Preparation And Interfacial Properties Of Calcium Carbonate Coated With Chitosan-Adipic Acid

The CaCO3coated with chitosan-adipic acid(CAC) was prepared through the interaction between2site amino group of chitosan and carboxyl group of adipic acid. The structure of CAC was characterized by fourier transform infrared spectroscopy(FTIR), thermo-gravimetric analysis(TGA), X-ray difrraction(XRD) and scanning electron microscopy(SEM); Moreover, The Zeta potential, specific surface area, particle size distribution and contact angle of CAC were studied. The stability of chitosan layer and the bonding strength between coating and substrate were studied. The antibacterial properties of CAC were researched. The results showed that:(1) The results of FTIR showed that chitosan, adipic acid and CaCO3were not a simple physical adsorption. Chitosan was coated onto the surface of CaCO3through the interaction between2site amino group of chitosan and carboxyl group of adipic acid(2) The TG analysis indicated that the thermal stability of chitosan increased when it was coated on the surface of CaCO3. Decomposition temperature of chitosan was30degree higher than the origin chitosan. (3) The results of XRD showed that crystal structure of CaCO3was not destroyed after being coated with chitosan and adpic acid. The results of SEM showed that when the concentration of chitosan was more then5%,the surface of CaCO3was coated completely.(4) The coating of chitosan can improve the interfacial properties of CAC. Compared to the unmodified CaCO3, Zeta potential of CAC increased from-27.58mv to+13.11mv, specific surface area increased from2.846m2/g to4.709m2/g, average particle size decreased from11.21μmto7.49μm, contact angle increased from0degree to87degree when concentration of chitosan was9%.(5) The chitosan layer was stable in water dispersion system, its stability did not decrease after strring and ultrasonication. The results of FTIR also indicated that the structure of CAC did not change. But the chitosan layer was destroyed by grinding for30min.(6) After being coated with chitosan. CAC had antibacterial activity against to S. aureus and E. coli. The antibacterial activity of CAC was decreased even lost when the coating was damaged.