Carpagnano,6 Domenico Ciotta Jnr,7 Maria D’Amato,8 Luigi Macchia,9 Santi Nolasco,2 Girolamo Pelaia,1 Simona Pellegrino,7 Nicola Scichilone,3 Giulia Scioscia,10 Giuseppe Spadaro,11 Giuseppe Valenti,12 Alessandro Vatrella,7 Nunzio Crimi2 1Department of Health Sciences, University “Magna Graecia” of Catanzaro, Catanzaro, Italy; 2Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy; 3Department of Biomedicine and Internal and Specialistic Medicine, University of Palermo, Palermo, Italy; 4Allergology and Clinical Immunol…

Radiation-Engineering of All Plastic Nanocomposite Films

In recent years, polymer nanocomposites have fascinated scientists, engineers and industrialists on the premise that the creation of new and more performing polymeric materials is possible by the combination of different building blocks with controlled dimensions at the nanoscale. Unfortunately, uniform dispersion of the hetero-phase domains within the plastic matrix or on its surface often fails due to the unfavorable thermodynamics, thus resulting in migration and irreversible aggregation phenomena. In-situ generation of a dispersed hetero-phase within the same polymer matrix or in its precursors increases the chances of achieving a better control of morphology by eliminating the often cr…

Epoxy resin based matrices for advanced composites cured by ionizing radiation. Study of the influence of process parameters on final properties

A commercial low density polyethylene was irradiated by gamma irradiation at room temperature with different integrated doses and dose rates. The modifications induced in the material were studied by means of solubility and swelling measurements and related to structural modifications by calorimetric measurements. Results indicate that crosslinking prevails with respect to degradation at high dose rates and that the ageing phenomena occur essentially in the amorphous phase. Ein kommerzielles Polyethylen niedriger Dichte wurde bei unterschiedlicher integrierter Dosis und unterschiedlicher Dosisleistung bei Zimmertemperatur mit Gammastrahlung behandelt. Die Veranderungen des Materials wurden …

Reactive blending of functionalized acrylic rubbers and epoxy resins

A high molecular weight acrylonitrile/butadiene/methacrylic acid (Nipol 1472) rubber is chosen to control processability and mechanical properties of a TGDDM (tetra glycidyl diphenyl methane) based epoxy resin formulation for aerospace composite applications. The physical blend of rubber and epoxy resin, achieved by dissolution of all the components in a common solvent, forms a heterogeneous system after solvent removal and presents coarse phase separation during cure that impairs any practical relevance of this material. A marked improvement of rubber-epoxy miscibility is achieved by reactive blending ('pre-reaction') the epoxy oligomer with the functional groups present in the rubber. The…

Sintesi di nanogeli per la veicolazione di insulina al cervello: una strategia per il trattamento della malattia di Alzheimer

I nanogeli sono nanoparticelle polimeriche reticolate idrofile. La struttura polimerica del nanogelo permette la coniugazione di molecole che possano esplicare azioni terapeutiche, diagnostiche e di indirizzamento attivo su siti bersaglio. Le caratteristiche di flessibilità e conformabilità del nanogelo, e delle sue maglie, ne favoriscono l’attraversamento delle barriere biologiche, l’interazione di eventuali ligandi esposti sulla superfice con i recettori target, un’azione protettiva nei confronti del principio attivo incorporato. L’irraggiamento con radiazioni ionizzanti di soluzioni acquose di polimeri è una metodologia sintetica interamente “water-based”, che garantisce rese elevate e c…

In-situ polymerization of polyaniline in radiation functionalized polypropylene films

Abstract In-situ generation of a nanodispersed conductive polymer within a polypropylene matrix has been pursued in order to obtain flexible, conductive films. Radiation grafting of acrylic acid to polypropylene (PP) has been applied to insert carboxyl functionalities on PP. The radiation-grafted films have been further derivatized with a variety of diamines and used as substrates for in-situ chemical oxidative polymerization of polyaniline (PANI). PANI grows as a thin skin from the surface of the film as well as an interpenetrated network in its interiors. Evidence of chemical attachment of PANI to PP has been sought by performing FTIR and XPS analyses after extraction of the unbound polym…

