AI 中文总结
该研究通过介尺度模拟揭示了干燥悬垂液滴聚并及蒸发对各向异性粒子取向的影响，推导了几何标度，明确接触角调控取向保持效果，为印刷材料性能调控提供了依据。
AI 中文摘要
各向异性粒子的取向强烈决定印刷材料的功能特性，但多数研究聚焦于单个蒸发液滴内的粒子取向。然而在基于液滴的印刷中，相邻液滴可发生聚并，产生快速毛细流，该流会重新分布物质并显著影响最终形貌。本文采用介尺度模拟研究液滴聚并及后续蒸发如何共同决定不同接触角和体积的悬垂液滴中粒子的取向与再分布。聚并早期，对液滴接触角与体积不对称性的所有组合，沿聚并方向的平均向列序均增加；后期平均向列序或持续增加或下降，取决于液滴几何。我们推导了基于曲率和体积不对称性的几何标度，证明模拟结果可归为一条主曲线，确定了一个有效几何不对称参数，该参数控制聚并结束时的平均向列序。蒸发期间，接触角强烈影响聚并诱导的取向结构向最终沉积层的转移：小接触角下接触线钉扎时间更长，能更好地保持取向；反之，大接触角促进接触线运动，使平均向列序降低，削弱取向，同时在最终沉积层中产生更强的浓度梯度。
英文摘要
Alignment of anisotropic particles strongly governs the functional properties of printed materials, yet most studies have focused on particle alignment in single evaporating droplets. In droplet- based printing, however, neighboring droplets can coalesce, generating rapid capillary flows that redistribute material and markedly affect the final morphology. Here, we use mesoscale simulations to investigate how droplet coalescence and subsequent evaporation jointly determine alignment and redistribution in sessile droplets with different contact angles and volumes. During the early stages of coalescence, the mean nematic order along the coalescence direction increases for all combinations of contact-angle and volume asymmetries of the droplets. At later times, the mean nematic order either continues to increase or decreases, depending on the droplet geometry. We derive a geometric scaling based on curvature and volume asymmetry and show that the simulation results collapse onto a master curve, identifying an effective geometric asymmetry parameter that governs the mean nematic order at the end of coalescence. During evaporation, the contact angle strongly influences how the coalescence-induced orientational structure is transferred to the final deposit. For small contact angles, the contact line remains pinned for a longer duration, better preserving alignment. In contrast, larger contact angles promote contact-line motion, which weakens alignment, as reflected by a reduced mean nematic order, while simultaneously generating stronger concentration gradients in the final deposit.
Comments15 pages,6 figures
