【作者】 马辉；

【导师】 毛志平；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2013， 博士

【摘要】 有机-无机复合材料在光学、电子、生物、催化、膜材料以及机械等很多方面具有很高的应用价值。近年来,由于其巨大的工业应用和理论研究价值,受到越来越多的重视。在有机-无机复合材料的构筑中,层状硅酸盐具有低含量、制备工艺简单、天然的纳米结构、极大的比表面积、强的界面作用等特点,这使得聚合物/层状硅酸盐复合材料成为应用最广且最有工业化前途的有机-无机复合材料。目前,世界各国对聚合物/层状硅酸盐复合材料的研究工作异常活跃,相继开发了许多高性能、新功能的复合材料,包括阻燃材料、阻隔材料、光学材料、缓释剂、抗菌剂、生物材料等,均具有极大的发展潜力和实用意义。众多研究表明,实现无机-有机两相体系在纳米尺度上的规律组装,复合材料的性能将得到极大提升。科学工作者不断地展开科技创新,利用新工艺、新方法制备各种复合材料,从而取得了长足的进步,得到了不同形态的组装体。但是,科学工作者研究所得组装体多数是通过硅酸盐的物理键合力组装形成,很少是通过硅酸盐-有机聚合物两相形成共价键制备硅酸盐组装体,并且我们也没有检索到具有说服力的文献,以说明这类组装体的宏观性能如何,微观结构与宏观性能存在着何种关系。为了认知这些问题,本文进行了如下实验工作,并取得了一系列研究成果：(1)探讨了蛭石片晶有机修饰的可行性选择商品化蛭石作为原料,对其进行研磨、插层以及剥分处理,制备剥分蛭石。利用硅烷偶联剂KH-550以及KH-560对剥分蛭石进行有机修饰,并探讨硅烷偶联剂用量与改性蛭石增重量的关系。采用红外光谱仪(FTIR)、光电子能谱(XPS)、热重分析(TGA)探讨蛭石片层改性前后结构的变化。实验结果表明,利用硅烷偶联剂可对蛭石片晶进行有机修饰,得到两种改性蛭石：氨基化蛭石以及环氧化蛭石。硅烷偶联剂体积用量为0.75ml时,改性蛭石的增重量为1.62%。改性蛭石的增重量随硅烷偶联剂用量的增加而增加,当硅烷偶联剂用量为5.00ml时,改性蛭石的增重量最高可以达到6.06%。(2)探讨了有机修饰蛭石与有机单体的组装行为以及蛭石片晶的组装机理将66盐与氨基化蛭石混合,然后采用原位聚合的方法制备66盐/氨基化蛭石复合材料,对制得的复合材料进行红外(FTIR)、光电子能谱(XPS)以及透射电镜(TEM)以及扫描电子显微镜(SEM)分析,在此基础上认识改性蛭石的组装行为以及其与有机高聚物的相互作用机理。实验结果表明,氨基化蛭石的氨基与66盐的羧基发生反应,形成了共价键,使得有机分子链嫁接在蛭石片层表面形成高分子刷。在高分子刷的作用下,蛭石片晶在有机相内部进行组装,形成了组装体。当复合材料中蛭石的百分含量不同发生变化,蛭石在有机相中呈现出不同的组装结构(线状、网状以及树枝状分布)。高分子刷的密度增大时,无机片晶的组装形态也发生了很大的变化,从线状分布变为层状分布。通过控制蛭石表面官能团数量,可以得到两种高粘土添加量复合体系组装体：长叶状以及棒状组装体。利用乳酸以及环氧化蛭石采用原位聚合的方法制备了乳酸基聚合物/环氧化蛭石复合材料,对制得的复合材料进行红外(FTIR)、光电子能谱(XPS)以及透射电镜(TEM)分析,探讨了改性蛭石在乳酸相中的组装行为及组装机理。实验结果表明,乳酸基聚合物同样可以在改性蛭石表面形成高分子刷,促使蛭石片晶进行组装,得到棒状形态的组装体。(3)探讨了组装材料的结构与性能利用扫描电子显微镜(SEM)以及原子力显微镜(AFM)对66盐/氨基化蛭石复合材料进行弹性模量分析,并对复合材料的结晶行为以及拉伸性能进行了探讨。棒状以及饼状两种组装体的弹性模量测试结果表明,无机片层与有机单体两相体系进行有序组装后,组装体的模量数值远高于其单组份的弹性模量数值。复合材料的结晶行为以及拉伸性能测试表明,相对于纯聚合物体系,含有组装体的复合材料结晶行为以及拉伸性能有了较大改善。利用原子力显微镜(AFM)、激光扫描聚焦显微镜测试(CLSM)、偏光显微镜测试(POM)以及热重分析(TGA)对乳酸基聚合物/环氧化蛭石复合材料分别进行了弹性模量、生物相容性、结晶行为以及热稳定性能分析。实验结果表明,乳酸系组装体的弹性模量同样高于其单组份的弹性模量,造骨细胞在材料表面表现出较强的增殖能力,具有应用于生物领域的潜力。与纯聚合物相比,含有组装体的复合材料结晶速度更快,晶粒更小,同时分解温度有了很大提高。(4)利用计算模拟技术对蛭石的组装行为以及影响因素进行探讨利用模拟软件(Materials Studio)建立了PA66/AMVMTs与HA/AMVMTs两种复合模型,并对其进行了动力学计算。探讨了两种复合模型的界面结构变化,并研究了影响无机片晶自组装进程的因素。实验结果表明,与PA66/AMVMTs模型相比,HA/AMVMTs模型的两相相容性更好,界面结构更加稳定。另外,蛭石表面嫁接的有机链长度与密度是影响其组装进程的两个重要因素。蛭石表面有机链长度与密度增加时,无机片晶模型的组装趋势更加明显。此结论为将来设计与制备新型复合材料提供了一定的理论基础。更多还原

