STUDIES ON MICROSTRUCTURE OF RADIATION-SY NTHESIZED PAM, PNAA AND P(AM-NAA) COPOLYMER HYDROGELS BY SCANNING ELECTRON-MICROSCOPE

The polymer hydrogels polyacrylamdde (PAM), poly sodium acrylate(PNaA) and P(AM-NaA) in different AM/NaA monomer unit ratios with lower cros slinking densities were synthesized by Co-60-gamma ray radiation polym erization in aqueous solutions. The microstructure of these dry hydrog el samples in which water was extracted by acetone was observed by sca nning electron microscope. The results indicate that different ratios of AM/NaA in these homopolymer and copolymer hydrogels have much influ ence on their microstructure. It is attributed to the relative strengt h of two kinds of opposite forces-hydrogen bond attraction and electro static repulsion which exist in chain segments of polymers. However, t he relative strength depends on different ratios AM/NaA, and finally a ffects the ways of polymer chain packing, As a result, there are obvio us differences in microstructure between homopolymers and copolymers.