Multilayer films composed of a thermoresponsive cationic diblock copolymer and a photoresponsive dye

This article describes the temperature-triggered self-assembly of poly[(2-dimethylamino)ethylmethacrylate]-block-poly[di(ethyleneglycol) methyl ether methacrylate] (PDMAEMA59-b-PDEGMA318, PDD) unimers to aggregates in aqueous solution as a function of pH and temperature. Moreover, we examined the influence of the aggregate size of the thermoresponsive PDD diblock copolymer on the quantity and thickness of the multilayer films self-assembled layer-by-layer (LBL) with poly(styrenesulfonate) PSS on a substrate as a function of solution pH and temperature. The aggregation state of the PDD exhibited a significant influence on the deposition of the PDD/PSS bilayers, especially the first bilayer: The larger the aggregate size, the more loosely the aggregates were packed into the film with a higher surface roughness. The quantity and thickness of the multilayer films, however, grew linearly during the alternate sequential LBL-deposition of the PDD and PSS, irrespective of the aggregate size. Furthermore, loading a hydrophobic spiropyran dye into the multilayer films was realized to allow the multi-stimuli-responsive materials for separation and sensing applications.