Structural investigation of e-beam cured epoxy resins through solid state NMR

Abstract In this paper the network structure of e-beam cured DGEBF based epoxy resins is investigated. Two epoxy systems, having different reactivity and cured in different process conditions, were analyzed through solid state NMR spectroscopy. The analysis shows that the more reactive system has higher cross-linking density and higher uniformity of network distribution. Similar information were obtained, in a previous work, on the same systems through dynamic mechanical thermal analysis. It is worth noting that unlike DMTA tests, which interfere with the molecular structure of the analyzed material, due to the heating during the analysis itself, more reliable information, without any artef…

Nuovi materiali nanocompositi a base di idrogeli e polimeri conduttori per l’elettronica molecolare

Radiation processing: a versatile methodology to tune the structure of polymeric materials

Structural induced modifications in blends of polyamide with gamma irradiated low density polyethylene

Abstract Blends of gamma irradiated and unirradiated low density polyethylene and polyamide 6 were made in order to study possible modifications induced by this irradiation. Results indicate that blends with gamma irradiated polyethylene have structure and properties significantly different with respect to blends made with the unirradiated one. This difference has been ascribed to the formation of functionalized groups in the polyethylene chains, which interact with polyamide.

Photonic crystal hydrogel films responsive to ethanol vapors

New biodegradable hydrogels based on an acryloylated polyaspartamide cross-linked by gamma irradiation

Alpha, beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA), a synthetic biocompatible macromolecule, was functionalized with glycidyl methacrylate (GMA) in order to introduce in its side chains residues having double bonds and ester groups. The copolymer (PHG), obtained from PHEA and GMA, had a degree of derivatization of 29 mol%. PHG aqueous solutions are cross-linked by gamma radiation at 0 degrees C either in the presence or absence of N,N'-methylenebisacrylamide (BIS) giving rise to new hydrogel systems. In both cases gelation occurs at quite low doses (0.26 and 0.4 kGy, respectively). The obtained networks were characterized by FT-IR spectrophotometry which confirmed that the cross-linki…

Pulse radiolysis and theoretical investigation on the initial mechanism of E-Beam polymerization of epoxy resins. The results obtained on (phenoxymethyl)oxirane

Influence of the irradiation parameters on the molecular modifications of an isotactic polypropylene gamma-irradiated under vacuum

Isotactic polypropylene was irradiated under vacuum in a complete set of experimental conditions. The influence of the irradiation parameters, total absorbed dose, D, and dose rate, I, was analysed in order to verify the theoretical predictions of a simple kinetic model, already presented (Sarcinelli L, Valenza A, Spadaro G. Polymer 1997;38:2307), based on the rates of the main reactions occurring during irradiation, i.e. β-scission, addition to double bonds and termination. The concentration of free radicals and double bonds formed during irradiation is detected together with a comparison to their dependence on the irradiation parameters. A quantitative determination of the “inversion curv…

Pulse radiolysis and theoretical investigation on the initial mechanism of the e-beam polymerization of epoxy resins. The results obtained on (phenoxymethyl)oxirane

Abstract The radical cation of (phenoxymethyl)oxirane ( PGE ⋅ + ) is generated by pulse radiolysis in dichloromethane solution and by direct action of radiation on the title compound. In the pure system its UV–vis spectrum is characterized by two bands at 340 and 430 nm, such that the electronic structure corresponds to a dipole bearing the positive charge on the phenoxy side. At the same time, the phenoxy-oxirane bridge is weakened. Then, the radical cation fragments into a phenoxonium ion and an oxyranylmethyl radical ( k PGE - fragm = 1.16 × 10 7 s - 1 ) . The latter immediately rearranges to an allyloxyl radical by ring opening. It is then conceived that the action of onium salts, as ra…

PROPERTIES OF IONIZING RADIATION CURED POLYMER MATRICES FOR CARBON FIBER COMPOSITES AFTER AGEING DUE TO MOISTURE ABSORPTION AND THERMAL TREATMENT

Mechanical properties-structure relationship in blends of polyamide 6 with γ-irradiated LDPE

Blends of γ-irradiated and unirradiated low density polyethylene with polyamide 6 were made in order to study possible modifications induced by this irradiation. Blends with γ-irradiated polyethylene show structure and properties significantly different with respect to blends made with the unirradiated polyethylene. In this paper data on mechanical properties (tensile and impact) of these blends are presented. Results are related to the different morphologies in the blends.

