Preparation And Properties Of Silicone Modified Chitosan Film

Chitosan is a kind of ideal natural macromolecule membrane materials due to their good filming and easy-transform. Chitosan membrane has been widely applied in various fields, especially in biomaterial because of their unique properties such as biocompatibility, biodegradability and antibacterial activity, good penetrability and adsorptivity, and certain mechanical strength. But the inherent brittleness and stiffness of chitosan membrane have limited many possible applications. Polydimethylsiloxane (PDMS) possess a serial of excellent properties such as low glass transition temperature, very good thermal and oxidative stability, low toxicity, good biocompatibility, etc. Therefore, PDMS is especially suitable for use as biomaterials. PDMS was thus incorporated into chitosan in this dissertation to modify their capability, which provides an important approach for modification of chitosan membrane.In this paper, epoxy-containing polydimethylsiloxanes (EP-PDMS) were prepared via hydrosilylation reaction by H-containing silicone oil and allyl glycidyl ether (AEP), with platinum-divinyltetramethyl-disiloxane complex [Pt (0) Karstedt catalyst] as catalyst. EP-PDMS was characterized by Fourier transform infrared spectroscopy (FT-IR). The intrinsic viscosity of EP-PDMS was determined by the Ubbelohde viscometer, and the molecular weights of EP-PDMSs were compared. Effects of react temperature, react time and mixture ratio on hydrosilylation reaction were investigated, the result shows that the optimal reaction time is 5-6 hours, reaction temperature is 90~110°C, and the mole ratio of AEP to Si-H is 1.2:1.The reaction of the epoxidized PDMS and chitosan was carried out in an acidic aqueous solution, then the modified chitosan membranes were obtained in a special mold. The chitosan membranes were characterized by FT-IR and X-Ray. Rresults showed that crystallinity of the modified chitosan membranes decreased with increasing silicone content in the membranes. The surface morphology of chitosan membranes were characterized by scanning electron microscope (SEM), the results showed that the surface of chitosan membrane was smooth and densified; micropores were found in the surface of modified chitosan membrane. Effect of casting condition on the preparation and properties of chitosan membrane were investigated. The optimal casting condition are as follows: material of mold is glass, the casting solution concentration is 2wt%, and drying temperature is 50℃.The effect of amount and molecular weights of EP-PDMS on mechanical properties of chitosan membrane were investigated. The results showed that the tensile strength and the tear strength of membranes decreased as the EP-PDMS content increased. After modified by silicone, the elongation at break of chitosan membrane increased obviously, and the elongation at break of chitosan membrane increased as the EP-PDMS molecular weights increased. Incorporation of EP-PDMS into chitosan rendered the membrane more flexible compared with unmodified ones.The effect of amount and molecular weights of EP-PDMS on swelling properties of chitosan membrane were studied. The results showed that the water swelling ratio first increasing then decreasing with the EP-PDMS content increasing; the water swelling ratio increasing with the EP-PDMS molecular weights increasing. In addition, wetting angle measurements indicated that incorporation of the silicone enhanced its hydrophobicity in comparison with unmodified ones.The thermal property of membranes was investigated by thermo-gravimetry (TG) analysis, which indicated that the increase of amount of EP-PDMS could improve the thermal stability of chitosan membranes.