Controlled deposition of structured polymer films: chemical and rheological factors in chitosan film formation

Abstract

The technique of spread-coating was utilized to create thin films of chitosan polymer. The effect of deposition rate on film thickness was characterized for solutions of deacetylated and butyl-modified chitosan. For the range of deposition rates analyzed, the relationship between film thickness and increasing deposition rate fell into three distinct regions: an initial inverse relationship, a second linearly increasing relationship, and a final region wherein the film thickness remained constant. Results suggest that film thickness was both controllable and reproducible and that hydrophobic modification of the polymer extends the range over which a linear relationship between film thickness and deposition rate is achieved. Viscometry and fluorescence spectroscopy were employed to characterize the micellar characteristics of solutions of both deacetylated and butyl-modified chitosan. Deacetylated chitosan solutions possessed more interconnected hydrophobic domains that had more intermolecular micellar characteristics, while butyl-modified chitosan solutions had more intramolecular micellar characteristics and less interconnected hydrophobic domains.