Liu Meifang, Zheng Yueqing, Liu Yiyang, Zhang Zhanwen, Wang Yuguang, Chen Qiang, Li Jing, Li Jie, Huang Yawen, Yin Qiang
Research Center of Laser Fusion, China Academy of Engineering Physics Mianyang 621900 China
Institute of Mechanical Manufacturing Technology, China Academy of Engineering Physics Mianyang 621900 China.
RSC Adv. 2019 Dec 17;9(71):41943-41954. doi: 10.1039/c9ra07141e. eCollection 2019 Dec 13.
Driven by the need to prepare monodisperse compound droplets, the formation mechanism of compound droplets was comprehensively investigated. With increasing poly(vinyl alcohol) (PVA) concentration in the W2 phase, the formation mechanism of inner W1 droplet is not affected while the behavior of the O phase in the W2 phase is different. The W1/O compound droplets can form stably in an inner squeezing - outer dripping regime, but the structure of the W1/O compound droplets are affected by the formation time matching between inner W1 droplet and W1/O compound droplets, which influences the stability of the compound droplets. Moreover, the formation process of the W1/O compound droplet is composed of cone recoiling, neck formation, neck developing, neck thinning and neck pinch-off. The formation time of the W1/O compound droplet is mainly determined the neck formation stage. The higher interfacial tension is unfavorable to the neck formation at the initial stages, but it makes the Laplace pressure difference increasing, which promotes the thinning of the neck in the neck pinch-off stage. The results provide more in-depth insights of the effects of surfactants on the formation of compound droplets, benefiting for preparing monodisperse and stable compound droplets.
受制备单分散复合液滴需求的驱动，对复合液滴的形成机制进行了全面研究。随着W2相中聚乙烯醇（PVA）浓度的增加，内部W1液滴的形成机制不受影响，而O相在W2相中的行为有所不同。W1/O复合液滴能在内部挤压-外部滴落模式下稳定形成，但W1/O复合液滴的结构受内部W1液滴与W1/O复合液滴形成时间匹配的影响，这会影响复合液滴的稳定性。此外，W1/O复合液滴的形成过程由圆锥回缩、颈部形成、颈部发展、颈部变细和颈部 pinch-off 组成。W1/O复合液滴的形成时间主要由颈部形成阶段决定。较高的界面张力在初始阶段不利于颈部形成，但会使拉普拉斯压差增大，这在颈部 pinch-off 阶段促进颈部变细。这些结果为表面活性剂对复合液滴形成的影响提供了更深入的见解，有利于制备单分散且稳定的复合液滴。