【Abstract】 Recently, organic-inorganic composites have attracting more interest due to their industrial applications and the exploring of theory, including optics, electrics, organisms, catalysis, membrane materials and mechanics. Among the various kinds of organic-inorganic hybrids, polymer/clay composites have become the most potential for applications because of the very low cost of clay components, relatively simple preparation, their nanometer size that provides unique features and extraordinarily high surface area.As far as we are aware, polymer/clay composites become more widely studied in academic, government and industrial laboratories. Based these studies, many composites with high performance and new functional properties were prepared, including the fire-retardant, barrier materials, optical materials, controlled-release materials, antibacterial agent and medical materials, which exhibited the potential or industrial applications.The study has demonstrated that the toughening of the composites has the formidable increase when the juxtaposition of inorganic and organic matrix was realized to form the orderly nanostructure. Thus, the new procedure and method were developed to form the novel composites and kinds of assemblies with different morphologies were obtained.However, none of the previous techniques reports the possibility for generating polymer-clay assemblies based on chemical bindings by in-situ polymerization, and the structure and properties of the assemblies were confused. Herein, the structure and properties of the composites were explored and the formidable results were showed as follows:(1) The possibility of the modification of VMTsThe exfoliated vermiculites (VMTs) were prepared through the grinding, intercalation and exfoliation of commercial VMTs. Exfoliated VMTs were chemical modified by the silane coupling agent KH-550and KH-560and the relationship between the usage of silane coupling agent and the loading ratios of modified VMTs. The change of the structure of VMTs before and after the chemical modification was studied by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA). The results indicated that two kinds of modified VMTs, including amino-modification and epoxy-modification VMTs, were prepared after the chemical modification of silane coupling agent. When the usage of silane coupling agent was0.75ml, the loading ratio of modified VMTs was1.62%. The loading ratio of modified VMTs was increased with the increasing of the usage of silane coupling agent. The loading ratio of modified VMTs could increase to6.06%when the usage of silane coupling agent was5.00ml.(2) The assembly of modified VMTs and polymer monomers and their assembly mechanismThe hexamethylene adipamide/amino-modified VMTs (HA/AMVMTs) composites was prepared through the in-situ polymerization of hexamethylene adipamide and modified VMTs. The assembly of the modified VMTs and interaction between the modified VMTs and polymers were explored by FTIR, XPS, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The results showed that the polymer brush was formed onto the VMTs through the covalent bindings of-NH2and-COOH, resulting in the assembly of modified VMTs in the polymer matrix. The loading ratios and modifying ratios of the VMTs played an important role in their self-assembly:with the increasing of the loading ratios, the fiber-, network-and dendritic-like assemblies were observed; with the increasing of polymer brush, the morphology of the assemblies changed from fiber-like to layered-like. For the high ratios of VMTs, leaf-like and rod-like assemblies were prepared by controlling the quantities of the polar groups on the VMTs.The lactic acid/expoxy-modified VMTs (LA/GMVMTs) composites were prepared through the in-situ polymerization of lactic acid and modified VMTs. The assembly of the modified VMTs in the poly (lactic acid) and assembly mechanism of VMTs were explored by FTIR, XPS and TEM. The results showed that the poly (lactic acid) was also formed onto the modified VMTs, resulting in the assembly of modified VMTs in the polymer matrix, the rod-like assemblies were obtained.(3) The structure and properties of the compositesThe Young’s modulus of the HA/AMVMTs assemblies was characterized through SEM and Atomic Force Microscopy (AFM) and the crystallization behavior and tensile properties of the composites were tested. The results showed that the Young’s modulus of the assemblies was higher than that of their constituents after the assembly of inorganic and organic materials. The crystallization behavior and tensile properties of the composites with assemblies were greatly improved compared with the pure polymer system.The Young’s modulus, cytocompatibility, crystallization behavior and thermal stabilities of the LA/GMVMTs composites were characterized through AFM, Confocal laser scanning microscope (CLSM), Polarizing Optical Microscope (POM) and TGA test, respectively. The results showed that the Young’s modulus of the assemblies was also higher than that of their constituents and cells proliferated and reached confluence on the surface of the assemblies, which indicated that the assemblies exhibited the potentiality of biomaterials applications. Compared with pure polymer system, the crystallization rate of the composites became faster and crystallization size of the composites became smaller, while the decomposition temperature of the composites was greatly improved.(4) The exploring of the assembly of VMTs by Molecular Dynamic simulationsBoth PA66/AMVMTs and HA/AMVMTs corresponding models were simulated and calculated by the use of Materials Studio. The interface structure of two models and influence factors on the assembly process of VMTs were studied. The results showed that the HA/AMVMTs model exhibited a better compatibility and higher stability of organic and inorganic matrix compared with PA66/AMVMTs model. In addition, the height and density of polymer molecules on the VMTs had an important role in the assembly of VMTs. With the brush height and density increasing of polymer molecules, the VMTs models were more easily self-assembled. The theory basis on the design and preparation of novel composites was provided based on these results.更多还原