Formation of pore-filled ion-exchange membranes with in situ crosslinking:Poly(vinylbenzyl ammonium salt)-filled membranes

Robust, polyelectrolyte-filled, microporous membranes were prepared by the introduction and crosslinking of a preformed polymer within the pores of a poly(propylene) host membrane. Specifically, poly(vinylbenzyl chloride) (PV BCl) was reacted with piperazine or 1,4-diaminobicyclo[2.2.2]octane in an N ,N-dimethylformamide (DMF) solution contained in the pores of the microporo us base membrane. The remaining chloromethyl groups were reacted with an am ine, such as trimethylamine, to form positively charged ammonium sites. Thi s simple two-step procedure gave dimensionally stable, anion-exchange membr anes in which the degree of crosslinking and the mass loading were determin ed by the concentration of PVBCl and crosslinker in the starting DMF soluti on. The incorporated polyelectrolyte gel was evenly distributed within the pores of the host membrane with no surface layers present. The membranes ar e fully characterized. (C) 2001 John Wiley & Sons, Inc.