In order to synthesize a wide spectrum of hydrogels for drug delivery and environmental management technologies, starch was graft copolymerized with three acrylamides, viz: acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-isopropyl acrylamide. The synthesis was carried out at two different temperatures, including the gelatinization temperature of starch (70 °C). A redox system, comprising of ammonium persulfate and ferrous ammonium sulfate (APS: FAS = 2.185 mM: 0.255 mM) was used to initiate the polymerization reactions. Using the same reaction conditions that were used to obtain graft copolymers, crosslinked networks of all three acrylamides and starch were also synthesized in the presence of various concentrations of N, N-methylene bisacrylamide as crosslinker, also at two different temperatures. The hydrogels were characterized by FT-IR and thermal studies to ascertain some of their structural aspects, and also to obtain evidence of network formation. Water uptake by hydrogels was studied as a function of time, temperature and pH. Some of the hydrogels were very good absorber of water and it was observed that the synthetic conditions affected their structure; hence their water uptake was also affected. The hydrogels were environment-sensitive and they showed significant volume transitions when small changes were made in their environment.
Phase Separation and Network Formation in Poly(vinyl methyl ether)/Water Solutions