Polytetrahydrofuran amphiphilic networks II. Swelling behavior of polyacrylamide-l-polytetrahydrofuran networks

Abstract

The swelling behavior of polyacrylamide-l-polytetrahydrofuran (PAm-l-PTHF) amphiphilic networks was studied in detail. Four solubility parameters δ [= 16.7, 23.3, 30.2 and 47.3 (MPa)^1/2] were obtained. The values of 16.7 and 47.3 (MPa)^1/2 correspond to the interaction of the PTHF and PAm segments with solvent, respectively, while the other two reflect the synergistic effect of the two phases during swelling. In acetone–water mixture no “volume phase transition” occurs, but the same synergistic effect renders a maximum swelling at certain mixture compositions. In aqueous solution the networks are sensitive to ionic strength when the ionic strength is low. A dynamic study reveals that the swelling of the networks in both water and cyclohexane is a non-Fickian diffusion process. The swelling behavior is entirely due to the microphase-separated and bicontinuous structure of the amphiphilic networks.