摘要
系统地研究了亚微米聚苯乙烯微球在气-液界面的组装机理.聚苯乙烯微球在介质对流的带动下会到达悬浮液的表面并在气-液界面组装,气-液界面处聚苯乙烯微球间由弯液面产生的毛细管力是组装的推动力.界面处聚苯乙烯微球在干燥过程中其润湿性发生了转变,由完全润湿到部分润湿并最终变成不润湿,相应的聚苯乙烯微球与分散介质间接触角也逐渐增大.研究表明,只有接触角达到或超过某数值θ′critical时,才能够出现气-液界面组装现象.考虑到PS胶粒晶体的表面是“规则”粗糙的表面,由Wenzel公式知θ′critical大于测量值θ=22°.聚苯乙烯微球润湿性的转变是界面组装发生和持续进行的关键性因素.
The mechanism of polystyrene submicrosphere assembly in aqueous suspension was studied systemically. During the evaporation of solvent, the PS spheres were transported to the water-air surface, where these spheres self-assembled into colloidal crystal through the capillary force between the particles at water-air interface. The wettability of the PS spheres at the water-air interface could change from complete wetting to partial wetting and finally to non-wetting with the evaporation of water, so that the contact angle between the PS spheres and water increased gradually. The researches showed that only after the contact angle reached a critical value θ＇critical, could the PS sphere-assembly occur. The critical value θ＇critical which was obtained from the Wenzel equation, was greate than the measured value 8critical θcritical =22°, coarse. The change of the PS spheres at water-air interface from assembling into colloidal crystals. because the surface of PS colloidal crystal was ＂regularly＂ hydrophilic to hydrophobic is essential for the PS spheres
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第5期3017-3021,共5页
Acta Physica Sinica
基金
国家重点基础研究发展规划项目(批准号:2004CB217808)
国家自然科学基金(批准号:20376046
20473108)资助的课题~~
关键词
自组装
胶粒晶体
聚苯乙烯微球
润湿性
self-assembly, colloidal crystals, polystyrene microspheres, wettability
