FABRICATION OF NANOPOROUS CHITOSAN MEMBRANES

Naturally derived biopolymers have been widely used for biomedical applications such as drug carriers, wound dressings, and tissue engineering scaffolds. Chitosan is a typical polysaccharide of great interest due to its biocompatibility and film-formability. Chitosan membranes with controllable porous structures also have significant potential in membrane chromatography. Thus, the processing of membranes with porous nanoscale structures is of great importance, but it is also challenging and this has limited the application of these membranes to date. In this study, with the aid of a carefully selected surfactant, polyethyleneglycol stearate-40, chitosan membranes with a well controlled nanoscale structure were successfully prepared. Additional control over the membrane structure was obtained by exposing the suspension to high intensity, low frequency ultrasound. It was found that the concentration of chitosan/surfactant ratio and the ultrasound exposure conditions affect the structural features of the membranes. The stability of nanopores in the membrane was improved by intensive ultrasonication. Furthermore, the stability of the blended suspensions and the intermolecular interactions between chitosan and the surfactant were investigated using scanning electron microscope and Fourier transform infrared spectroscopy (FTIR) analysis, respectively. Hydrogen bonds and possible reaction sites for molecular interactions in the two polymers were also confirmed by FTIR analysis

Impact of Biodegradable Chitosan-Based Coating on Barrier Properties of Papers

Aroma and oxygen-barrier properties of chitosan-coated papers were measured in order to evaluate the potential of these materials as biodegradable materials for food packaging. Firstly, two chitosans (Chi244 and Chi-652) were studied according to their ultimate biodegradability. Chi-652 showed the best final biodegradation rate and was then used for subsequent tests in association with papers. Then, oxygen-barrier and aroma-barrier properties of papers, Chi-652 films and Chi-652-coated papers were investigated. The Chi-652 films exhibited oxygen-barrier at low relative humidity and aroma-barrier comparable to synthetic materials already used in the packaged food industry. Both papers exhibited poor barrier properties toward oxygen and aromas. Although chitosan-coated papers showed promising results in regard to the aroma-barrier performance of papers, it did not improve their oxygen-barrier properties, probably because of the impact of the coating process on the tri-dimensional structure of the papers