[Show abstract][Hide abstract] ABSTRACT: Oxygen permeabilities of nanocomposite films consisting of poly(methyl methacrylate) (PMMA) and different amounts of spherical zinc oxide (ZnO) nanoparticles were determined to investigate the barrier effect of this material with respect to particle content. A method was applied which is based on quenching of an excited phosphorescent dye by oxygen. Possible effects of the nanoparticles on the response of the dye molecules were investigated and were ruled out.
Full-text · Article · Feb 2009 · Macromolecular Rapid Communications
[Show abstract][Hide abstract] ABSTRACT: Amphiphilic diblock codendrimers consisting of dendrons of hydroxyl-containing poly(methallyl dichloride) (PMDC) and long alkyl-containing poly(urethane amide) (PUA) were synthesized in different generations. These codendrimers were found to self-assemble into ribbonlike aggregates in organic solvent and further formed three-dimensional networks and behaved macroscopically as gels. The width of the self-assembled ribbons decreases with the generation of both dendritic blocks. Multiple intermolecular hydrogen bonds between amide and hydroxyl groups were found to be the main driving force to form these self-assembled gels.
[Show abstract][Hide abstract] ABSTRACT: Oxygen permeabilities of different polymers were determined by using two different methods based on quenching of an excited phosphorescent dye by oxygen. In the first method, the phosphorescent dye platinum octaethylporphyrin is directly dissolved in the polymer film of interest whereas in the second method a sensor film is used which is separated from the film of interest by a spacer. The polymers investigated are PMMA, PVC, PVAc, cellulose acetate, PEMA, and PS. The resulting oxygen permeability coefficients are compared with data reported in the literature. It was found that oxygen permeation strongly depends on the protocol of preparation and thermal history of the films.
No preview · Article · Oct 2007 · Macromolecular Chemistry and Physics