Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Langmuir. 2012 Sep 18;28(37):13496-502. doi: 10.1021/la3024887. Epub 2012 Sep 6.
A novel "sink and etch" technique is used to generate stable surface nanoporosity in poly(methyl methacrylate). Layer-by-layer assembly is first used to conformally coat PMMA substrates with a uniform layer of silica nanoparticles. Thermal annealing is then applied to cause sinking and engulfment of the silica nanoparticles into the thermoplastic PMMA surface. By selectively etching away the layer of embedded silica nanoparticles, a conformal porous layer of inversely templated structure can be obtained in the PMMA surface. Characterization with atomic force microscopy shows that a variety of nanoporous surface morphologies can be achieved simply by controlling the duration and temperature of thermal annealing. The nanoporous surfaces consisting of either as assembled silica nanoparticles or templated inverse porosity in PMMA were compared in terms of their antireflective (AR) properties. Measuring AR properties provided a quantitative means to compare the stability of these porous AR surfaces before and after several cleaning cycles. Our results show that while both types of surface porosity can provide excellent AR properties (optimized for 300-400 nm), the porous layer generated by the "sink and etch" technique showed superior mechanical stability.
一种新颖的“沉蚀”技术被用于在聚甲基丙烯酸甲酯（PMMA）中产生稳定的表面纳米多孔性。首先采用层层自组装技术，在 PMMA 基底上涂覆一层均匀的二氧化硅纳米颗粒。然后进行热退火，使二氧化硅纳米颗粒沉入并嵌入热塑性 PMMA 表面。通过选择性地刻蚀掉嵌入的二氧化硅纳米颗粒层，可以在 PMMA 表面获得具有反转模板结构的共形多孔层。原子力显微镜的表征表明，通过控制热退火的时间和温度，可以简单地实现各种纳米多孔表面形貌。对由组装的二氧化硅纳米颗粒或 PMMA 中的模板反转孔隙组成的纳米多孔表面进行了比较，以评估它们的抗反射（AR）性能。测量 AR 性能为比较这些多孔 AR 表面在几次清洗循环前后的稳定性提供了一种定量方法。研究结果表明，尽管两种类型的表面孔隙都可以提供优异的 AR 性能（针对 300-400nm 进行了优化），但“沉蚀”技术产生的多孔层具有更好的机械稳定性。
