Molecular Structure Modification and Characterization of Langmuir-Blodgett Films made of Amphiphilic Polysilane through Ionizing Radiation

近十年来，聚硅烷衍生物作为一种具有电子半导性、非线性光学性质、高空穴漂移迁移率等特性的基本聚合物材料，引起了人们的极大兴趣。聚硅烷衍生物的这些有趣的物理性质本质上归因于硅主干上的sigma电子的离域。然而，很难说共轭体系延伸到整个硅骨架上，因此，将一个硅骨架分成几个共轭硅片段是普遍共识。问题是决定分子间空穴输运现象的是分子间空穴输运现象还是有趣的跳跃现象。在本工作中，以聚(甲基苯基硅烷)：PMPS和聚(β-苯基甲基硅烷)：PMbeta-PHS为起始聚硅烷，通过氯甲基化PMPS或PMbeta-PHS与(CH3)2C_nH&lt；2n+1&gt；N，氯阴离子交换得到了两亲聚硅烷。这些堆积的LB膜的光学光谱表明它们的吸收光谱发生了压电致变色位移。这些两亲性聚合物的高密度激发表现出极化致密的LB膜(400-500 nm宽发射)和无规溶剂浇铸的LB膜(580-600 nm另一个较长的发射带)的发射光谱不同。这两个发射带分别归属于氨基与硅骨架之间的分子内激基缔合物和分子间激基缔合物的形成。结果表明，与非晶态膜相比，LB膜的能量弛豫过程不同，两亲性聚硅烷LB膜的分子间能量传递可以忽略不计。

Since the last decade, polysilane derivatives have been elicited great interest as fundamental polymer materials showing lelctronic semiconductivity, nonlinear optical property, high hole drift mobility, and so on. These interesting physical properties of polysilane derivatives are essentially attributed to the delocalization of sigma-electrons of the Si backbone. However, it is hardly to say that the conjugated system is extended over the entire silicon skeleton, therefore, it is common consensus that a silicon skeleton is divided into several conjugated silicon segments. The question is which determine the hole transport phenomenon in intermolecular or interesting hopping. Then, electronic and optical characterization of highly polarized polysilane films may predict the electronic structure of silicon skeleton and inter-and intra-molecular relation.In the present work, poly (methylphenylsilane) : PMPS and poly (beta-phenethylmethylsilane) : PMbeta-PhS employed as an initial polysilane, and amphiphilic polysilanes were obtained by the salt formation between chloromethylated PMPS or PMbeta-PhS and (CH_3) _2C_nH_<2n+1>N.Chlorine anion exchanged by several kinds of counter anions and the polymer piled up to 1000 layrs. Optical spectroscopy of these piled LB films represented piezochromic shifts in their absorption spectra. High dense excitation of these amphiphilic polymers showed a deference in emission spectra of polarized and dense LB films (400-500nm broad emission) and random solvent casted films (another longer emission band at 580-600nm). These two emission bands were assigned to intramolecular exciplex formation between ammonium groups and silicon skeleton and intermolecular one, respectively. It can be condluded that energy relaxation processes are different in LB films in comparison with amorphous films, intermolecular energy transfer can be neglected in LB films of amphiphilic polysilanes.