Study On Surface Hydrophobic Modification And Improved Preparation Method Of Chitosan Rod

In-situ precipitation method has been developed to prepare chitosan rod (CR). But, high water penetrating rate and large amount of water absorption of CR block its practical application as internal fixation of bone fracture, the preparation mechanism of CR is not very clear as well. In this thesis, surface acetylating and bio-ester coating were tried for surface hydroprobization of CR, and an improved preparation method was studied for clarifying in-situ precipitation mechanism further.1. The facts influencing the mechanical properties attenuation of CR in wet situation were studied. Acetic anhydride catalyzed by sulfuric acid was used to CR surface acetylation, the acetylation processing was optimized, and the final waterproof effect was characterized by FTIR, contact angle and water absorption rate also. Surface acetylation can increase contact angle of CR effective but works a little in delaying water penetrating.2. For coating a waterproof layer on the CR surface, comparison and selection have been made among several biocompatible materials. One kind of bio-ester was applied as coat finally for a trial. The coating progressing was studied. As shown in the result of experiment on mechanical properties attenuation of CR in artificial body fluid, the bio-ester lay with compact structure and strong adhesive ability has very good waterproof effect combined with surface acetylation method. Its prospective use and improvement measures were also discussed.3. Illumined by annual ring of wood, in-situ precipitation method was improved by changing uninterrupted precipitation into intermittent and controllable process, which produced a kind of CR with layered structure similar to annual ring on their cross section. The improvement is help to clarify the preparation mechanism of CR.