Photoresponsive Multilayer Films of Chitosan and an Azopolymer

The main goal of this work was the development of photoactive multilayer films. Taking into account that chitosan is a biodegradable, biocompatible, nontoxic, and antibacterial biopolymer, the fabrication of chitosan-based multilayer films can be an interesting pathway to obtain biopolymer-based films in which properties can be combined with a light-responsive material, such as an azobenzene-containing polymer. In particular, the layer-by-layer technique was used for the fabrication of the optically active films consisting of alternating layers of chitosan and an azopolymer. The influence of the pH and the number of bilayers on the structure and properties of the films was investigated by different experimental techniques and it was found that the roughness and elastic modulus of the multilayer films increased with the decrease in chitosan solution pH. Besides, induced birefringence measurements revealed that a higher level of photoorientation was attained with the decrease in pH and the increase in bilayer number of the developed films.