Chitosan membrane with patterned surface obtained through solution drying

Chitosan membranes with self-organized lines on surface were obtained. SEM and laser diffraction techniques showed that structures with peak-valley periods of about 5 ± 2 μm were observed in both porous and dense chitosan membranes. These unique patterns may be of special interest for applications where micro-mechanical interactions are important such as for biomaterials. The procedure used to produce these membranes consisted of casting, drying of a 2.5% chitosan solution, followed by coagulation using 1.0 M NaOH solution. The analyses indicate that the drying step is the most important to shape the organized surface pattern. This is in agreement with literature that cites that when layers of polymer solutions undergo solvent evaporation and/or heating from below, the interface can become unstable, generating patterns, depending on the surface tension differences and density effects, fluid motion can be generated and amplified, through the known Marangoni effect.