Microstructure of silica particle monolayer films formed by capillary immersion force
Microstructure of silica particle monolayer films formed by capillary immersion force
复制标题
DOI：
10.1023/a:1024427810668
复制
发表时间：
2003-04-01
影响因子：
2.5
通讯作者：
Yamaguchi, Y
中科院分区：
文献类型：
--
作者：
Okubo, T;Chujo, S;Yamaguchi, Y
我们研究了蒸发诱导自组装法制备的二氧化硅颗粒单层膜的微观结构上的颗粒间排斥和颗粒-基底相互作用的影响作为表面覆盖度的函数。在固定条件下蒸发通过棒涂流延在PET基底上的单分散胶态二氧化硅颗粒（直径106 nm）的悬浮液，得到二维颗粒膜。颗粒间的排斥力由颗粒悬浮液的zeta电位控制。通过氩气射频等离子体对基底进行表面处理，改变了颗粒与基底的相互作用。用原子力显微镜（AFM）观察了自组装微结构，并通过Voronoi分析定量评价了颗粒有序性和畴质量。在所有尝试的条件下，显微组织随着表面覆盖率（phi（c））的增加而改善。然而，在phi（c）达到约0.6之前，观察到由于实验条件导致的phi（c）和微观结构之间的相关性的小差异，其中颗粒有序性和畴质量都更具有颗粒间排斥性只有当颗粒-基质间吸引力较小的基质中，（没有表面处理的基材）。这些结果与原子力显微镜观察结果一致。通过考虑该过程的可行模型，可以推断，微结构对颗粒间排斥的依赖性源自于在临界值phi（c）（= 49/75，在模型中近似于0.65）处颗粒间碰撞频率的跳跃。我们发现，较强的颗粒间排斥和较弱的颗粒-基底吸引力对于高于约0.6的临界phi（c）的较好的微结构是优选的。
We have investigated the effect of inter-particle repulsion and particle - substrate interaction on the microstructure of silica particle monolayer films fabricated by an evaporation-induced self-assembly method as a function of surface coverage. Suspensions of mono-dispersed colloidal silica particles (106 nm diameter) without binders cast on PET substrates by bar coating were evaporated under a fixed condition to give two-dimensional particle films. The interparticle repulsion was controlled by zeta potential of the particle suspensions. The particle - substrate interaction was varied by the surface treatment of the substrates by argon radio frequency plasma. The self-assembled microstructure was observed by atomic force microscopy (AFM) and quantitatively evaluated by Voronoi analysis in terms of particle order and domain quality. In all the conditions attempted, the microstructure improved with the increase of surface coverage (phi(c)). However, little difference in the correlation between phi(c) and the microstructure due to the experimental conditions was observed until phi(c) reached about 0.6, where both particle order and domain quality of more inter-particle repulsion ( higher absolute value of zeta potential) began to exceed those of less inter-particle repulsion only when the substrates with less particle - substrate attraction ( substrates with no surface treatment) were used. These results were consistent with the AFM observation. By considering a feasible model for the process, it could be inferred that the microstructure dependence on the inter-particle repulsion originated from a leap in the frequency of inter-particle collision at a critical value of phi(c) (= 49/75 approximate to 0.65 in the model). We found that stronger inter-particle repulsion and weaker particle - substrate attraction were preferable for the better microstructure above the critical phi(c) of about 0.6.