ERC, Inc., Space & Missile Propulsion Division, Air Force Research Laboratory, Edwards AFB, California 93524, United States.
Langmuir. 2011 Aug 16;27(16):10206-15. doi: 10.1021/la201545a. Epub 2011 Jul 19.
Fluoroalkyl-functionalized silica particles for use in nonwetting surfaces were prepared by treatment of silica particles with fluoroalkyl-functional chlorosilanes. Both fumed and precipitated silica were studied, as well as the efficiency of surface coverage using mono-, di-, and trifunctional chlorosilanes. The most effective surface treatment was accomplished via the surface grafting of monofunctional chlorosilanes in the presence of preadsorbed dimethylamine under anhydrous conditions at room temperature. Confirmation of covalent attachment was accomplished via Fourier transform infrared (FT-IR) spectroscopy, while elemental analysis, thermogravimetric analysis, and nitrogen adsorption isotherms were used to determine grafting densities and additional key geometric characteristics of the grafted layer. The effect of residual silanol content on the moisture uptake properties of the modified silica particles was determined by measuring the water uptake of unbound particles, while liquid wetting properties were determined by dynamic contact angle analysis of elastomeric composites. Although residual silanol content was shown to effect wetting properties, results suggest that surface geometry dominates the performance of liquid-repellent surfaces. The potential use of fluoroalkyl-functionalized silica particles for hydrophobic and oleophobic applications is discussed.
用于非润湿表面的氟烷基功能化硅颗粒是通过用氟烷基功能化氯硅烷处理硅颗粒制备的。研究了烟炱硅石和沉淀硅石，以及使用单官能、双官能和三官能氯硅烷进行表面覆盖的效率。在无水条件下，室温下，在预吸附的二甲胺存在下，通过单官能氯硅烷的表面接枝，最有效地进行了表面处理。通过傅里叶变换红外（FT-IR）光谱证实了共价键的附着，而元素分析、热重分析和氮气吸附等温线用于确定接枝密度和接枝层的其他关键几何特征。通过测量未结合颗粒的吸水率来确定残留硅醇含量对改性硅颗粒吸湿性的影响，而通过弹性体复合材料的动态接触角分析来确定液体润湿性能。尽管残留硅醇含量对润湿性能有影响，但结果表明表面几何形状主导着液体排斥表面的性能。讨论了氟烷基功能化硅颗粒在疏油和疏油应用中的潜在用途。
