Flexible nanoporous antireflection coatings prepared from controllable latex aggregation and their efficient color deepening function

Abstract

Anti-reflection coating (ARC) materials are of great fundamental scientific importance but suffer from many problems, such as cumbersome and time-consuming fabrication processes, poor durability, and use of organic solvents. Herein, the preparation of ARCs is realized through a facile evaporation process of a latex blend containing crosslinked polymethyl methacrylate (cPMMA), non-crosslinked polybutyl acrylate (PBA) and ammonium bicarbonate (NH4HCO3). The cPMMA particles act as building blocks for constructing the porous coating skeleton, the PBA particles work as binders to ensure the durable structural flexibility, and NH4HCO3 is used to trigger the aggregation of the particles during latex drying and control the porous structure. This novel method is straightforward, easy to operate and cost-effective, and NH4HCO3 can be removed through thermal decomposition at temperatures no more than 100 °C, thus avoiding the use of any solvents. Moreover, the refractive indices and the thicknesses of the coatings can be modulated by the concentration of NH4HCO3 and the particle fraction of the coating dispersions, respectively. These characteristics allow the coatings with low transmittance loss of less than 0.5% as transmitted peaks spanning from 440 to 750 nm. When applied to flexible substrates, including colored flat sheets and black silk fabric, the light penetrating into the substance is promoted and selectively absorbed by the colorants, leading to a significant increase in the color depth. Finally, the coating exhibited excellent durability with extremely low transmittance drop of 0.3% even after 20 cycles of 180° bending and relaxation of the coated sheet.