Search results for "Polymer"

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

2014

A library of monoalkenylsilsesquioxanes as potential comonomers for synthesis of hybrid materials

2018

In this paper we demonstrate a facile and efficient synthesis of monoalkenylsubstituted POSS compounds, i.e., R7(Si8O12)-alkenyl and R7(Si8O12)(OSiMe2)-alkenyl with a functional alkenyl group of chain length (from vinyl to dec-9-enyl, with or without additional –OSiMe2– spacer between the silsesquioxane core and alkenyl moiety) and with five types of inert groups (Et, iBu, iOc, Cy, Ph) at the POSS core. These compounds constitute a library of monosubstituted POSS systems, including thorough spectroscopic and thermal characteristics. These findings could be especially useful for material chemists applying the compounds as modifiers or comonomers for copolymerization reaction, e.g., with olef…

Novel green bio-composite geopolymeric thermo-plasters for innovative building applications: upcycling spent coffee ground

2022

This study proposes the reuse of spent coffee ground and biomass fly ash in the development of green geopolymeric thermo-plastering for innovative building applications. The former waste is the major residue of the brewing process, that is usually used as fertilisers or disposed of in landfill with extreme harmfulness for the natural environment. The latter is an industrial waste generated during the Kraft paper-pulp process, that is usually landfilled. The mortar is produced with a combination of metakaolin (30 wt.%) and biomass fly ash (70 wt.%), and natural siliceous sand filled with spent coffee ground (up to 17.5 wt.%). The high amount of reused waste makes the material an optimum cand…

Modeling and experimental approaches for the characterization of phase equilibria in polymer solutions

2012

Calculation of ternary polymer solution phase diagram via compressible lattice fluid model extended to specific interactions

2012

Ternary polymer solutions are currently employed for the production of porous structures (e.g. membranes and scaffolds for tissue engineering) via liquid-liquid phase separation techniques. The relation between processing conditions and thermodynamic features of the considered polymeric system determines the morphology of the as-prepared membrane. Therefore, in order to achieve a better control on a porous structure, a deep characterization of the phase behavior of a polymer solution is needed. The experimental derivation of phase diagrams is highly cost and time consuming, thus usually the cloud point curves of the system are directly measured. In this work, the compressible lattice fluid …

Oxidation-responsive and "clickable" poly(ethylene glycol) via copolymerization of 2-(methylthio)ethyl glycidyl ether

2016

Poly(ethylene glycol) (PEG) is a widely used biocompatible polymer. We describe a novel epoxide monomer with methyl-thioether moiety, 2-(methylthio)ethyl glycidyl ether (MTEGE), which enables the synthesis of well-defined thioether-functional poly(ethylene glycol). Random and block mPEG-b-PMTEGE copolymers (Mw/Mn = 1.05-1.17) were obtained via anionic ring opening polymerization (AROP) with molecular weights ranging from 5 600 to 12 000 g·mol-1. The statistical copolymerization of MTEGE with ethylene oxide results in a random microstructure (rEO = 0.92 ± 0.02 and rMTEG E = 1.06 ± 0.02), which was confirmed by in situ 1H NMR kinetic studies. The random copolymers are thermorespon…

Development of polypeptide-based therapeutics for topical delivery

2019

Topical administration represents the main route to attain local therapeutic activity of bioactive agents in several organs, such as the skin or the heart by means of devices that enhance drug transport through the endothelium acting as a reservoir. The complex structure of the skin protects the human body against potentially harmful external agents; however, this protective mechanism inhibits the penetration of topically administering bioactive agents employed for the treatment of skin diseases. Unfortunately, many of the topical drugs currently used or under evaluation in clinical trials lack the appropriate physico-chemical characteristics required for delivery through the skin. However,…

New Insights into Segmental Packing, Chain Dynamics and Thermomechanical Performance of Aliphatic Polyurea Composites: Comparison between Silica Oxid…

2021

Polyurea (PU) is intrinsically reinforced by its microphase-separated morphology, giving its excellent mechanical properties. In this study, it is shown how a high-index PU formulation applies easy diffusion of hard segments into the soft phase of the PU matrix and tune its chain mobility. Moreover, the interaction of micro (>100 nm), nano (<100 nm) fillers with the microdomains and their thermomechanical properties are unraveled. Herein, nanosilica oxide (NS) and micro titanium (III) oxide (Ti2O3) are incorporated at low loadings into a solvent-free two-component aliphatic PU via insitu polymerization. While NS achieves an interfacial interaction with urea groups and forms a tight ha…

Calcium mediated polyelectrolyte adsorption on like-charged surfaces.

2011

International audience; Monte Carlo simulations within the primitive model of calcium-mediated adsorption of linear and comb polyelectrolytes onto like-charged surfaces are described, focusing on the effect of calcium and polyion concentrations as well as on the ion pairing between polymers and calcium ions. We use a combination of Monte Carlo simulations and experimental data from titration and calcium binding to quantify the ion pairing. The polymer adsorption is shown to occur as a result of surface overcharging by Ca2+ and ion pairing between charged monomers and Ca2+. In agreement with experimental observations, the simulations predict that the polymer adsorption isotherm goes through …

LEAVES OFNERIUM OLEANDERL. AS BIOACCUMULATORS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) IN THE AIR OF PALERMO (ITALY): EXTRACTION AND GC-MS ANALYSIS,…

2005

Polycyclic Aromatic Hydrocarbons (PAH) were determined in the leaves of Nerium oleander L. an evergreen plant that occurs widely in both urban and rural areas, to monitor the degree of pollution in the urban area of Palermo (Italy) compared to remote areas. Twenty sites (urban roadside, urban, urban park, suburban and rural) in and around Palermo city were investigated. The purpose of this research was to investigate concentration levels and distribution patterns and relate them to possible sources. Analysis of 19 PAH was performed by gas chromatography/mass spectrometry (GCMS) using selected ion monitoring (SIM). The total amount of PAH ranged from 10 to 166 μg/Kg d.w. Each source gives ri…