Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Petersenstrasse 20, D-64287 Darmstadt, Germany.
J Phys Chem B. 2009 Nov 5;113(44):14596-603. doi: 10.1021/jp906447a.
The thermal conductivity (lambda) of stretched amorphous atactic polystyrene (PS) swollen in supercritical carbon dioxide (sc CO(2)) has been investigated over a wide temperature, pressure, and concentration range. Nonequilibrium molecular dynamics simulations with a full atomistic force-field have been employed to calculate the thermal conductivity of neat stretched PS and of different mixtures of supercritical CO(2) with stretched PS. As the energy transport in PS parallel and perpendicular to the stretching direction differs, an anisotropy in the thermal conductivity occurs. The magnitude of lambda is enhanced with an increasing number of carbon-carbon backbone bonds oriented parallel to the direction of the heat transport. The degrees of freedom in the side chain of the polymer are rather unimportant for the thermal conductivity. To understand the conditions leading either to an equivalence or nonequivalence of the system degrees of freedom for the heat transport, we have analyzed lambda of PS, CO(2), binary PS-CO(2) mixtures and other model systems as a function of the bond constraints in the computational model. Furthermore, we have commented on differences in the thermal conductivity provided either by a vibrational energy transfer or by collisions.
已在很宽的温度、压力和浓度范围内研究了在超临界二氧化碳（scCO2）中溶胀的拉伸无规聚苯乙烯（PS）的热导率（lambda）。采用全原子力场的非平衡分子动力学模拟已被用于计算纯拉伸 PS 和不同的超临界 CO2 与拉伸 PS 的混合物的热导率。由于 PS 中平行和垂直于拉伸方向的能量传递不同，因此热导率会出现各向异性。lambda 的大小随平行于热传输方向取向的碳-碳主链键的数量增加而增加。聚合物侧链的自由度对热导率的影响不大。为了理解导致系统自由度在传热方面等效或不等效的条件，我们已根据计算模型中的键约束分析了 PS、CO2、PS-CO2 二元混合物和其他模型系统的 lambda。此外，我们还对由振动能传递或碰撞提供的热导率的差异进行了评论。
