Water sorption, membrane potentials, and ion permeability of styrene‐grafted Bombyx mori silk fibroin membrane

Characterization of styrene‐grafted Bombyx mori silk fibroin membrance was investigated. It was revealed from the water sorption and 1 H nuclear magnetic resonance (NMR) measurements that the amounts of water adsorbed on the silk fibroin membranes decreased by the styrene grafting and the states of water adsorbed on the styrene‐grafted silk fibroin membranes were not homogeneous; the presence of two components of water adsorbed on the membranes at 60% relative humidity was observed. In addition, the fraction of the fast component decreased with increasing styrene grafting. The membrane potentials increased with increasing of the grafting. The KCl permeability of the membrane strongly depends on the degree of styrene grafting.