Chen Ying, Wang Zilu, Kulkarni Manish M, Wang Xiaoteng, Al-Enizi Abdullah M, Elzatahry Ahmed A, Douglas Jack F, Dobrynin Andrey V, Karim Alamgir
Department of Polymer Engineering and Department of Polymer Science, University of Akron, Akron, Ohio 44325, United States.
Center for Nanosciences, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India.
ACS Omega. 2018 Nov 13;3(11):15426-15434. doi: 10.1021/acsomega.7b01116. eCollection 2018 Nov 30.
The surface relief structure of polymer films over large areas can be controlled by combining nanoscale imprinting and microscale ultraviolet-ozone (UVO) radiation, resulting in hierarchical structured surfaces. First, nanoscale patterns were formed by nanoimprinting elastomer [poly(dimethylsiloxane) (PDMS)] films with a pattern on a digital video disk. Micron-scale patterns were then superimposed on the nanoimprinted PDMS films by exposing them to ultraviolet radiation in oxygen (UVO) through a transmission electron microscopy grid mask having variable microscale patterning. UVO exposure leads to conversion and densification of PDMS to SiO , leading to micron height relief features that follow a linear scaling relation with pattern dimension. Further, the pattern scopes are shown to collapse into a master curve by normalized feature values. Interestingly, these relief structures preserve the nanoscale features. In this paper, the influence of the self-limiting PDMS densification, wall stress at the boundary of micro-depression, and UVO exposure energy is studied in control of the micro-depression scale. This simple two-step imprinting process involving both nanoimprinting and UV radiation allows for facile fabrication of the dimension adjustable micro-nano hierarchically structures not only on elastomer films but also on thermoplastic polymer films. Coarse-grained molecular dynamics simulations were performed to correlate the surface tension and elastic properties of polymeric materials to the deformation of the pattern structure.
通过结合纳米压印和微米级紫外臭氧（UVO）辐射，可以控制大面积聚合物薄膜的表面起伏结构，从而得到具有分级结构的表面。首先，通过用数字视频盘上的图案对弹性体[聚二甲基硅氧烷（PDMS）]薄膜进行纳米压印来形成纳米级图案。然后，通过具有可变微米级图案的透射电子显微镜网格掩膜，在氧气中对纳米压印的PDMS薄膜进行紫外辐射，从而将微米级图案叠加在纳米压印的PDMS薄膜上。UVO曝光会导致PDMS转化为SiO 并致密化，从而形成微米级高度起伏特征，这些特征与图案尺寸呈线性比例关系。此外，通过归一化特征值表明图案范围会汇聚成一条主曲线。有趣的是，这些起伏结构保留了纳米级特征。在本文中，研究了自限性PDMS致密化、微凹陷边界处的壁应力以及UVO曝光能量对微凹陷尺度控制的影响。这种简单的两步压印工艺，包括纳米压印和紫外线辐射，不仅可以在弹性体薄膜上，还可以在热塑性聚合物薄膜上轻松制造尺寸可调的微纳分级结构。进行了粗粒度分子动力学模拟，以将聚合物材料的表面张力和弹性特性与图案结构的变形联系起来。
