School of Engineering and Information Technology , Murdoch University , Murdoch 6150 WA , Australia.
Langmuir. 2018 Apr 17;34(15):4526-4534. doi: 10.1021/acs.langmuir.8b00257. Epub 2018 Apr 5.
The aim of this study is to link polytetrafluoroethylene (PTFE) surface characteristics with its wetting properties in the nanoscale. To do this using molecular dynamics (MD) simulation, three series of rough PTFE surfaces were generated by annealing and compressing and next characterized by the application of the MD version of the atomic force microscopy (AFM) method. The values of specific surface areas were additionally calculated. The TIP4P/2005 water model was used to study the wetting properties of obtained PTFE samples. The simulated water contact angle (WCA) value for the most flat (but slightly rough) sample having PTFE density is equal to 106.94°, and it is close to the value suggested for a perfect PTFE surface on the basis of experimental results. Also, the changes in the WCA with PTFE compression are in the same range as experimentally reported. The obtained MD simulation results make it possible to link, for the first time, the WCA values with the surface MD-AFM root-mean-square roughness and with the PTFE density. Finally, we show that for PTFE wetting in the nanoscale, the line tension is negligible and the Bormashenko's equation reduces to the Cassie-Baxter (CB) model. In fact, our simulation results are close to the CB mechanism.
本研究旨在将聚四氟乙烯（PTFE）表面特性与其纳米尺度下的润湿性联系起来。为此，我们使用分子动力学（MD）模拟，通过退火和压缩生成了三组粗糙 PTFE 表面，并用 MD 版原子力显微镜（AFM）方法对其进行了表征。此外，还计算了比表面积的值。我们使用 TIP4P/2005 水模型研究了所得到的 PTFE 样品的润湿性质。最平整（但略有粗糙）的 PTFE 密度样品的模拟水接触角（WCA）值等于 106.94°，接近根据实验结果得出的理想 PTFE 表面的建议值。此外，WCA 随 PTFE 压缩的变化范围与实验报道的相同。所得的 MD 模拟结果首次将 WCA 值与表面 MD-AFM 均方根粗糙度和 PTFE 密度联系起来。最后，我们表明，在纳米尺度下 PTFE 的润湿中，线张力可以忽略不计，Bormashenko 方程简化为 Cassie-Baxter（CB）模型。实际上，我们的模拟结果与 CB 机制非常接近。
