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. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010