改性壳聚糖及其膜材料的制备与表征

Preparation and Characterization of N-Methylene Phosphonic Chitosan and Its Membrane Material

以壳聚糖(CS)、亚磷酸和多聚甲醛为原料,制备N-亚甲基磷酸化壳聚糖(NPCS)。利用红外光谱和核磁共振波谱表征其结构。CS和NPCS膜对Ca2+的络合性能表明,磷酸化改性的NPCS膜对Ca2+的络合能力大大提高,钙离子的行为与p H有关,络合量随p H值增加而增加,在p H为10时的络合过程符合一级动力学。X射线衍射分析表明磷酸化壳聚糖的结晶度下降,膦改性壳聚糖与Ca2+络合后结晶度提高。原子力显微镜和扫描电镜分析表明,NPCS膜表面较粗糙,有一些圆柱状突起,经钙化后NPCS膜的表面趋于平滑细腻,出现一定螺旋结构的树枝状网络突起,深度为275 nm,螺旋条纹间距约为200~400 nm,这种螺旋状的枝杈网络突起纵横交错在一起形成更厚更致密的覆盖层,使NPCS膜的表面平坦化。

N-methylene phosphonic chitosans( NPCS) were synthesized by reaction of chitosan with phosphorous acid and paraformaldehyde. The structure of NPCS was characterized by FT-IR and NMR. Compared with CS,the complexing ability of Ca2 +to NPCS membrane is greatly improved. The complexation quantity is increased with increase of the p H value. At p H = 10,the complexation reaction is a first-order kinetic process. The data of XRD indicates that the crystallinity of NPCS is decreased compared with CS. However,the crystallinity of NPCS / Ca2 +complex is improved.The results of atomic force microscope( AFM) and SEM of NPCS membrane reveal that some columnar structures are formed,which make the surface more rough. However,the surface tends to be smooth and delicate after complexation with Ca2 +,and it can be clearly observed that some dendritic network protrusions of helical structure are formed on the surface. The depth of the protrusions is 275 nm and the spiral stripe distance is about 200 ~ 400 nm. The dendritic network protrusions are arranged in a crisscross pattern together to form much thicker and dense covering layers which make the membrane surface more planar.