Investigation of the Internal Chemical Composition of Chitosan-Based LbL Films by Depth-Profiling X-ray Photoelectron Spectroscopy (XPS) Analysis
Chitosan-based thin films were assembled using the layer-by-layer technique, and the axial composition was accessed using X-ray photoelectron spectroscopy with depth profiling. Chitosan (CHI) samples possessing different degrees of acetylation (DA̅) and molecular weight (Mv̅) produced via the ultrasound-assisted deacetylation reaction were used in this study along with two different polyanions, namely, sodium polystyrenesulfonate (PSS) and carboxymethylcellulose (CMC). When chitosan, a positively charged polymer in aqueous acid medium, was combined with a strong polyanion (PSS), the total positive charge of chitosan, directly related to its DA̅, was the key factor affecting the film formation. However, for CMC/CHI films, the pH of the medium and Mv̅ of chitosan strongly affected the film structure and composition. Consequently, the structure and the axial composition of chitosan-based films can be finely adjusted by choosing the polyanion and defining the chitosan to be used according to its DA and Mv̅ fo...
Thiago B. Taketa; Danilo M. dos Santos; Anderson Fiamingo; Juliana M. Vaz; Marisa M. Beppu; Sérgio P. Campana-Filho; Robert E. Cohen; Michael F. Rubner
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