Synthesis and Viscoelastic Properties of Smart Hydrogel

Here we report the synthesis and viscoelastic properties of smart hydrogels based on N-isopropylacrylamide, cationic (3-acrylamidopropyl)trimethylammonium chloride and nanoclay. Hydrogels were prepared by aqueous free radical polymerization. The effect of some salts, N,N '-methylenebisacrylamide, (3-acrylamidopropyl)trimethylammonium chloride and nanoclay content on the viscoelastic properties was studied. Also volume phase transition temperature and thermal behavior of the prepared hydrogels were investigated. Synthetic nanoclay and anionic groups of the bind to the cationic co-monomer units and significantly affected the viscoelasticity and thermal properties of the hydrogels. DSC measurements showed that the volume phase transition temperature of hydrogels depended on nanoclay content. By introducing of co-monomer, 250 mM solution of NaCl 15 mM bis(trifluoromethane)sulfonimide lithium salt (LiNTF2) and laponite nanoclay, a 10, 4, and 3.8 fold increase in elastic module was obtained, respectively, compared to that of the homopolymer PNIPAM hydrogel. With a temperature change from 20 to 45°C for the homopolymer PNIPAM hydrogel in 15 mM LiNTF2, the elastic module grew 5 times larger.