Molecular Assemblies in Multicomponent Linear Chain Solids

为了表征二元和多组分聚亚甲基链阵列内的固态分子相互作用，定向单晶微晶的电子衍射数据将被用来阐明它们的晶体结构。 这将提供一个独特的机会，以揭示信息（例如，包装对称性，晶胞尺寸，共存的类似晶体多晶型物或交替晶体结构，住宿的非重叠分子体积），以前隐藏的粉末衍射研究，由于反射重叠。 在这个实验室开发的技术将提供可靠的强度数据，从最翔实的预测单位细胞，以进行定量的直接结构分析。 低剂量电子显微镜晶格成像也将描绘界面相边界。 将研究影响固溶体稳定性的因素（链长差异和长度分布，杂基和分支夹杂物），无论是稳定的lameries，以及不完全分离lameries，包括长“桥分子”。 在可熔性间隙内的两组分和三组分亚稳固溶体的相分离的过程将通过电子晶体学来表征，以定义最终固体的晶体堆积，以便辨别暗示扩散路径的共同特征。共晶固体的晶体学表征将识别跨越相边界的界面相互作用，测试这些接触域之间外延相互作用的一般发生。这些聚合物材料的分子和结构表征对于理解和优化它们的性质是重要的。***

To characterize the solid state molecular interactions within binary and multicomponent polymethylene chain arrays, electron diffraction data from oriented single microcrystals will be employed to elucidate their crystal structures. This will provide a unique opportunity to uncover information (e.g. packing symmetry, unit cell dimensions, co-existence of similar crystalline polymorphs or alternate crystal structures, accommodation of non-overlap molecular volumes) previously hidden to powder diffraction investigations due to reflection overlap. Techniques developed in this laboratory will provide reliable intensity data from the most informative projections of the unit cell, in order to carry out quantitative direct structure analyses. Low dose electron microscopic lattice imaging will also depict interfaces at phase boundaries. Factors influencing the stabilization of solid solutions (chain length differences and length distribution, heterogroup and branch inclusions) will be studied, both for stable lamellae as well as incompletely separated lamellae that include long 'bridging molecules'. The progress of phase separation for two- and three-component metastable solid solutions within a miscibility gap will be characterized by electron crystallography to define the crystal packing of the final solids, in order to discern common features that would suggest a diffusion path. Crystallographic characterizations of eutectic solids will identify interfacial interactions across phase boundaries, testing the general occurrence of epitaxial interactions between these contacting domains.%%%The molecular and structural characterization of these polymeric materials is important in understanding and optimizing their properties. ***