甲壳素/丝素蛋白复合薄膜结晶特性变化研究

Study on the Variation of Crystal Properties of Chitin/Silk Fibroin Biocomposite Films

基于甲壳纲壳体角质层组成成分的仿生启示,以甲壳素(CT)和丝素蛋白(SF)两种天然高分子为主要原料,通过流延法在不同配比及干燥条件下(常规和真空)制备CT/SF复合薄膜,采用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、紫外-可见分光光度计(UV-Vis)、热重分析仪(TG)和X射线衍射仪(XRD)和力学试验机等表征手段研究复合薄膜的结晶特性及其相关性能变化。结果表明:随着m(CT)∶m(SF)从1∶4变化到4∶1,在常规干燥条件下,复合膜的晶体表观形貌从松散的“点线辐射状”逐步过渡为稠密的“丝网状”;在真空干燥条件下,薄膜表观晶体形貌从“雪花状”过渡到“蠕虫状”,再到“点线状”。当m(CT)∶m(SF)为4∶1时,干燥条件对复合膜晶形的微观形貌影响最大,从常规干燥条件下的“叠层鳞片状”转变为真空干燥条件下的“仙人球状”,相同比例下不结晶的复合膜在微观下出现直径约60 nm的微晶。在可见光波长范围大于500 nm时,m(CT)∶m(SF)为1∶4的复合膜在常规干燥下的平均透过率最高,为97.3%。在真空干燥条件下m(CT)∶m(SF)为4∶1时制备的不结晶复合膜综合力学性能和热稳定性较佳,其拉伸强度和断裂伸长率分别为1.28 MPa和134%。

Chitin (CT) and silk fibroin (SF) were selected as raw materials inspired by the chemical component of crustacean shell cuticle. The CT/SF biocomposite films were prepared by a facile casting method with the various CT/SF ratios and drying conditions (conventional and vacuum drying). The crystalline properties and the variation of other related characteristics for the biocomposite film were characterized by SEM,FTIR,UV-Vis,TG,XRD and electronic mechanical testing machine. The results show that as the ratio of m (CT):m (SF) varies from 1:4 to 4:1,the crystal appearance of the CT/SF biocomposite film gradually transforms from a loose‘radial dotted line’to a dense‘filiform net’under the conventional drying,while from“snow flower-like”to“worm-like”and then to“dotted line”under the vacuum drying. The drying condition plays a significant role on the variation of micro-morphology of the crystals of the biocomposite film when the ratio of m (CT):m (SF) is 4:1,changing from the‘scaly layer’under the conventional drying to the‘cactus ball’under the vacuum drying. Meanwhile,some microcrystals with a diameter of about 60 nm appear in the biocomposite film without crystallization at the same ratio. The biocomposite film with a m (CT):m (SF) ratio of 1:4 under the conventional drying exhibits the highest average transmittance (97. 3%) when the wavelength of visible light is beyond 500 nm.The non-crystalline biocomposite film with the m (CT):m (SF) ratio of 4:1 under the vacuum drying shows the optimum comprehensive mechanical properties and thermal stability,corresponding to the tensile strength and elongation at break of 1. 28 MPa and 134%,respectively.