Water/acetone permeability of porous hollow-fiber membrane containing diethylamino groups on the grafted polymer branches.

Dietylamino (DEA) groups were introduced into a porous hollow-fiber membrane having a nominal pore size of 0.34 micrometer and porosity of 71% via two reactions: graft polymerization glycidyl methacrylate (GMA) and subsequent functionalization. The graft chains were formed both on the pore surface and in the amorphous domain of the polymer matrix, and were distributed uniformly throughout the membrane. Water and acetone were forced to permeate across the porous membrane the DEA group density of which ranged up to 6.7 mol per kg of the starting hollow fiber membrane with a 100% constant degree of GMA grafting. The density of the DEA groups on the graft chains induced conformational changes which altered the permeability of the membrane. The pure water flux curve exhibited a sharp decrease at a conversion ratio of the epoxide group to the DEA group between 40 and 60%. The acetone flux curve had a maximum value near the 20% conversion point. The DEA-group-containing membrane, with a conversion below 20%, showed a higher swelling in acetone than in water. This is due to the swelling of the graft chains invading the amorphous domains.