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

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 (NH 4 HCO 3 ). 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 NH 4 HCO 3 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 NH 4 HCO 3 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 NH 4 HCO 3 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.