A solventless substrate-independent approach for synthesizing structurally well-defined polymer salt networks onto solid surfaces is described. This entails pulsed plasma co-polymerization of acid and base containing precursors. In the case of acrylic acid and allylamine, one manifestation of the deposited ionic and covalent cross-linked layers is that they promote the formation of a closely packed gas impermeable structure. (c) 2005 Elsevier Ltd. All rights reserved.