Polymer-filled nonwoven membranes were prepared by filling the open pores of nylon nonwovens with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). PAMPS was synthesized via radical polymerization and crosslinked to prevent its dissolution in water. PAMPS-filled nylon nonwoven membranes showed enhanced dimensional stability and mechanical properties when compared with PAMPS membranes without nonwovens. The conductivities of PAMPS-filled nylon nonwovens were slightly lower than those of PAMPS membranes. Compared with PAMPS membranes without nonwoven hosts, both linear and crosslinked PAMPS-filled nylon nonwoven membranes exhibited lower vapor permeabilities for water, methanol, acetone, and dimethyl methylphophonate (DMMP). In addition, crosslinked PAMPS-filled nonwoven membranes presented high permselectivity on DMMP over water, which is critical for chemical protection application. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2568-2575, 2011