Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, USA.
J Chem Phys. 2012 Jul 28;137(4):044703. doi: 10.1063/1.4736571.
Using full atomistic classical molecular dynamics simulations, the interfacial properties of free-standing poly(3-hexylthiophene) (P3HT) films have been investigated. The orientations of different parts of the P3HT chain and the surface tensions of the films were calculated in a temperature range of 540 K-600 K. At the liquid/vacuum interface, the P3HT chain shows ordering by exposing hexyl groups at the interface, while the chain backbone lays flat with the thiophene ring preferentially tilt toward the surface. At the interface, the terminal methyl groups of hexyl side chains are in excess compared to the methylene groups or thiophene rings. The surface tension of P3HT in its melt state shows similar temperature dependence to that of polymers that have long alkyl side chains. The surface tension values are comparable to those polymers that expose methyl or methylene groups on the surface. The surface tension values determined for the melt state are lower than the experimental reported values for crystalline P3HT films, as expected.
利用全原子经典分子动力学模拟，研究了自由支撑的聚（3-己基噻吩）（P3HT）薄膜的界面性质。在 540 K-600 K 的温度范围内，计算了 P3HT 链的不同部分的取向和薄膜的表面张力。在液体/真空界面处，P3HT 链通过在界面处暴露己基来进行有序排列，而链主链则与噻吩环一起平放在表面上，噻吩环优先倾斜到表面。在界面处，与亚甲基或噻吩环相比，己基侧链的末端甲基基团过剩。P3HT 在其熔体状态下的表面张力与具有长烷基侧链的聚合物具有相似的温度依赖性。表面张力值与那些在表面上暴露甲基或亚甲基基团的聚合物相当。对于熔体状态确定的表面张力值低于实验报道的结晶 P3HT 薄膜的表面张力值，这是预期的。
