Choi Sung-Hwan, Newby Bi-min Zhang
Department of Chemical Engineering, The University of Akron, Akron, Ohio 44325-3906, USA.
J Chem Phys. 2006 Feb 7;124(5):054702. doi: 10.1063/1.2162534.
The effects of dynamic contact angle (thetad), between a substrate and the melt of a dewetting polymer thin film, on the evolution of rim instabilities of dewetting holes were reported. Various thetad's were achieved by covering SiOx surfaces with different coverage of octadecyltrichlorosilane. On each surface, the morphology of the dewetting holes was examined in detail as the hole grew to a certain size. Rim instabilities, in terms of undulations in both r and z directions, became more pronounced as thetad increased, under which condition, narrower and higher rims were also observed. Experimentally, atomic force microscopic scans of the rim were used to obtain the rim profile, which was predicted using thetad. The predicted rim profile was used, in combination with the analysis of Rayleigh instability of a cylindrical fluid, to interpret the rim instability. The model captures the basic trend of the rim instability dependency on thetad. The study demonstrates the importance of the substrate properties on the rim instability and the destabilization of polymer thin films during hole growth.
报道了基底与去湿聚合物薄膜熔体之间的动态接触角（θd）对去湿孔边缘不稳定性演变的影响。通过用不同覆盖率的十八烷基三氯硅烷覆盖SiO x表面来实现不同的θd。在每个表面上，当孔生长到一定大小时，详细检查了去湿孔的形态。随着θd的增加，边缘不稳定性（就r和z方向上的起伏而言）变得更加明显，在这种情况下，还观察到更窄更高的边缘。实验上，使用原子力显微镜对边缘进行扫描以获得边缘轮廓，该轮廓是根据θd预测的。预测的边缘轮廓与圆柱流体的瑞利不稳定性分析相结合，用于解释边缘不稳定性。该模型捕捉了边缘不稳定性对θd的依赖的基本趋势。该研究证明了基底性质对边缘不稳定性以及孔生长过程中聚合物薄膜失稳的重要性。
