Poly (vinyl methyl ether) hydrogel formed by high energy irradiation

Poly(vinyl methyl ether) shows a lower critical solution temperature behavi or in water. The dimension of the polymer molecules depends on the temperat ure. A thermo-sensitive hydrogel was synthesized by irradiation of an aqueo us solution of poly(vinyl methyl ether) with electron beam and gamma -rays. At high polymer concentration a bulk gel was formed. The structure of the gel in the dry, swollen and shrunken state was investigated by field emissi on scanning electron microscopy (FESEM). It could be shown, that the gel sy nthesized by electron beam has a sponge-like structure consisting of caviti es (approximate to 1 mum) separated from each other by a polymer layer full of holes (approximate to 10 nm). The macroscopic gel is characterized by s everal techniques, e.g. determination of the M-c-value by NMR-relaxation me asurements.