聚苯乙烯/蒙脱土纳米复合材料的自组装行为

聚合物／层状硅酸盐（PLS）纳米复合材料由于具有常规复合材料所没有的结构、形态以有较常规聚合物基复合材料更优异的物理力学性能等而引起人们的关注^1]，但以往文献^1-3]主要报道PLS纳米复合材料的制备与性能表征，对于熔融加工过程中粘土粒子吸高分子的取向和结构研究很少。作者等^4-6]发现了剥离型聚苯乙烯（PS）／蒙脱土纳米复合材料中的剪切诱导有序结构，并采用广角X射线衍射法（WAXD）、透射电镜法（TEM）和红外二向色性法对其形成机理进行了研究。结果表明，该有序结构的主要来源是分散在PS基体中的蒙脱土初级粒子（Primary particles）内部片层的规整排列以及沿平行于样品表面方面的平面取向，PS的苯环平面平行剪切流动方向取向，而烷项链未见明显取向。本文报道该纳米复合材料的剪切诱导有序结构在升温过程中出现的自组装行为，并用原位升温X射线衍射法和红外二向色性法对蒙脱土初级粒子的规整度以及PS的苯环和烷基链在升温过程中的取向行为进行了研究，在此基础上提出了可能的形成机理。

Self-assembly Behavior in PS/ Montmorillonite Nanocomposite

A shear-induced ordered structure in an exfoliated polystyrene(PS)/clay nanocomposite is reported. Self-assembly behavior was reported for the first time of a shear-induced ordered structure in the nanocomposite. The self-assembly behavior was measured by X-ray diffraction(XRD) patterns, transmission electron microscopy(TEM), and FTIR dichroism technique. Compared with the broad amorphous peaks of the PS, a series of sharp XRD peaks were observed for the exturded PS/clay nanocomposite pellet sample, showing that an ordered sructure occurred under shear flow. The intensities of the four sharp XRD peaks of the ordered sructure decreased significantly with temperature. However, at 95 ℃, the XRD peaks increased significantly, the FTIR dichroism showing that and the phenyl ring of PS changed its orientation from parallel to perpendicular to the monmorillonite primary particles, whereas no obvious orientation of the alkyl chain of PS could be found. At 110 ℃, a disordered structure occurred for the phenyl ring. TEM images confirmed directly that the origin of the ordered structure was mainly due to the planar orientation of the primary particles of silicate layers as well as local ordered microsructure of the primary particles, induced by shear flow. Basd on these investigations, a possible mechanism was deduced for the formation of the ordered strucure induced by shear flow in the exfoliated PS/clay nanocomposite.