Silicone rubber is one of the biomaterials used for preparation of medical implants. The properties of silicone rubber and methods of their evaluation are surveyed with respect to the medical applications. For some applications the hydrophobic character of silicone rubber is undesirable and possibilities of its hydrophilisation are presented in this review as well. Special attention is paid to the process of preparation of hydrophilic silicone rubber-hydrogel composite materials based on acrylic and methacrylic acids derivatives and to the properties of such materials.

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The shape memory of hydrophilic composite materials based on silicone rubber and slightly crosslinked polyacrylamide, which is a non‐ionic hydrogel, has been studied. Before the shape memory testing, it was necessary to determine the glass transition temperature (Tg) of the slightly crosslinked polyacrylamide as well as the mechanical properties of the composites at temperatures above Tg of a crosslinked polyacrylamide. Afterwards, the shape memory of the composite material was tested by performing a set of simple experiments based on deformation and heating of test pieces, their subsequent cooling and deformation force removing, and their repeated heating or water swelling, during which the residual elongation was measured and calculated. The composite material shaped in this way resumes its original shape if it is again heated above Tg of the crosslinked polyacrylamide or allowed to swell in distilled water. There exists a limiting concentration of hydrogel phase (approx. 30 phr), which is limited by good dispersion and good contact of hydrogel particles within the silicone matrix, under which the shape memory does not occur, and above which it exists.

Hydrophilic composite materials were prepared by combining powdery poly-(acrylamide) hydrogel with various technical rubbers (natural rubber, chlorobutyl rubber, EPDM rubber). The dependence of the quality of the dispersions of powdery hydrogel in rubbers on the method of dispersion was studied and properties (swelling capacity in water, mechanical characteristics) of the composites were measured. The natural rubberhydrogel composites showed the best swellability ( S O v01.-%).The mechanical properties of the composites are comparable to those of the unmodified rubbers, both in the dry and water-swollen state. ZUS AMMENFASSUNG:Es wurden hydrophile Kompositmaterialien auf der Basis von Polyacrylamidhydrogel und verschiedenen Elastomeren (Naturkautschuk, Chlorbutyl-Kautschuk, EPDM-Kautschuk) hergestellt. Die Abhangigkeit zwischen der Dispergierungsqualitat des Hydrogels in den Kompositmaterialien under dem Herstellungsverfahren wurde untersucht. AuBerdem wurden einige Eigenschaften (Quellung in Wasser, mechanische Eigenschaften usw.) bestimmt. Die NaturkautschukhIydrogel-Komposite zeigen die beste Quellbarkeit ( S O v01.-%). Die mechanischen Eigenschaften der Komposite sind sowohl im trockenen als auch im gequollenen Zustand mit denen der unmodifizierten Kautschuke vergleichbar.