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亲水玻璃基片在掩模板的保护下,通过喷涂超疏水层,得到了被疏水层包围的圆形亲水区域.胶体液滴在这一区域被很好地限制,并且液滴体积可以在较大范围内变化,体积的变化可以改变液滴与基片的表观接触角.通过显微观察手段原位观察了表观接触角为疏水的受限胶体液滴蒸发过程中粒子沉积行为.在整个蒸发过程中,受限液滴边界被钉扎在亲疏水交界处.粒子沉积过程中,驱动粒子的液滴内部流动会发生变化.粒子沉积图案形成过程由三种流体行为控制,最初,Marangoni效应占主导作用,驱动粒子在液滴表面聚集,随之沉积到液滴边缘;随着蒸发进行,当接触角变小(<60°)时,由于边界蒸发速度更快导致的毛细补偿流使得粒子直接向边界沉积.在干燥的最后阶段,亲水区域内的液层变得很薄,只有一单层粒子存在于这一薄液层中,蒸发继续进行时,薄液层发生失稳使得粒子迅速聚集而形成网络化图案,由于粒子间距变小,球间的液桥毛细力也会参与到这一聚集过程中.
Under the protection of the mask, the hydrophilic glass substrate is sprayed with a superhydrophobic layer, resulting in a circular hydrophilic region surrounded by a hydrophobic layer.The colloidal droplets are well confined in this region and the droplet volume can be in the range of The change of the volume can change the apparent contact angle between the droplet and the substrate.The particle deposition behavior of the constrained colloidal droplet with apparent contact angle is observed by microscopic observation in situ. During the entire evaporation process, the boundary of the limited droplets is pinned at the junction of hydrophilic and hydrophobic. During the deposition of particles, the internal flow of the droplets driving the particles will change.The particle deposition pattern formation process is controlled by the three fluid behaviors, The Marangoni effect dominates and drives the particles to accumulate on the droplet surface and subsequently to the edge of the droplet. As the evaporation proceeds, the capillary compensatory flow due to faster evaporation at the boundary becomes smaller as the contact angle becomes smaller (<60 °) So that the particles directly deposited to the boundary in the final stage of drying, the liquid layer in the hydrophilic region becomes very thin, only a single layer of particles in this thin layer, the evaporation continues, the thin layer instability Make particles fast Pattern formed by aggregation network, since the inter-particle distance is reduced, the capillary force of the liquid bridge between the ball will participate in this aggregation process.