Aono Kodai, Ueno Kazuyuki, Hamasaki Sho, Sakurai Yuri, Yusa Shin-Ichi, Nakamura Yoshinobu, Fujii Syuji
Division of Applied Chemistry, Environmental and Biomedical Engineering, Graduate School of Engineering, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka 535-8585, Japan.
Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
Langmuir. 2022 Jun 21;38(24):7603-7610. doi: 10.1021/acs.langmuir.2c00869. Epub 2022 Jun 6.
There has been increasing interest in colloidal particles adsorbed at the air-water interface, which lead to stabilization of aqueous foams and liquid marbles. The wettability of the particles at the interface is known to play an important role in determining the type of air/water dispersed system. Foams are preferably formed using relatively hydrophilic particles, and liquid marbles tend to be formed using relatively hydrophobic particles. In this study, submicrometer-sized polystyrene particles carrying poly(,-diethylaminoethyl methacrylate) hairs (PDEA-PS particles), which are synthesized by dispersion polymerization, are demonstrated to work as a particulate stabilizer for both aqueous foams and liquid marbles. A key point for the hydrophilic PDEA-PS particles to stabilize both aqueous foams and liquid marbles, which have been generally stabilized with hydrophilic and hydrophobic particles, respectively, is the wetting mode of the particles with respect to water. The flocculates of PDEA-PS particles adsorb to the air-water interface from the aqueous phase to stabilize foam in a Wenzel mode, and the dried PDEA-PS particles adsorb to the interface as aggregates from the air phase to stabilize liquid marbles in a metastable Cassie-Baxter mode. On the basis of the difference in the wetting mode, stabilization of an air-in-water-in-air multiple gas-liquid dispersed system, named "foam marble", is realized. After the evaporation of water from the foam marble, a porous sphere is successfully obtained with pore sizes of a few tens of micrometers (reflecting the bubble sizes) and a few tens of nanometers (reflecting the gap sizes among the PDEA-PS particles).
人们对吸附在空气 - 水界面的胶体颗粒越来越感兴趣，这些颗粒可使水性泡沫和液体弹珠稳定。已知颗粒在界面处的润湿性在决定空气/水分散体系的类型中起着重要作用。泡沫优选使用相对亲水的颗粒形成，而液体弹珠倾向于使用相对疏水的颗粒形成。在本研究中，通过分散聚合合成的带有聚（甲基丙烯酸 - 二乙氨基乙酯）链的亚微米级聚苯乙烯颗粒（PDEA - PS颗粒）被证明可作为水性泡沫和液体弹珠的颗粒稳定剂。亲水的PDEA - PS颗粒能够稳定通常分别由亲水和疏水颗粒稳定的水性泡沫和液体弹珠的关键点在于颗粒相对于水的润湿模式。PDEA - PS颗粒的絮凝物从水相吸附到空气 - 水界面，以文泽尔模式稳定泡沫，而干燥的PDEA - PS颗粒作为聚集体从气相吸附到界面，以亚稳态的卡西 - 巴克斯特模式稳定液体弹珠。基于润湿模式的差异，实现了一种名为“泡沫弹珠”的空气 - 水 - 空气多重气 - 液分散体系的稳定化。在泡沫弹珠中的水蒸发后，成功获得了孔径为几十微米（反映气泡尺寸）和几十纳米（反映PDEA - PS颗粒之间的间隙尺寸）的多孔球体。
