比较两种丝素膜的结构、热分解机理与热力学参数  

Comparative studies of structure, thermal decomposition mechanism and thermodynamic parameters of two kinds of silk fibroin films

作　　者：刘其春 王昉[1] 李莹莹 于海洋 马青玉 顾正桂[2] Qichun Liu;Fang Wang;Yingying Li;Haiyang Yu;Qingyu Ma;Zhenggui Gu(Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023, China;School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China;School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China)

机构地区：[1]南京师范大学分析测试中心,南京210023 [2]南京师范大学化学与材料科学学院,南京210023 [3]南京师范大学物理科学与技术学院,南京210023

出　　处：《中国科学：化学》2019年第7期1014-1029,共16页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:11474166);江苏省高校自然科学基金(编号:15kJB150018)资助项目

摘　　要：本文利用氯化钙-甲酸体系制备了来源于中国和泰国家蚕的两种丝素膜。通过扫描电子显微镜、傅里叶红外光谱和X射线衍射以及热重分析技术,分别表征了膜材料的形貌、分子构象、热稳定性以及热分解机理,获得了动力学参数(活化能E和指前因子A)和热力学参数(ΔH~≠、ΔG~≠和ΔS~≠),并对其进行了比较研究。结果表明,1.5 wt%浓度体系下的丝素膜结构主要呈现β-折叠, 3.0 wt%浓度体系下的膜结构以无规线团或α-螺旋为主;3.0 wt%浓度下的膜在不同升温速率下的分解温度、活化能和活化焓均低于1.5 wt%浓度下的,后者的热稳定性优于前者;相同浓度体系下,泰国丝素膜的β-折叠含量略高于中国丝素膜,具有更好的热稳定性;通过Achar微分法和Coats-Redfern积分法计算发现,两种丝素膜在464~594 K的热分解过程都遵循二维扩散机理。The silk fibroin films from Chinese and Thai silkworms were prepared by a new method of calcium chlorideformic acid system. The films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The morphological, molecular conformation and thermal stability of the material and the thermal decomposition mechanism were obtained as well as the kinetic parameters(activation energy E, pre-exponential factor A) and thermodynamic parameters(ΔH~≠,ΔG~≠and ΔS~≠), and a compare research were performed. The results showed that the structure of silk fibroin film under 1.5 wt% concentration system mainly appeared β-sheet, and the membrane structure under 3.0 wt% concentration system was dominated by random coils or α-helix;At the different heating rate, the decomposition temperature, activation energy and activation enthalpy of 3.0 wt% concentration system were all lower than those of 1.5 wt%, and the latter has better thermal stability than the former. Under the same concentration, the β-sheet content of Thai silk fibroin film is slightly higher than that of China and it had better thermal stability. It was found by Achar differential method and Coats-Redfern integration method that the thermal decomposition process of silk fibroin film follows the cylindrical symmetry(two-dimensional diffusion) mechanism at 464~594 K.

关 键 词：丝素 分子构象 热分解机理 热力学 热分析 

分 类 号：TB383.2[一般工业技术—材料科学与工程]