Search results for "polymers"
showing 10 items of 3567 documents
Poly(N-vinylhalogenocarbazole). II. On the synthesis of some 1,3,6,8-tetrahalogenovinylcarbazoles
1976
This paper presents results of a research program in which several vinyl carbazole polymers containing chlorine and bromine atoms in their molecules were polymerized and characterized by IR spectroscopy and thermoanalysis. The compounds were synthesized by reacting 2-chloroethanol benzenesulfonate with the appropriate halogenocarbazoles (Clemo-Perkin method) obtaining in this way some halogen derivatives of 9-(2-chloroethyl)carbazole; these derivatives following dehydrochlorination produced relevant vinyl derivatives. Results are evaluated in terms of reaction mechanisms and molecular structures of polymers synthesized.
Effect of stiffness on the phase behavior of cubic lattice chains
2005
Gran canonica Monte Carlo (GCMC) simulazioni assistite da tecniche di riponderazione istogramma sono stati utilizzati per studiare l'effetto della flessibilità catena sul comportamento di soluzione fase di cubi catene reticolari corti con 4-32 segmenti. Ciò è stato fatto variando un parametro di rigidità gradualmente fino alla media calcolata end-to-end distanza avvicinato la lunghezza totale. Per entrambe le catene flessibili e rigide si è riscontrato che la temperatura critica, ottenuta tramite mista analisi dei campi di dimensioni finite, aumentata lunghezza della catena e la densità critica trasferisce a valori più bassi, in accordo con le osservazioni sperimentali. Il estrapolato lungh…
A multifuctional nanoplatform for drug targeted delivery based on radiation-engineered nanogels
2020
Abstract Under a rational design, combining biologically active molecules, ligands to specific cell receptors and fluorescent, radioactive or paramagnetic labels into a single nano-object can bridge the unique properties of the individual components and improve conventional sensing, imaging and therapeutic efficacies. The validation of these functional nano-objects requires careful testing both in terms of physico-chemical properties and biological behaviour in vitro and in vivo, prior to translation into the clinic. Ionising radiation of aqueous polymer solutions is a viable strategy to produce multifunctional nanogels from aqueous solutions of hydrophilic polymers. By proper selection of …
Hyaluronic Acid–Silica Nanohybrid Gels
2013
Excessive water sorption and low mechanical properties are a severe drawback in some biomedical applications of hyaluronic acid (HA). A way to improve these properties is here explored through the novel concept of nanohybrid hydrogels consisting of a HA matrix including different amounts of silica-derived species. This inorganic filler phase controls the mechanical and swelling properties of HA cross-linked matrices. Below a 2 wt % of silica in the systems, nanoparticle aggregates of tens of nanometers and silica oligomers are distributed more or less homogeneously throughout the organic matrix, without percolating. This morphology of the silica phase is accompanied by an increased swelling…
Rheological and Mechanical Behavior of LDPE/Calcium Carbonate Nanocomposites and Microcomposites
2012
The increase of the interest in polymer nanocomposites has been leading to continuous growing search toward nanofillers alternative to the widely known clay-based ones. One of these possible alternatives is represented by calcium carbonate nanoparticles, which have not been widely investigated in such context. In this article, a study on the rheological and morphological behavior of dif- ferent low density polyethylene-calcium carbonate nanocomposites, compared with a reference calcium carbonate microcomposite, is presented. Several different nanosized calcium carbonates at different amounts were used. The results from the rheological and me- chanical tests outlined that only minor changes …
The Understanding of the Metazoan Skeletal System, Based on the Initial Discoveries with Siliceous and Calcareous Sponges
2017
Initiated by studies on the mechanism of formation of the skeletons of the evolutionary oldest still extant multicellular animals, the sponges (phylum Porifera) have provided new insights into the mechanism of formation of the Ca-phosphate/hydroxyapatite skeleton of vertebrate bone. Studies on the formation of the biomineral skeleton of sponges revealed that both the formation of the inorganic siliceous skeletons (sponges of the class of Hexactinellida and Demospongiae) and of the calcareous skeletons (class of Calcarea) is mediated by enzymes (silicatein: polymerization of biosilica; and carbonic anhydrase: deposition of Ca-carbonate). Detailed studies of the initial mineralization steps i…
Composite Hydrogels of Alkyl Functionalized Gellan Gum Derivative and Hydroxyapatite/Tricalcium Phosphate Nanoparticles as Injectable Scaffolds for b…
2021
An alkyl functionalized gellan gum derivative was here used to produce hydrogels containing hydroxyapatite and tricalcium phosphate nanoparticles as injectable nanostructured scaffolds for bone regeneration. The amphiphilic nature of the polysaccharide derivative along with its thermotropic behavior and ionotropic crosslinking features made possible to produce injectable bone mimetic scaffolds that can be used to release viable cells and osteoinductive biomolecules. The influence of different nanoparticles concentration on the rheological and physicochemical properties of the injectable systems was studied. We found that the presence of inorganic nanoparticles reinforces the three-dimension…
Hybrid Magnetic Nanostructures For Cancer Diagnosis And Therapy.
2017
Cancer is the second disease in the world from the point of view of mortality. The conventional routes of treatment were found to be not sufficient and thus alternative ways are imposed. The use of hybrid, magnetic nanostructures is a promising way for simultaneous targeted diagnosis and treatment of various types of cancer. For this reason, the development of core@shell structures was found to be an efficient way to develop stable, biocompatible, non-toxic carriers with shell-dependent internalization capacity in cancer cells. So, the multicomponent approach can be the most suitable way to assure the multifunctionality of these nanostructures to achieve the desired/necessary properties. T…
Application of molecularly imprinted polymers in analytical chiral separations and analysis
2018
Over the last two decades the process of development and application of a new types of molecular imprinted polymer (MIP) sorbents in the field of analytical chemistry have been widely described in the literature. One of the new trends in analytical chemistry practice is the use of new types of MIP sorbents as specific sorption materials constituting the stationary phase in advanced separation techniques. The following review paper contains comprehensive information about the application of a specific and well defined MIP sorbents (with the data base in the paper about the reagents used in MIP preparation process) as stationary phases in separation techniques including high performance liqui…
Analysis of the mechanical performance of hybrid (SPR/bonded) single-lap joints between CFRP panels and aluminum blanks
2013
Abstract The increasing use of innovative materials in manufacturing of modern mechanical components has led to the development of reliable joints between innovative (composite materials etc.) and traditional materials (steel, aluminum etc.). In the last few years, hybrid joints, combining the advantages of the adhesive joints and traditional mechanical joints as bolted or riveted joints, have been shown an increasing industrial interest especially in automotive and aerospace sectors. In the present paper a systematic experimental study of hybrid lap joints was carried out with the aim to detect the optimal joint configuration. Tensile tests on hybrid joints made by combining adhesive bondi…