Preparation and properties of chitosan/poly vinyl alcohol asymmetric membranes by supercritical CO2
Wound dressings with asymmetric porous membranes play an important role in the treatment of skin injuries.At present,most asymmetric membranes are prepared by dry/wet phase transformation,but most solvents and non-solvents used in this method are cytotoxic,and the prolonged drying process can lead to the collapse of the porous structure.In view of the above problems,an asymmetric membrane was prepared by supercritical CO2 phase conversion using polyvinyl alcohol and chitosan as raw materials.The effects of different mass fractions of casting liquid(6％,7％,8％,9％)on the morphology,structure and properties of the membrane were investigated.The results showed that all four membranes have obvious asymmetric structure,and the mechanical properties of the asymmetric films(tensile strength 6.07～14.3 MPa,tensile modulus 3.17～9.82 MPa)and water absorption(177.8％～254.0％)were within the desired range of ideal wound dressings.With the increase of the mass fraction of casting liquid,the density of the surface layer and the thickness of the dense layer increased correspondingly,the water absorption rate decreased,and the tensile strength increased.In addition,the asymmetric membrane produced by 8％casting liquid had micropores,mesoporous and macropores at the same time,which had a potential application prospect in the field of wound dressing.
asymmetric membranepolyvinyl alcoholchitosansupercritical CO2
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