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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Structure and Dynamics of a Bisurea-Based Supramolecular Polymer in n-Dodecane
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Structure and Dynamics of a Bisurea-Based Supramolecular Polymer in n-Dodecane

机译：正十二烷中双脲基超分子聚合物的结构和动力学

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摘要

The structure and dynamics of a supramolecular polymer formed by a bisurea-type compound, 2,4-bis(2-ethylhexylureido)toluene (EHUT), in an apolar solvent, n-dodecane (C_(12)), were examined in detail. The EHUT/ C_(12) organo-gel system forms long, dynamic chain-like supramolecular polymers, which lead to an entangled network showing remarkable viscoelastic behavior with two major relaxation modes. A slow relaxation mode with an approximately constant relaxation time, τ_s, was observed in a flow region and the other, fast, relaxation mode with a time τ_(F1) (<τ_s) was observed in a high-frequency range. Because no dielectric relaxation behavior was observed over a frequency region including the mechanical τ_s and τ_(F1) relaxation modes, the formed supramolecular polymer does not possess any total dipole moment due to antiparallel intermolecular hydrogen bonding of the two ureido groups of each EHUT unit. A structural model for the supramolecular polymer formed in EHUT/C_(12) is proposed based on force-field simulations. This proposed model is consistent with all the experimental data concerning this system: flow birefringence measurements, dielectric spectroscopy, SANS, and FTIR.
机译：详细研究了由双脲型化合物2,4-双（2-乙基己基脲基）甲苯（EHUT）在非极性溶剂正十二烷（C_（12））中形成的超分子聚合物的结构和动力学。 。 EHUT / C_（12）有机凝胶体系形成长的，动态链状超分子聚合物，这导致缠结的网络表现出显着的粘弹性行为，并具有两种主要的松弛模式。在流动区域中观察到具有近似恒定的弛豫时间τ_s的慢速弛豫模式，而在高频范围中观察到具有时间τ_（F1）（<τ_s）的另一快速弛豫模式。由于在包括机械τ_s和τ_（F1）弛豫模式的频率范围内未观察到介电弛豫行为，因此，由于每个EHUT单元的两个脲基的反平行分子间氢键键合，形成的超分子聚合物不具有任何总偶极矩。基于力场模拟，提出了在EHUT / C_（12）中形成的超分子聚合物的结构模型。该提议的模型与有关该系统的所有实验数据一致：流双折射测量，介电谱，SANS和FTIR。

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