Effects of elastic polyurethane network on swelling/deswelling behaviors of polyacrylamide hydrogels

Interpenetrating polymer network (IPN) hydrogels composed of polyacrylamide(PAM) and polyurethane (PU) were synthesized in order to improve the responsive rate of PAM hydrogels.The changes of mass and volume of PU/PAM IPN hydrogels were measured in the process of absorbing-water/air-drying.By comparing the swelling/deswelling behaviors between PU/PAM IPN and PAM hydrogels,the effects of elastic PU network on responsive rate of PAM hydrogels were investigated.In the absorbing-water process,the PU network hindered the further expansion of swollen network rather than increase the swelling rate of PAM hydrogel obviously;whereas,in the initial stage of air-drying process the elastic network of PU could accelerate the deswelling process on a large scale due to the elastic recovery of PU network extended.Owing to the rapid response to the change of water content,the PU/PAM IPN hydrogels have large potentialities to be utilized as sensor and actuator in smart material systems.