Universality of elasticity on PAAM-NIPA copolymer gels

Abstract

Polyacrylamide (PAAm)-N-isopropylacrylamide (NIPA) copolymers were prepared via free radical crosslinking copolymerization with different molar of NIPA varying in the range between 0 and 2 M. The mechanical properties of swollen PAAm-NIPA copolymers were characterized by the compressive testing technique. It is understood that the compressive elastic modulus was found to increase by increasing NIPA contents, keeping temperature constant at 30 degrees C. The critical exponent of elasticity, y above the critical NIPA concentration is found to be as 0.74, which is consistent with the suggestions of percolation for superelastic percolation network (SEPN) and the critical theory for PAAm-NIPA copolymers.