Abstract:

In this paper, the evaporation modes of nanodroplet on rough substrates are studied by molecular dynamics method, and the influence of ratio of contact area (RCA) between the nanodroplets and the rough interfaces on the contact radius and contact angle during the evaporation process of nanodroplets is discussed. The roughness of the interfaces is achieved by textured patterns based on the Wenzel wetting model. The results show that, in equilibrium, compared with the ideal smooth substrate, when the contact area ratio is smaller, the contact angle of the nanodroplet increases significantly (RCA = 33.3%, θ = 106°), while when the roughness of the substrates is larger, this phenomenon is not obvious (RCA = 50%, θ = 81°; RCA = 66.6%, θ = 85°). In the evaporation process, when RCA = 33.3%, the evaporation mode of nanodroplet is mixed mode, when RCA = 50%, the evaporation mode of nanodroplet is constant contact radius mode (CCR mode), and when RCA = 66.6%, the evaporation mode of nanodroplet is constant contact angle mode (CCA mode).

Key words: molecular dynamics, droplet, interface, ratio of contact area, evaporation

摘要：

通过采用分子动力学的方法对粗糙界面上纳米液滴的蒸发模式进行了研究，探讨了纳米液滴与粗糙界面的接触面积比（RCA）对纳米液滴蒸发过程中接触半径、接触角的影响。界面的粗糙度通过基于Wenzel润湿模型构建的纹理图案实现。研究表明，在平衡态时，相较于理想光滑界面，当接触面积比较小时，纳米液滴接触角增大明显（RCA = 33.3%，θ = 106°），而当接触面积比较大时，此现象不明显（RCA = 50%，θ = 81°；RCA = 66.6%，θ = 85°）。在蒸发过程中，当RCA = 33.3%时，纳米液滴的蒸发模式为混合模式（mixed mode）；当RCA = 50%时，纳米液滴的蒸发模式为恒定接触半径模式（CCR mode）；当RCA = 66.6%时，纳米液滴的蒸发模式为恒定接触角模式（CCA mode）。

关键词: 分子动力学, 液滴, 界面, 接触面积比, 蒸发