Fabrication of silsesquioxane-based nano-wrinkled structures by coupling the polymeric surface onto rigid templates assembled from unique deca-silsesquioxane

Abstract

In this work, a facile strategy to fabricate double-layer nano-wrinkled structures by coupling the polymeric surface onto silsesquioxane rigid templates has been proposed. Aza-Michael addition was applied to construct the bulk layer by using octakis(aminophenyl) silsesquioxane (OAPS) and decakis(methacryloxypropyl) silsesquioxane (CMSQ-T₁₀). Subsequently, a top layer was fabricated through free-radical polymerization of octakis(methacryloxypropyl) silsesquioxane (CMSQ-T₈) and hexafluorobutyl acrylate (HFBA). For the first time, well defined nanoisland structures were achieved via reaction-induced assembly of two kinds of silsesquioxane cages in the rigid layer, which could further serve as an in situ template or a scaffold for top polymerization. As a result, the template role of the bulk layer and compressive stress caused by mismatch of different volumetric shrinkages of reactions between top and bulk layers led to the double-layer nano-wrinkled structures, which could be observed using a Field Emission Scanning Electron Microscope (FE-SEM) and an Atomic Force Microscope (AFM). Moreover, by tuning bilayer formulations, controllable nano-wrinkled structures can be obtained. The minimum reflectance of resulting nano-wrinkled surface is decreased to 3.51 ± 0.03% (maximum transmittance 98.51 ± 0.02%). Furthermore, the resulting surface shows obvious hydrophobicity and superior thermal stability, thus suggesting its potential use as antireflective surfaces in optical devices, solar cells and various optoelectronic devices.