Li Xuan, Feng Dong, Chen Lei, Weng Ding, Chen Chaolang, Wang Jiadao
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, PR China.
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, PR China.
J Colloid Interface Sci. 2021 May;589:187-197. doi: 10.1016/j.jcis.2020.12.079. Epub 2020 Dec 25.
A binary mixture was used during injection with one water-miscible component and the other water-immiscible, which can help particles to migrate toward and then self-assemble at the interface.
The ethanol-tetrachloromethane binary mixture was used to verify the self-assembly method, with the diameter of droplets being about 1 mm. As the ethanol diffused into the colloidal solution, the colloidal particles efficiently moved towards and self-assembled on the oil/water interface, while a colloidal particle film with high-coverage was able to rapidly form on the droplet surface even in an ultra-low concentration colloidal solution. The effects of ethanol concentration and particle concentration on self-assembly were investigated.
The driving force for self-assembly originated from the tension gradient generated by ethanol's concentration gradient at the particle/liquid interfaces, where the concentrations of ethanol and the colloidal solution had significant effects on self-assembly. The simulation and calculations results aligned well with experiments, providing the theoretical basis for this self-assembly method. Further, as-prepared magnetic particle-coated droplets transformed into a non-wetting soft solid, which had long lifetimes and could be precisely moved, coalesced, and transferred in various two-dimensional and three-dimensional liquid environments. Thus, wider applications are facilitated, such as droplet transfer, microreactor and other potential fields.
在注射过程中使用了一种二元混合物，其中一种成分与水混溶，另一种与水不混溶，这有助于颗粒向界面迁移并在界面处自组装。
使用乙醇 - 四氯化碳二元混合物来验证自组装方法，液滴直径约为1毫米。随着乙醇扩散到胶体溶液中，胶体颗粒有效地向油/水界面移动并在其上自组装，即使在超低浓度的胶体溶液中，高覆盖率的胶体颗粒膜也能够在液滴表面迅速形成。研究了乙醇浓度和颗粒浓度对自组装的影响。
自组装的驱动力源于乙醇在颗粒/液体界面处的浓度梯度产生的张力梯度，其中乙醇和胶体溶液的浓度对自组装有显著影响。模拟和计算结果与实验结果吻合良好，为这种自组装方法提供了理论依据。此外，制备的磁性颗粒包覆液滴转变为非润湿性软固体，具有长寿命，并且可以在各种二维和三维液体环境中精确移动、合并和转移。因此，便于更广泛的应用，如液滴转移、微反应器和其他潜在领域。
