等规聚苯乙烯单链单晶的结构和耐辐照性能

Structure of single-chain single crystals of isotatic polystyrene and their radiation resistance

利用电子衍射（ED）和高分辨电子显微（HREM）技术，研究等规聚苯乙烯（i－PS）单链单晶的结构．纳米级的单链单晶具有很强的耐电子辐照性能．按照i－PS的晶胞能对ED图中的衍射环和HREM像中的晶格条纹进行晶面指标化，但发现低指数衍射缺失．由于单链单晶的尺寸很小，电子辐照所产生的次级电子可以逸出晶体，使辐照损伤大大减小．另外，单链单晶存在着较少的低指数晶面，未能产生足够的衍射强度，使低指数晶面的衍射缺失．单链单晶对电子辐照稳定，在室温下，可得到高分辨晶格条纹象，这为研究高分子晶体的结构开辟了新的实验方法．

The structure of the single-chain single crystals of isotactic polystyrene (i-PS)was investigated by electron diffraction (ED) and high resolution electron microscopy(HREM ). The nanoscale single-chain single crystals were found to be very stable to electronirradiation. According to the unit cell of i-PS crystals, the reflection rings in ED pattern andthe lattice fringes in HREM images could be indexed, but the lower-index diffractions werenot found. It is proposed that the single-chain single crystals are very small, thus secondaryelectrons may be allowed to escape and radiation damage is highly reduced, and that there areless lower-index lattice planes in the single-chain single crystals to provide sufficient diffraction intensity for recording. HREM images can be achieved at room temperature in the caseof single-chain single crystals because of its stability to electron irradiation, therefore, thismight be a novel experimental approach to the study of crystal structure of macromolecules.