精密聚乙烯:形态变化作为基分支大小的函数
Giovanni Rojas1, Bora Inci, Yuying Wei
1Center for Macromolecular Science and Engineering, The George and Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA.
Journal of the American Chemical Society
|November 7, 2009
概括
精密分支聚乙烯合成可以控制晶体形态. 分支的大小决定了它是否集成到晶体单元细胞中,从而影响了聚合物特性.
科学领域:
- 聚合物化学 聚合物化学
- 材料科学 材料科学 材料科学
- 晶体学 晶体学是指结晶学.
背景情况:
- 传统的聚乙烯链聚合法限制了对聚合物微结构的控制.
- 转化复合凝结为精确设计的聚合物架构提供了一条途径.
- 了解分支对聚乙烯形态的影响对于开发先进材料至关重要.
研究的目的:
- 为了研究精密分支对聚乙烯晶体形态的影响,使用转化聚凝.
- 为了将分支的大小和位置与单元细胞结构和相位行为 (晶体与无形) 相关联.
- 探索形态控制和聚合物热特性之间的关系.
主要方法:
- 合成具有不同精度分支 (甲基到亚达曼) 的独特对称二烯单体.
- 环开转化聚合 (ROMP) 后进行化,以产生精密分支聚乙烯.
- 使用先进的分析技术,对单体,中间体和最终聚合物进行全面的结构性表征.
主要成果:
- 转化聚凝使得聚乙烯晶体单元细胞结构的精确控制成为可能,从orthorhombic转变为triclinic.
- 聚合物形态是可调节的:小分支 (甲基,乙基) 纳入单元细胞,而较大的分支 (基及以上) 被排除在外.
- 从单元细胞中排除的分支没有影响化温度,无论分支的大小如何,即使是亚达曼基.
结论:
- 通过转化聚凝合成的精密分支聚乙烯提供了前所未有的对晶体形态的控制.
- 树枝的大小是将其纳入或排除在聚乙烯单元细胞中的关键决定因素.
- 这种形态控制策略提供了一种方法,可以将热特性与聚乙烯的分支特征脱.
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