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Synthesis and Properties of Highly Aligned Polyacetylene Prepared by using Smectic Liquid Crystal as a Solvent.

以近晶液晶为溶剂制备的高度取向聚乙炔的合成及性能。

基本信息

批准号：
03650739
负责人：
AKAGI Kazuo
金额：
$ 1.28万
依托单位：
Institute of Materials Science, University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Polymerization of acetylene has been carried out under anisotropic reaction field that is generated by equi-molar mixture of two kinds of smectic liquid crystals used as solvent for Ziegler-Natta type catalyst composed of tetra-n-butoxytitanium, Ti(O-n-Bu)_4, and triethylalumium, AlEt_3. The smectic liquid crystals have a cyclohexylphenoxy moiety as a mesogenic core, and alkyl chains as terminal groups, as shown below.As a result, we succeeded in a synthesis of as-grown directly aligned polyacetylene film in the smectic liquid crystal phase. Measurements of SEM (scanning electron microscope), however, indicated that the fibrils, bundles of polyene chains, are not uniformly aligned. Nevertheless, the microscopic alignment of fibrils enabled the iodine-doped film to attain high electrical conductivity of 1.4 x 10^4 S/cm, which is comparable to those of polyacetylene films prepared by nematic liquid crystal.Next, we have applied the solvent-free polymerization method recently developed for synthesis of highly tensile and stretchable polyacetylene film to the present liquid crystal method, in order to prepare as-grown aligned film with mechanical stretchability. The Ti(O-n- Bu)_4-AlEt_3 catalyst was first prepared without solvent at room temperature and aged at higher temperature of 150 ﾟC for 1 hour. Then to the catalyst was added an equi-molar mixture of nematic or smectic liquid crystals. The film obtained was indeed improved in fragility, but it showed no notable stretchability in spite of usage of high-temperature aged catalyst. This may be due to low concentration of the catalyst, which is an inevitable restriction to keep the liquid crystalline phase.

以四正丁基钛（Ti(O-n-Bu)_4）和三乙基铝（AlEt_3）组成的Ziegler-Natta型催化剂为溶剂，在两种近晶液晶等摩尔混合物的各向异性反应场下进行了乙炔的聚合。近晶液晶以环己基苯氧基部分为介生核心，烷基链为端基，如下图所示。结果，我们成功地在近晶液晶相中合成了生长的直接排列聚乙炔薄膜。然而，扫描电镜（SEM）的测量表明，原纤维，多烯链束，并不是均匀排列的。然而，原纤维的微观排列使得碘掺杂薄膜获得了1.4 x 10^4 S/cm的高电导率，这与用向列液晶制备的聚乙炔薄膜相当。接下来，我们将最近开发的用于合成高拉伸和高拉伸聚乙炔薄膜的无溶剂聚合方法应用于目前的液晶方法，以制备具有机械拉伸性的生长排列薄膜。首先在室温下无溶剂制备Ti(O-n- Bu)_4-AlEt_3催化剂，然后在150℃高温下时效1小时。然后在催化剂中加入向列型或近晶液晶的等摩尔混合物。尽管使用高温老化催化剂，得到的薄膜的脆性确实有所改善，但拉伸性能没有明显改善。这可能是由于催化剂浓度低，这是保持液晶相不可避免的限制。