Radiation synthesis of polyaspartamide functionalised hydrogels for sustained release of fragrances

The aim of the present investigation is to assess the possibility of obtaining a biocompatible material device which is able to deliver oil-soluble fragrances in air over a length of time. Aqueous solutions of polyaspartamide functionalised with glycidyl methacrylate have been cross linked through gamma irradiation in the presence of a lipophilic model fragrance, emulsified prior to irradiation. Two emulsification conditions have been considered at two different concentrations of both fragrance and surfactant in water. Chemical hydrogels have been obtained in correspondence to two irradiation absorbed doses and have been characterised for their solubility properties and swelling ability in …

Studies of network structure and dynamics of e-beam crosslinked PVPs: From macro to nano

Much interest has been paid to develop a variety of radiation-crosslinked hydrated polymeric materials, which swell in water but do not dissolve, as biocompatible materials used for wound healing, drug delivery system, surface-coating material for medically used devices, etc. With the aim of establishing design rules to produce hydrogels of controlled size at the nanoscale and desired internal network structure using conventional electron accelerators and set-ups, here we attempt a description in terms of structural and dynamic properties of polymer networks generated through e-beam irradiation of aqueous solutions of the same model polymer, a commercial grade poly(N-vinyl-pyrrolidone), sub…

Gamma radiation induced maleation of polypropylene using supercritical CO 2 : preliminary results

Abstract The charging of maleic anhydride (MA) and dicumyl peroxide (DCP) into polypropylene matrices has been carried out by CO2 in supercritical conditions. The grafting of MA into polymer chains was done through gamma irradiation in CO2 atmosphere (0.1 MPa, 25°C). The grafting was successful and the amount of grafted anhydride was dependent on the amount of MA and DCP charged into the polypropylene matrix. The presence of grafted succinic anhydride was shown by FT-IR spectroscopy and its amount was determined through a calibration curve derived from standard samples. The effect of swelling due to supercritical CO2, maleic anhydride grafting and gamma irradiation on the molecular structur…

High energy radiation cure of resin systems for structural adhesives and composite applications

Abstract Radiation cure polymerisation of a commercial diglycidyl ether of bisphenol F epoxy resin has been achieved using a 60Co irradiation source, compounding the monomer with few percentage of an onium salt catalyst. The cure process has been monitored by a gamma-calorimetric technique and systems irradiated at doses corresponding to different positions in the gamma-calorimetric curve have been characterised via solubility tests and dynamic mechanical torsion analysis. Changes in both the measured gel fractions and tan δ values were associated with the progress of polymerisation and crosslinking reactions and these were dose dependent. Furthermore, systems irradiated at lower doses exhi…

Epoxy resin-thermoplastic blends as polymer matrices for carbon fiber composites

Properties and morphology of PMMA/ABN blends obtained via MMA in situ polymerisation through γ-rays

Abstract Methylmethacrylate polymerisation in the presence of 4 wt% butadiene-acrylonitrile rubber was carried out at fixed dose-rate and temperature. The effect of irradiation was investigated with respect to the mechanical and dynamic-mechanical properties in the solid state. A general increase of the “compatibilisation” on irradiation is obtained. In fact both rubber and polymethylmethacrylate glass transition temperatures, determined through dynamic-mechanical analysis, reveal the presence of strong interactions between the components. Furthermore an improvement of the mechanical tensile properties of the blends is observed when irradiation is continued after polymerisation, at least un…

Economic impact of mepolizumab in uncontrolled severe eosinophilic asthma, in real life

Abstract Background and aims Severe asthma is burdened by frequent exacerbations and use of oral corticosteroids (OCS) which worsen patients’ health and increase healthcare spending. Aim of this study was to assess the clinical and economic effect of adding mepolizumab (MEP) for the treatment of these patients. Methods Patients >18 years old, referred to 8 asthma clinics, starting MEP between May 2017 and December 2018, were enrolled and followed-up for 12 months. Information in the 12 months before mepolizumab were collected retrospectively. The evaluation parameters included: OCS use, number of exacerbations/hospitalizations, concomitant therapies, comorbidity, and annual number of workin…

Internal properties of gamma-irradiated polymeric hydrogels studied by means of fluorescent probes