Electron-Beam-Induced Grafting of Chitosan onto HDPE/ATZ Composites for Biomedical Applications.

The surface functionalisation of high-density polyethylene (HDPE) and HDPE/alumina-toughened zirconia (ATZ) surfaces with chitosan via electron-beam (EB) irradiation technique was exploited for preparing materials suitable for biomedical purposes. ATR-FTIR analysis and wettability measurements were employed for monitoring the surface changes after both irradiation and chitosan grafting reaction. Interestingly, the presence of ATZ loadings beyond 2 wt% influenced both the EB irradiation process and the chitosan functionalisation reaction, decreasing the oxidation of the surface and the chitosan grafting.

Polymerization Reactions and Modifications of Polymers by Ionizing Radiation.

Ionizing radiation has become the most effective way to modify natural and synthetic polymers through crosslinking, degradation, and graft polymerization. This review will include an in-depth analysis of radiation chemistry mechanisms and the kinetics of the radiation-induced C-centered free radical, anion, and cation polymerization, and grafting. It also presents sections on radiation modifications of synthetic and natural polymers.

Degradation of pullulan irradiated in hydro-methanolic blends: Influence of cinnamyl alcohol at low absorbed dose of radiation.

This study reports on the effects of electron beam radiation on pullulan in both the dry state and hydro-methanolic blends containing cinnamyl alcohol (CA). The radiation chemical yields of scission (G(S)) and crosslinking (G(X)) were determined using Saito's formalism applied to the evolution of molecular weight (MW) with increasing absorbed dose of radiation. To satisfy the requirements of the statistical treatment, commercially available pullulan was fractionated to obtain a monomodal MW distribution with a dispersity close to 2.

Evidence of chitosan-mediated reduction of Au(III) to Au(0) nanoparticles under electron beam by using OH˙ and e⁻(aq) scavengers.

Selective scavengers of e(-)(aq) and OH˙ radicals were used to investigate the radiolytic synthesis of gold nanoparticles from Au(III) solutions in the presence of chitosan. This reaction does not exclusively follow the direct reduction by solvated electrons. Irradiation generates short-lived and long-lived reductive species derived from chitosan that efficiently convert Au(III) into Au(0) which aggregates to form clusters.

Electron beam irradiation of maltodextrin and cinnamyl alcohol mixtures: influence of glycerol on cross-linking.

The influence of glycerol on the electron beam-induced changes in maltodextrins-cinnamyl alcohol (CA) blends is examined with respect to its influence on the degree of chain scission, grafting, and cross-linking. The study is relevant to radiation-induced polysaccharide modification, specifically in the perspective of using blended starch as a thermoplastic material, where glycerol is commonly used as a plasticizer. In the absence of CA, glycerol protects maltodextrin from chromophore formation onto the main chain, but also induces more chain scission.

Reactivity of vinyl ethers and vinyl ribosides in UV-initiated free radical copolymerization with acceptor monomers.

The reactivity of various vinyl ethers and vinyloxy derivatives of ribose in the presence of diethyl fumarate or diethyl maleate was investigated for evaluating the potential of donor-acceptor-type copolymerization applied to unsaturated monomers derived from renewable feedstock. The photochemically induced polymerization of model monomer blends in the bulk state was monitored by infrared spectroscopy. The method allowed us to examine the influence of monomer pair structure on the kinetic profiles.

Diffusion behavior of isobornyl acrylate into photopolymerized urethane acrylate films: influence of surface oxidation during curing.

The diffusion of liquid isobornyl acrylate (iBoA) into photopolymerized films of urethane acrylate was shown to be strongly dependent on curing conditions. Fourier transform infrared (FTIR) monitoring of iBoA sorption into films photopolymerized in oxygen-free conditions reveals that diffusion proceeds according to Fick's laws. The diffusion coefficient and the total amount of absorbed monomer are dependent on the degree of cure of the polymer network.

Compared reactivity of allyl ribosides in UV-initiated free radical copolymerization with acceptor monomers.

The free radical copolymerization of allyl ribosides with diethyl fumarate and maleate was investigated for evaluating the potential of donor-acceptor type copolymerization applied to unsaturated monomers derived from renewable feedstock. The photochemically induced polymerization of model monomer blends was conducted in solution as well as in liquid films of bulk reactants. Infrared spectroscopy was used to monitor the consumption of the allylic donor monomer and of the butenedicarboxylate acceptor monomers.

Phase diagrams of monomer and uv-cured difunctional-acrylate-nematic-liquid-crystal systems.

This paper deals with the thermal properties of systems made of the difunctional monomer 1,6-hexanedioldiacrylate (HDDA) and the low-molecular-weight liquid crystal E7. Experimental phase diagrams of uv-cured and uncured solutions of HDDA/E7 systems are established with a polarized optical microscope and a differential scanning calorimeter and the data analyzed within a theoretical formalism that combines the Flory-Huggins model of isotropic mixing and the Maier-Saupe model of nematic order. Ultraviolet-curing samples with a difunctional monomer such as HDDA leads to a crosslinked polymer network and consequently an elastic contribution to the free energy is introduced according to the Flory-Rehner theory of rubber elasticity.