Stabilization of hydrogen-bonded poly(N-isopropylacrylamide) multilayers by a dual electrostatic/hydrogen bonding copolymer

Multilayer thin films were prepared based on hydrogen bonding between poly(N-isopropylacrylamide) (PNiPAAm), and poly(styrene sulfonate-co-maleic acid) (PSSMA). Since PSSMA is capable of associating with other polymers through both hydrogen bonding and electrostatic interactions, multilayer assemblies incorporating PSSMA, PNiPAAm, and intercalated poly(allylamine hydrochloride) (PAH) layers were also prepared. Intercalated PAH layers were included to improve the pH stability of the film by introducing electrostatic linkages into the assembly. Film construction was studied as a function of pH of the deposition solution and the number of inserted PAH layers. Film morphology varied significantly with incorporation of PAH into the film. It was also demonstrated that by intercalating several PAH layers within the PNiPAAm/PSSMA assembly, the pH stability of the films at pH 5.8 could be substantially improved.