锌离子对壳聚糖复合膜结构和性能的影响

通过在壳聚糖溶液里加入乙酸锌制备Zn2+/壳聚糖复合膜,并利用FTIR、XRD、DSC、DMA和AFM考察了加入不同量Zn2+对壳聚糖复合膜微观结构、表面形貌、结晶性能以及热行为的影响.结果表明,壳聚糖分子中的—NH2、—OH、—NHCO—活性基团和Zn2+发生了配位反应,且随着Zn2+量的增加,有关复合膜表面的粗糙度明显增大.Zn2+的量增加到一定程度后会导致发生明显的相分离,复合膜的储能模量也随之明显下降.

Effect of Zn2+ on the Structure and Properties of Chitosan Films

The Zn~(2+)/chitosan blending system was investigated by tuning the Zn~(2+)/chitosan ratios.First,the Zn~(2+)/chitosan composite films were prepared by adding Zn(Ac)_2·2H_2O into chitosan solutions.Then the structure,surface morphology,crystallization and thermal stability of the films were characterized with FTIR,XRD,DSC,DMA and AFM measurements.The FTIR results showed that coordination reaction occurred among the groups of —NH_2,—OH,—NHCO— in chitosan and Zn~(2+),and this coordination reaction would play a crucial role in the subsequent characterizations.The coordination reaction occurred among the Zn~(2+),—NH_2 and —OH groups was corroborated strongly by the FTIR measurements.The action between Zn~(2+) and —NH_2 was evidenced by the disappearance of the 1630 cm-1 band(assigned to —NHCO—) and meanwhile the shift of the 1332 cm-1 band (assigned to ν(C—N)); and the action between Zn~(2+) and —OH was reflected by the shift of 1066 and 1025 cm-1 bands (all are assigned to ν_as(C—OH)).The subsequent XRD and DSC results indicate further that the coordination would lead not only to the decrease in CS crystallization degree but also to the variation in the orientation of zinc acetic (ZnO) crystals.In addition,with more zinc acetic added,phase separation in solutions may take place also influence the CS crystallization.As the DMA revealed,that the tremendous phase separation would result in the significant decrease in the storage modulus.The size of chitosan crystal particles and the surface roughness of Zn~(2+)/chitosan composite films increased with the content of Zn~(2+).Phase separation occurred between the chitosan and zinc acetate when the content of Zn~(2+) reached a certain level,which led to obvious reduction of storage modulus of the composite film.