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) (PVBCl) 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 microporous base membrane. The remaining chloromethyl groups were reacted with an amine, such as trimethylamine, to form positively charged ammonium sites. This simple two‐step procedure gave dimensionally stable, anion‐exchange membranes in which the degree of crosslinking and the mass loading were determined by the concentration of PVBCl and crosslinker in the starting DMF solution. The incorporated polyelectrolyte gel was evenly distributed within the pores of the host membrane with no surface layers present. The membranes are fully characterized. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 807–820, 2001 Robust, polyelectrolyte‐filled, microporous membranes were prepared by the crosslinking of poly(vinylbenzyl chloride) with a diamine within the pores of a microporous host membrane. The unreacted chloromethyl groups were converted to positively charged ammonium sites by a reaction with trimethylamine in a second step. This simple two‐step procedure gave dimensionally stable, anion‐exchange membranes with well‐defined and controllable degrees of crosslinking, mass gain, and ion‐exchange capacities. The properties of the membranes could be tuned for various applications.