Study of cryostructuring of polymer systems: 22. Composite poly(vinyl alcohol) cryogels filled with dispersed particles of various degrees of hydrophilicity/hydrophobicity

Abstract

Composite poly(vinyl alcohol) cryogels formed by the freezing–thawing of aqueous concentrated polymer solutions containing suspended filler were prepared and studied. The particles of unmodified silica gels were used as solid hydrophilic fillers and silica gels with grafted C2, C8, and C18 alkyl groups, as hydrophobic fillers. The granules of cross-linked dextran gel (Sephadex) swollen in water were used as soft hydrophilic fillers and lipophilic Sephadexes modified with propylene oxide groups, as soft hydrophobic fillers. It was shown that the microstructure and mechanical properties of such composites are affected by the presence of hydrophobic dispersed phase, namely, as the hydrophobicity of dispersed particles rises, the rigidity of composites increases with filler concentration at progressively lesser extent.