Dendronized polymer as building block for layer-by-layer assembly: Polyelectrolyte multilayer films for incorporation and controlled release of water-insoluble dye

The multilayer films of the carboxylic acid terminated Fréchet-type dendronized polymer (denpol) and poly(diallyl-dimethylammonium chloride) (PDDA) were fabricated using the electrostatic layer-by-layer (LbL) assembly technique on planar substrates. The influence of pH and ionic strength of the polyelectrolyte dipping solutions on the fabrication of the PDDA/denpol multilayer films has been investigated in detail. AFM images showed that pH of the polyeletrolyte dipping solutions can obviously influence the surface morphology and roughness of the denpol layer in the multilayer films. We also use a preassembly method for incorporating water-insoluble molecule of pyrene into interior of denpol, and then fabricate the PDDA/pyrene-loaded denpol multilayer films. Moreover, we demonstrated that the loaded pyrenes can be released from the LbL films, which can be controlled by ionic strength of immersing solutions. Interestingly, the pyrene-released multilayer film can be used to reload pyrene when immersing the pyrene-released film into a saturated aqueous solution of pyrene.