The exploration of the micro-mechanism of the electrophoretic deposition of chitosan

Electrodepositon techniques, which are adopted to build functional surfaces of biomaterials constituted of biological macromolecules and mineral membranes, are receiving a great deal of attention. In this paper, highly oriented pyrolytic graphite with an atomically smooth surface was employed as the cathode substrate in the electrophoretic deposition of chitosan(CS), eliminating the side effect of the traditional metallic cathode to the revealing of the deposition characteristics of CS itself. SEM, TEM, AFM and XRD were applied to characterize and analyze the deposited CS coating surface. The results showed that, owing to the electric field force, the crystalline peak of its (110) plane was promoted and the orientation arrangement of the CS micro-structure existed in three levels, including the parallel arrangement of nano-scaled CS molecular aggregates in thin layers, the parallel arrangement of CS long strips with a bridge-liked structure joined each other in micron-level composed of those aggregates, and the flower-liked CS in micron-level when the deposit was relatively thick. It has been the first time to explore the parallel arrangement of CS molecular aggregates in the initial stage of electrophoretic deposition and to analyze the growth mode and the surface features of the flower-liked structure.