Controllable disintegration of temperature-responsive self-assembled multilayer film based on polybetaine

A layer-by-layer (LbL) self-assembly technique was used to construct temperature-responsive multilayer films of polybetaine poly-3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate (PDMAPS) and poly(acrylic acid) (PAA). The assembly and disintegration behaviors of PDMAPS/PAA multilayer films were investigated by quartz crystal microbalance (QCM) and atomic force microscopy (AFM). The results indicated that the assembly behaviors of PDMAPS/PAA multilayer films could be well regulated by the pH and temperature of dipping solutions. The disintegration of PDMAPS/PAA multilayer films could be well controlled by varying the disintegration temperature (Td) and the pH of buffer solution. The critical disintegration temperature (Tcd) decreased with increasing pH of buffer solution used. The ionization of carboxylic acid groups (COOH) of PAA and the breakage of intra-chain associations of PDMAPS in multilayer films are two main reasons for the film disintegration. Based on the controllable disintegration of the PDMAPS/PAA multilayer, free-standing multilayer films were successfully prepared by LbL self-assembly of poly(4-vinylpyridiniomethanecarboxylate) (PVPMC) and PAA using PDMAPS/PAA as a sacrificial sublayer.