The Preparation And Studies Of Structure And Property Of Chitosan-Based Porous Membranes

Biodegradable synthetic polymers have some advantages such as controllable capability no immunogenicity and excellent bioeompatibility and have been used widely in the biomedical field. Chitosan (CS), Poly (vinyl alcohol)(PVA) and Poly (lactic acid)(PLA) are three of the most investigated and utilized biodegradable polymers. CS has the functions of favorable biodegradable, antibacterial activity, and analgesic, restrain scab, and accelerate wounds healing. Due to the properties of excellent hydrophily and easy-into the films, PVA is commonly used in the polymer blends to improve other polymers’ property. The biodegradability and high degradation security of PLA in peoples’ body have been confirmed by scientists. This paper has prepared different blend membranes based on CS, combining the advantages of the different polymers, with greater potential application in the field of biological wound dressing.In this paper, the phase inversion, porogen and freeze-drying method were used respectively to prepare the pure chitosan films. It was found that the freeze-drying method possessed simpler pore-forming process and more uniform holes on the surface of films than the other two methods. Based on these results, this paper adopted the freeze-drying method. The blend membranes with the different contents of CS/PVA、CS/PLA and CS/PVA/PLA respectively were prepared. By configuration of chemistry and physics capability, the absorbability, water vapor permeability, porosity and the tensile strength of all proportion blend membranes were researched, and the microstructure and degradable property of the membranes were investigated by FTIR, DSC and SEM.The results showed that:the absorbability, water vapor permeability, porosity of the binary and ternary membranes were enhanced. These properties will increase when CS at the certain range of concentration increased. As to different proportions of CS/PVA blend membrane, its breaking strength had been improved with the addition of PVA, while the breaking elongation kept constant increasing. The breaking strength of CS/PLA blend membranes at different ratios increased at first and then decreased with the the content of CS decreasing and the elongation decreased. The comprehensive property of the porous membranes with the content of CS60%is optimal. CS/PVA/PLA membranes had enhanced breaking strength and the breaking elongation had been slightly damaged but improved with the increase of the proportion of PVA. Actually, we can improve the membranes’s brittleness and flexibility by adjusting the ratio of different polymers in the membranes. FTIR revealed that CS and PVA have better compatibility and there exists strong forces between the two components; CS/PLA and CS/PVA/PLA blend membranes gradually began to phase separation only when the content of chitosan reduced to50%. DSC curves indicated that the thermal decomposition temperature of the binary and ternary films mainly relies on the ratio of different components. In vitro degradation experiments, PVA can help to inhibit or delay the degradation rate of blend membranes when used for preparation of biological material. SEM images showed that three kinds of blend membranes have loose porous structure, the cross section was of the lamellar shape; and the membranes’ pore sizes, distribution and morphology of blends vary according to the proportion of the three polymers. We boldly predict that this sort of structure will have broad application prospects in the field of bio-medical, such as wound dressings, artificial skin, etc.