SILICONE RUBBER-HYDROGEL COMPOSITES AS POLYMERIC BIOMATERIALS .6. TRANSPORT-PROPERTIES IN THE WATER-SWOLLEN STATE

Permeation of inorganic salts in water-swollen silicone rubber-hydroge l composites consisting of a silicone rubber matrix and lightly cross- linked particles of poly(2-hydroxyethyl methacrylate), poly(2-hydroxye thyl methacrylate-co-methacrylic acid), poly(methacrylic acid), polyac rylamide or poly(acrylamide-co-methacrylic acid) hydrogels was investi gated. The results, together with earlier data on permeation of non-io n ic low-molecular-weight substances through the composite materials, were evaluated in terms of the free-volume diffusion theory. It was fo und that the materials with water content exceeding a certain limit ar e highly permeable to the salts, and that, as regards permeation prope rties, they behave as homogeneous water-swollen hydrogels. The depende nce of electrical conductivity of the water-swollen composites on the hydrogel phase content was measured, and the results are discussed in relation to other transport properties and to the structure of the mat erials.