Estíbaliz Hernáez

A study of the thermal degradation of several poly(monoalkylaryl itaconates)

Abstract Thermal degradation processes in poly(monobenzyl itaconate), poly(mono-2-phenylethyl itaconate) and poly(mono-3-phenyl-1-propyl itaconate), have been studied by DSC, TGA, EGA and FTIR. These analyses have indicated the absence of glass transitions in the three polymers and the occurrence of thermal degradative processes at temperatures of 120 δC. This thermal behaviour is confirmed by thermogravimetric analyses (TGA) which allows us to distinguish between at least three different degradative processes below 250 δC. Evolved gas analyses (EGA), employing an FTIR detector, and the infrared spectra of the residue allow us to speculate about the degradative reaction mechanisms. Three main degradation reactions have been proposed at temperatures below 250 °C, namely cyclic and linear anhydride formation, with loss of water and the corresponding alcohol, and decarboxylation reactions at higher temperatures.

Synthesis and Characterization of Polyacrylamides in Inverse-Emulsions with an Isoparaffinic Solvent

Inverse-emulsion polymerizations of aqueous solutions of acrylamide (AM) in an isoparaffinic solvent were carried out using Span 80 as emulsifier. The conversions at the end of inverse-emulsion polymerizations were investigated by HPLC methods. The conversion has been influenced by the initiator concentration, the monomer concentration and the reaction temperature. The molar masses were determined by viscosity measurements, size exclusion chromatography (SEC) and static light scattering. The influence of initiator concentration, monomer concentration and reaction temperature on the average molar mass of polyacrylamide (PAM) was studied

Active Release Coating of Multilayer Assembled Branched and Ionic β-Cyclodextrins onto Poly(ethylene terephthalate)

Branched ionic cyclodextrins multilayers were assembled onto the surface of previously aminolyzed poly(ethylene terephthalate) in order to construct local drug delivery tailored platforms with potential applicability as materials for indwelling medical devices. The construction of the multilayers took place by the alternate deposition of ionic cyclodextrin derivatives and was characterized by surface zeta-potential measurements, X-ray photoelectron spectroscopy and, after fluorescent labeling of anionic branched cyclodextrins, by UV-vis spectroscopy and confocal fluorescence spectroscopy. Transmission electron microscopy is used for the first time to show the deposited coating, and an average thickness of ∼270nm for 20 bilayered covering was measured. Contact angle measurements showed great differences in the films as the number of cyclodextrin layers was increased, and highly hydrophilic (19.7±1.5° for 10 bilayers) surfaces were obtained. The loading and release capacity of the antimicrobial triclosan, as hydrophobic model molecule, from PET coated surfaces was also studied.