Antireflection coating on silk fabric fabricated from reactive silica nanoparticles and its deepening color performance

Abstract

In this study, we reported the functionalization of raw silica nanoparticles (SiNPs) with (2-ethyl hydrogen sulfate) sulfonyl (EHSS) groups and their utility as a building block to produce a washing durable antireflection coating on silk fabric. The raw SiNPs were synthesized via classical Stober method and subsequently reacted with (3-methacryloxypropyl) trimethoxysilane, allowing for the raw particle surfaces to be left with ethoxy and methoxy groups. Then, EHSS groups were immobilized onto the SiNP surfaces through the reactions with EHSS group-terminated silane coupling agents. The EHSS functionalization was confirmed by Fourier transform infrared spectroscopy and elemental analysis. These EHSS group-functionalized SiNPs were applied onto silk fabrics by following a dip-coating technique under mild conditions. During this process, the ethoxy and methoxy groups were involved in the condensation reactions to give a cross-linked silica coating that was covalently attached onto the fiber surface through the reactions between EHSS groups and silk fibers. The coating was demonstrated to have a nano-porous microstructure and provided fibers with nano-roughened surfaces, which showed high efficiency in antireflection and increasing light transmission. Since the transmitted light would be selectively absorbed by the dyestuff, the coating applied onto colored silk fabrics gave rise to a more than 30 % increase of the color strength without changing the original hues of the fabrics. Furthermore, being sharply different from the common darkening resins consisting of polysiloxanes and fluorochemicals, the silica coating brought darkening effects without compromising the inherent hydrophilicity of silk fabrics.