Li Xiangmeng, Wang Chunhui, Shao Jinyou, Ding Yucheng, Tian Hongmiao, Li Xiangming, Wang Li
Micro- and Nanotechnology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , Xi'an, Shaanxi 710049, China.
ACS Appl Mater Interfaces. 2014 Nov 26;6(22):20300-8. doi: 10.1021/am505835z. Epub 2014 Nov 7.
In this paper we present an economical process to create anisotropic microtextures based on periodic parallel stripes of monolayer silica nanoparticles (NPs) patterned by geometrically confined evaporative self-assembly (GCESA). In the GCESA process, a straight meniscus of a colloidal dispersion is initially formed in an opened enclosure, which is composed of two parallel plates bounded by a U-shaped spacer sidewall on three sides with an evaporating outlet on the fourth side. Lateral evaporation of the colloidal dispersion leads to periodic "stick-slip" receding of the meniscus (evaporative front), as triggered by the "coffee-ring" effect, promoting the assembly of silica NPs into periodic parallel stripes. The morphology of stripes can be well controlled by tailoring process variables such as substrate wettability, NP concentration, temperature, and gap height, etc. Furthermore, arrayed patterns of nanopillars or nanoholes are generated on a silicon wafer using the as-prepared colloidal stripes as an etching mask or template. Such arrayed patterns can reveal unique anisotropic wetting properties, which have a large contact angle hysteresis viewing from both the parallel and perpendicular directions in addition to a large wetting anisotropy.
在本文中，我们展示了一种经济的方法，该方法基于通过几何限制蒸发自组装（GCESA）形成的单层二氧化硅纳米颗粒（NP）的周期性平行条纹来创建各向异性微纹理。在GCESA过程中，胶体分散体的直弯月面最初在一个开放的容器中形成，该容器由两个平行板组成，在三个侧面由U形间隔侧壁界定，在第四侧面有一个蒸发出口。胶体分散体的横向蒸发导致弯月面（蒸发前沿）周期性的“粘滑”后退，这是由“咖啡环”效应触发的，促进了二氧化硅NP组装成周期性平行条纹。通过调整诸如基底润湿性、NP浓度、温度和间隙高度等工艺变量，可以很好地控制条纹的形态。此外，使用制备好的胶体条纹作为蚀刻掩膜或模板，在硅片上生成纳米柱或纳米孔的阵列图案。这种阵列图案可以展现出独特的各向异性润湿特性，除了具有大的润湿各向异性外，从平行和垂直方向观察都具有大的接触角滞后。
