A facile method for the fabrication of covalently linked PAH/PSS layer-by-layer films†
We report a facile method for the fabrication of robust polyelectrolyte multilayers including strong polyanions. Covalently cross-linked PAH/PSS [PAH: poly(allylamine hydrochloride); PSS: poly(sodium-p-styrene sulfonate)] multilayered films are fabricated using a traditional layer-by-layer technique, followed by post-infiltration of a bifunctional photoactive molecule 4,4′-diazido-2,2′-stilbenedisulfonic acid disodium (DAS) and subsequent photochemical cross-linking. The stability of the cross-linked multilayers was enhanced significantly. Over 90% of the cross-linked multilayers were preserved in a basic solution or good solvent of the polyelectrolyte, forming a clear comparison with the un-crosslinked multilayers, which almost completely decomposed under the circumstances mentioned above.