Circular dichroism of optically active poly(dialkylsilane) aggregates in microcapsules.
Circular dichroism of optically active poly(dialkylsilane) aggregates in microcapsules.
复制标题
DOI：
10.1021/la060810
复制
发表时间：
2006-08
期刊：
影响因子：
--
通讯作者：
K. Terao;Noriaki Kikuchi;Takahiro Sato;A. Teŕamoto;M. Fujiki;T. Dobashi
中科院分区：
文献类型：
--
作者：
K. Terao;Noriaki Kikuchi;Takahiro Sato;A. Teŕamoto;M. Fujiki;T. Dobashi
通过在不同温度下乙醇（非溶剂）和四氢呋喃（低温缔合溶剂）中的圆二色性测量，研究了限制在微胶囊中的聚[正己基-(S)-3-甲基戊基硅烷]聚集体，以保持聚集数，并且微胶囊中的平均聚合物质量 m(p) 范围为 2 x 10(-)(16) 至 2 x 10(-)(14) g。聚硅烷样品的重均分子量 M(w) 和多分散指数（M(w) 与数均分子量之比）分别为 6.6 x 10(4) 和 1.07，对于 m(p) = 2 x 10(-)(16) g 和 1.7 x，每个胶囊中聚合物分子的平均数量估计为 1.9 x 10(3) 10(5) 对于 m(p) = 2 x 10(-)(14) g。每个聚集体的尺寸不会影响光学活性，因为在研究的 m(p) 范围内相同条件下，由此获得的圆二色性与 m(p) 成正比；另一方面，四氢呋喃中圆二色性的峰高在0～25℃之间有明显的滞后。而且，圆二色性明显反映了制备方法，即温度和溶剂；换句话说，聚合体记住了其堆叠结构的初始条件。
Poly[n-hexyl-(S)-3-methylpentylsilane] aggregates confined in microcapsules to keep the aggregation number and ranging in average polymer mass m(p) in a microcapsule from 2 x 10(-)(16) to 2 x 10(-)(14) g were studied by circular dichroism measurements in ethanol (a nonsolvent) and tetrahydrofuran (an associative solvent at low temperature) at various temperatures. The weight-average molecular weight M(w) and the polydispersity index (the ratio of M(w) to the number-average molecular weight) of the polysilane sample were 6.6 x 10(4) and 1.07, respectively, and the average number of polymer molecules in each capsule was estimated to be 1.9 x 10(3) for m(p) = 2 x 10(-)(16) g and 1.7 x 10(5) for m(p) = 2 x 10(-)(14) g. The size of each aggregate did not affect the optical activity because the circular dichroism thus obtained was proportional to m(p) under the same conditions in the investigated m(p) range; on the other hand, the peak height of the circular dichroism in tetrahydrofuran had a significant hysteresis between 0 and 25 degrees C. Moreover, the circular dichroism appreciably reflected the prepared method, that is, the temperature and solvent; in other words, the aggregates memorized the initial conditions in their stacking structures.