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ABSTRACT:Thermosensitive organic-inorganic (O-I) hydrogels have been synthesized by modification of poly-(N-isopropylacrylamide) (PNIPA) gels with silica from tetramethoxysilane (TMOS) or with [3-(methacryloyloxy)propyl]trimethoxysilane (MPTMOS). Inorganic silica and silsesquioxane domains were formed in situ by sol-gel process within the organic matrix. Two methods of PNIPA-based gel synthesis have been employed-polymerization under homogeneous and heterogeneous conditions. The hybrid hydrogels swollen in water exhibited swelling transition around 32 C. Introduction of the inorganic phase into the PNIPA gels resulted in faster deswelling kinetics and better mechanical properties of the gels prepared under homogeneous conditions. Further acceleration of deswelling and swelling kinetics was achieved by applying heterogeneous conditions of synthesis above the lower critical solution temperature.

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Selected commercially available amines, including N-substituted morpholines, were evaluated as single catalysts and as catalyst mixtures for polyurethane foam preparation. The motivation was the search for economically and environmentally attractive replacements of "classical" catalysts, like diazabicyclooctane, dibutyltindilaurate, and N,N-bis(2-dimethylaminoethyl)methylamine. Especially interesting was replacing dibutyltindilaurate, and also the possibility of using reactive catalyst derivatives that would be incorporated into polyurethanes, thus reducing the content of volatile organic compounds in the polymer. The catalysts were tested on a , -polybutadienediol + toluenediisocyanate-based system. In some experiments, toluenediisocyanate was replaced by the more reactive and environmentally friendly 4,4 -Methylenebis(phenylisocyanate) and polybutadienediol by polypropyleneglycol.

Unmodified or chemically modified montmorillonite (MMT) dispersed in water was added into the reaction mixture forming hybrid organic-inorganic (O-I) nanocomposite coating. Two basic systems made from functionalised trialkoxysilane and oligomeric diamine v. functionalised dialkoxysilane and triamine were prepared and compared. End properties depend not only on the concentration and kind of MMT used but also on the inner constitution of the O-I matrix. Already 1 wt-% of unmodified MMT influences considerably surface and mechanical properties, but the effect of chemically modified MMT is not so pronounced. This can be due to worse dispersion (scattering) of chemically modified MMT within the O-I matrix compared with unmodified one: while unmodified MMT is partially intercalated, partially exfoliated in the product, substantial amount of original, unaffected MMT clusters was found there. Solid state nuclear magnetic resonance spectroscopy confirmed the interaction of MMT platelets with the O-I matrix.