Liquid Marbles Prepared from pH-Responsive Sterically Stabilized Latex Particles
详细信息 查看全文
- 作者：Syuji Fujii ; Motomichi Suzaki ; Steven P. Armes ; Damien Dupin ; Sho Hamasaki ; Kodai Aono ; Yoshinobu Nakamura
- 刊名：Langmuir
- 出版年：2011
- 出版时间：July 5, 2011
- 年：2011
- 卷：27
- 期：13
- 页码：8067-8074
- 全文大小：938K
- 年卷期：v.27,no.13(July 5, 2011)
- ISSN：1520-5827
文摘
Submicrometer-sized pH-responsive sterically stabilized polystyrene (PS) latex particles were synthesized by dispersion polymerization in isopropyl alcohol with a poly[2-(diethylamino)ethyl methacrylate]- (PDEA-) based macroinitiator. These PDEA鈥揚S latexes were extensively characterized with respect to their particle size distribution, morphology, chemical composition, and pH-responsive behavior. Millimeter- and centimeter-sized 鈥渓iquid marbles鈥?with aqueous volumes varying between 15 渭L and 2.0 mL were readily prepared by rolling water droplets on the dried PDEA鈥揚S latex powder. The larger liquid marbles adopted nonspherical shapes due to gravitational forces; analysis of this deformation enabled the surface tension to be estimated. Scanning electron microscopy and fluorescence microscopy studies indicated that flocs of the PDEA鈥揚S particles were adsorbed at the surface of these water droplets, leading to stable liquid marbles. The relative mechanical integrity of the liquid marbles prepared from alkaline aqueous solution (pH 10) was higher than those prepared from acidic aqueous solution (pH 2) as judged by droplet roller experiments. These liquid marbles exhibited long-term stability (over 1 h) when transferred onto the surface of liquid water, provided that the solution pH of the subphase was above pH 8. In contrast, the use of acidic solutions led to immediate disintegration of these liquid marbles within 10 min, with dispersal of the PDEA鈥揚S latex particles in the aqueous solution. Thus the critical minimum solution pH required for long-term liquid marble stability correlates closely with the known pKa value of 7.3 for the PDEA stabilizer chains. Stable liquid marbles were also successfully prepared from aqueous Gellan gum solution and glycerol.