Mechanical properties of poly(N-isopropylacrylamide-Co-itaconic acid) hydrogels

It is well known that polymer, of N-isopropylacrylamide (NIPA) show lower critical solution temperature (LCST) behavior in water and its gels have a volume phase transitional at about 34 degreesC in water. In this study, we reported the polimerization of NIPA in the presence of N,N'-methylenebisacrylamide (BIS). Poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-co-itaconic acid) hydrogels were obtained by swelling the resultant solid xerogels to equilibrium in water. The effects of monomer composition and concentration of added cross-linking agent oil the swelling behavior and mechanical properties of these hydrogels at 22 and 37 degreesC were investigated, the latter involving measurements uf shear in a DMTA system. The storage moduli at 22 degreesC lay within the range 9.08-5.08 KPa. At a fixed BIS concentration, an increase from 22 to 37 degreesC resulted in an increase in the shear moduli and the effective cro, stinking density (v(c)) and a decrease in the interaction parameter hydrogel/water, chi.