Interpenetrating polymer networks of poly(dimethyl siloxane–urethane) and poly(methyl methacrylate)

Simultaneous IPNs of poly(dimethyl siloxane-urethane) (PDMSU)/poly(methyl methacrylate) (PMMA) and related isomers have been prepared by using new oligomers of bis(β-hydroxyethoxymethyl)poly(dimethyl siloxane)s (PDMS diols) and new crosslinkers biuret triisocyanate (BTI) and tris(β-hydroxylethoxymethyl dimethylsiloxy) phenylsilane (Si-triol). Their phase morphology have been characterized by DSC and SEM. The SEM phase domain size is decreased by increasing crosslink density of the PDMSU network. A single phase IPN of PDMSU/PMMA can be made at an M_c = 1000 and 80 wt % of PDMSU. All of the pseudo- or semi-IPNs and blends of PDMSU and PMMA were phase separated with phase domain sizes ranging from 0.2 to several micrometers. The full IPNs of PDMSU/PMMA have better thermal resistance compared to the blends of linear PDMSU and linear PMMA. © 1993 John Wiley & Sons, Inc.     

Rheological properties of solutions and gels of combined systems hydrophobically modified polyacrylamides-new viscoelastic cationic surfactants

The rheological properties (viscosity and dynamic elasticity modulus) of solutions and gels of combined systems composed of hydrophobically modified polymers containing main-chain charged groups or lacking these groups and of newly synthesized viscoelastic cationic surfactants with different amounts of OH groups and long nonpolar saturated and trans monounsaturated radicals have been studied. It has been shown that the maximum viscosity of solutions of polymer-surfactant complexes corresponds to the very low concentration of the surfactant. Regions where homogeneous and heterogeneous combined solutions and gels exist are considered. An increase in the viscosity of the combined solutions with temperature is discovered and discussed. The synergistic effect of polymers and surfactants is demonstrated, and a more efficient role of surfactants in the case of uncharged polymers is revealed. The roles of the number of OH groups and the length of the nonpolar radical in a surfactant molecule and a difference in the properties of systems containing surfactants with saturated and unsaturated radicals are considered.     

Comparison of the association process in physical gels and in polymers with small amounts of stickers

The association processes in physical gels and physical networks with smal amount of stickers are compared on the basis of the generalization of literature data and our own results on the gels of gelatine, PVA and olygocarbodiimides as well as on the physical network formation in poly(dimethylcarbosiloxane) with side COOH groups. The measurement of the rheological properties is used as a main method of the association evaluation. The role of the rearrangement of the intra- to intermolecular bonds and of the thermodynamic quality of the solvent in the process of physical network formation is emphasized.     

Rheologische Eigenschaften der Gelatinel?sungen und -gele in verschiedenen L?sungsmitteln

Ohne Zusammenfassung     

Elektronen-mikroskopische Untersuchung der Strukturbildung in Polyvinylalkoholl?sungen und -gelen

Ohne Zusammenfassung     

Photocatalytic properties and structure of chitosan-based porphyrin-containing systems

The photocatalytic activity of the disodium salt of substituted hematoporphyrin in a model reaction of tryptophan oxidation in the presence of chitosan with different molecular masses and a block copolymer of ethylene and propylene oxides (Pluronic F-127) is studied. It is shown that, in the presence of the Pluronic, the catalytic activity of the chitosan-porphyrin system increases. The structure of chitosan-Pluronic systems, depending on the molecular mass of chitosan and the presence of porphyrin, is examined by AFM. A pleasible mechanism of the influence of the Pluronic on the photocatalytic activity of chitosan-por-phyrin systems is proposed.     

Swelling of interpenetrating polymer networks

We have studied the densities, kinetics, and equilibrium degree of swelling in a number of different solvents of poly(carbonate urethane)/poly(methyl methacrylate) and poly(carbonate urethane)/poly(vinyl pyridine) interpenetrating polymer networks (IPN's). The kinetics of solvent uptake are often anomalous. The equilibrium extent of swelling reflects, among other factors, the number of phases present. © 1993 John Wiley & Sons, Inc.