基于无机盐诱导的可控聚集制备纳米多孔结构减反射涂膜

Nanoporous antireflection coating prepared by controlled aggregation based on inorganic salt induction

纳米多孔膜是一种重要的减反射膜,目前制备方法存在步骤繁琐、条件苛刻以及效率低等不足,如何简便、高效地制备减反射性能优良的纳米多孔涂膜具有很大的挑战性。文章提出以无机盐可控地诱导成膜过程中乳胶粒聚集,一步制备纳米多孔结构减反射涂膜的设想。在以胶乳制备多孔结构减反射时,分别考察了氯化铵(NH4Cl,酸式盐)、氯化钠(NaCl,中性盐)和碳酸氢铵(NH4HCO3,碱式盐)为致孔剂时,涂膜的结构及减反射性能。研究表明:为达到实验的目的,与NH4Cl和NaCl相比,NH4HCO3更适宜作为纳米多孔膜的致孔剂;胶乳中加入NH4HCO3后,乳液分散稳定性提高;被涂覆于基材表面后,乳液中NH4HCO3的浓度随着水分的蒸发不断增高,引起乳胶粒子聚集、堆积形成多孔结构;之后,在100℃干燥涂膜时,NH4HCO3又可通过热分解而被去除;以NH4HCO3为致孔剂时,涂膜具有纳米多孔结构,对入射光散射小,单面涂膜玻璃增透率提高3.6%,增透效率明显高于采用NaCl或NH4Cl所制的涂膜。

Nano porous membrane is a very important anti reflective coating. At present, its preparation method involves tedious steps, rigorous conditions and low efficiency, etc. How to prepare nano porous coating with excellent antireflection performance is very challenging. Inthis paper, the idea of using inorganic salts to induce the aggregation of latex particles in the process of coating formation and preparing nano porous anti reflective coating in one step is proposed. During preparing nano porous anti reflective coating with latex, the structure and antireflection performance of the coating were investigated when acid salt （ammonium chloride, NH4Cl）, neutral salt （sodium chloride, NaCl） and basic salt （ammonium bicarbonate, NH4HCO3） were used as the porogen. It is found that basic salt （ammonium bicarbonate, NH4HCO3） is the ideal porogen, compared with NH4Cl and NaCl. After NH4HCO3 was added in the latex, dispersion stability of the emulsion improved. After it was coated on the substrate surface, the concentration of NH4HCO3 in the emulsion continued to rise with the moisture evaporation, thus leading to the aggregation of latex particles to form porous structure. In addition, when the coating was dried at 100℃, NH4HCO3 could be removed by thermal decomposition. And when NH4HCO3 is used as the porogen, the coating has nano porous structure and little incident light scattering. The transmittance of one side coated glass increases by 3.6%, obviously higher than that of coatings prepared with NaCl or NH4Cl.