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首页> 外文期刊>Liquid Crystals: An International Journal in the Field of Anisotropic Fluids >Dynamic investigations of liquid crystalline elastomers and their constituents by H-2 NMR spectroscopy
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Dynamic investigations of liquid crystalline elastomers and their constituents by H-2 NMR spectroscopy

机译：H-2 NMR光谱法动态研究液晶弹性体及其成分的动态研究

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摘要

Several side-chain liquid single crystalline elastomers (LSCEs) were investigated by means of H-2 NMR spectroscopy focusing on the temperature dependence of the spectral line width and spectral shape, as well as the T-dependence of spin-lattice and spin-spin relaxation times (T-1 and T-2). All measurements were performed at the Larmor frequency of 76.753 MHz for 2H. The LSCEs were prepared in the form of monodomain films by using either H-2-labelled monomers (or co-monomers), 2H-labelled cross-linkers or 2H-labelled molecular probes free to diffuse in the LSCE matrix. In all cases, deuterons are on the phenyl moiety. The main features of the measured H-2 NMR properties (static and dynamic ones) in these different cases were discussed and compared with those of low-molecular-weightmesogens (i.e. the same molecules used as monomers or co-monomers in the side-chain LSCEs) in the nematic and smectic A phases. Among all investigated LSCE samples, those H-2-labelled on the cross-linker sites present distinct properties either on the 2H NMR spectral line width and spectral shape in the paranematic and in the nematic phases, which can be interpreted in terms of director reorientational dynamics in the intermediate-slow motional regime, taking into account the inherent local director misalignment of LSCEs.
机译：通过H-2 NMR光谱研究了几种侧链液单晶弹性体（LSCES），其针对光谱线宽和光谱形状的温度依赖性，以及旋转晶格和旋转旋转的T依赖性放松时间（T-1和T-2）。所有测量均为76.753MHz的拉马力频率进行2小时。通过使用H-2标记的单体（或共聚单体），2H标记的交联剂或2H标记的分子探针以自由扩散在LSCE基质中，以单颗粒膜的形式制备LSCE。在所有情况下，氘核在苯基部分上。讨论了这些不同病例中测量的H-2 NMR性质（静态和动态）的主要特征，并与低分子量重量（即，与单体或侧链中的共聚单体相同的分子相比LSCES）在甲目和近次阶段。在所有调查的LSCE样品中，在交联剂位点上标记的那些H-2标记的存在于促使和向列阶段的2H NMR光谱线宽和光谱形状上存在明显的性质，其可以在导演重新定位方面解释中间慢动动制度的动态，考虑到LSCE的固有本地导演未对准。

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