Plasma‐polymerized organosiloxane membranes prepared by simultaneous doping of I2 molecules and the effect on liquid permeability

Glow‐discharge plasma polymerization of hexamethylcyclotrisiloxane was carried out on the cellulose acetate substrate in the presence of iodine crystal and the effect of I2 doping on liquid permeability such as water, cyclohexane, alcohol homologues, and a water–alcohol mixture was investigated. It was found that I2‐doped poly(siloxane) (PHMS–I2) membrane exhibited larger water permeability than nondoped (PHMS) membrane with anomalous pressure dependence (fourth power with pressure gradient). The permeability of alcohol homologues of PHMS membrane increased with increasing the molecular size and the hydrophobicity, whereas that of PHMS–I2 membrane decreased significantly. The presence of a small amount of hemoglobin also increased the water permeability of both membranes. From the results of flow tests of various kinds of fluid it was assumed that these membranes permeate the liquid predominantly by solution‐diffusion mechanism.