Degradation Behavior of Polymer Gels Caused by Nonspecific Cleavages of Network Strands

Abstract

We report a systematical study of degradation behavior of hydrogels that suffer from the nonspecific cleavage on the network strands. The volume of the gel specimens increased with the degradation progress, and denoted the temperature dependence and the network strand length dependence. Our new model based on the pseudo-first-order cleavage kinetics of the chemical bonds on the network strands well agreed with the degradation behavior. The estimated apparent degradation rate constants of the network strands were linear function of their length, corresponding to the network strand length dependence on the macroscopic volume change of the gel specimens. The estimated degradation rate constants of the chemical bonds on the network stand, which were ether and amide bond, obeyed the transition state theory. The calculated activation enthalpy of each bond was in the range of the values in previous studies, indicating the validity of our modeling