Synthesis of Pure CDA Polymer Films

CDA films were prepared by dissolving 1 g of the polymer (cellulose acetate 39.7 wt % acetyl content, ρ = 1.3 g/cm³, Aldrich) in 100 mL of a mixture 1:1 chloroform (high-performance liquid chromatography (HPLC) grade, Aldrich) and acetone solvent, respectively (p.a. Aldrich, 99.8%), inside Erlenmeyer flasks. The mixtures were maintained under stirring for 24 h. Then, the solutions were poured into individual glassware with a flat base (such as Petri dishes). The solvents were left to evaporate in a fume cupboard, and the films were considered dried, without solvent residues, upon reaching constant weight. They were kept in a desiccator until testing. The thickness of the CDA films was measured with a micrometer and was ca. 200 μm. The films were cut in 4 cm × 4 cm pieces and placed in glass supports.