School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States.
Langmuir. 2011 Aug 16;27(16):10000-6. doi: 10.1021/la202176u. Epub 2011 Jul 21.
The interaction between energetically asymmetric hydrophilic and hydrophobic surfaces has fundamental and practical importance in both industrial and natural colloidal systems. The interaction forces between a hydrophilic silica sphere and a silanated, hydrophobic glass plate in N-methyl-2-pyrrolidone (NMP)-water binary mixtures were measured using atomic force microscopy (AFM). A strong and long-range attractive force was observed in pure water and was attributed to the formation of capillary bridges associated with nanoscale bubbles initially present on the hydrophobic surface. When NMP was added, the capillary force and corresponding pull-off force became less attractive, which was explained readily in terms of the surface wettability by the binary solvent mixture. Similar to the case of symmetric (two hydrophilic) surfaces, the range of attraction between the asymmetric surfaces was maximized at around 30 vol % NMP, which is consistent with the formation of a thick adsorbed macrocluster layer on the hydrophilic silica surface.
亲水性和疏水性不对称表面之间的相互作用在工业和自然胶体系统中都具有重要的基础和实际意义。使用原子力显微镜（AFM）测量了 N-甲基-2-吡咯烷酮（NMP）-水二元混合物中亲水性二氧化硅球和硅烷化疏水性玻璃片之间的相互作用力。在纯水中观察到强且长程的吸引力，这归因于与疏水面初始存在的纳米级气泡相关联的毛细桥的形成。当添加 NMP 时，毛细力和相应的拔出力的吸引力变得不那么强，这很容易用二元溶剂混合物对表面润湿性来解释。类似于对称（两个亲水）表面的情况，不对称表面之间的吸引力范围在大约 30 体积% NMP 时达到最大值，这与亲水二氧化硅表面上形成厚吸附宏观团簇层一致。
