Sham Alison Y W, Notley Shannon M
Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Acton 2601, ACT, Australia.
Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Acton 2601, ACT, Australia.
J Colloid Interface Sci. 2016 May 1;469:196-204. doi: 10.1016/j.jcis.2016.02.015. Epub 2016 Feb 4.
Liquid-air foams have been stabilised using a suspension of graphene particles at very low particle loadings. The suspension was prepared through the liquid phase exfoliation of graphite in the presence of the non-ionic tri-block surfactant, Pluronic® F108. The graphene particles possess an extremely high aspect ratio, with lateral dimensions of between 0.1 and 1.3 μm as evidenced by TEM imaging. The particles were shown to exhibit a number of other properties known to favour stabilisation of foam structures. Particle surface activity was confirmed through surface tension measurements, suggesting the particles favour adsorption at the air-water interface. The evolution of bubble size distributions over time indicated the presence of particles yielded improvements to foam stability due to a reduction in disproportionation. Foam stability measurements showed a non-linear relationship between foam half-life and graphene concentration, indicative of the rate at which particles adsorb at bubble surfaces. The wettability of the graphene particles was altered upon addition of alkali metal chlorides, with the stability of the foams being enhanced according to the series Na(+)>Li(+)>K(+)>Cs(+). This effect is indicative of the relative hydration capacity of each salt with respect to the surfactant, which is adsorbed along the graphene plane as a result of the exfoliation process. Thus, surfactant exfoliated graphene particles exhibit a number of different features that demonstrate efficient application of high-aspect ratio particles in the customisation and enhancement of foams.
在极低的颗粒负载量下，使用石墨烯颗粒悬浮液可使液 - 气泡沫得到稳定。该悬浮液是通过在非离子三嵌段表面活性剂Pluronic® F108存在下对石墨进行液相剥离制备的。石墨烯颗粒具有极高的纵横比，透射电子显微镜成像显示其横向尺寸在0.1至1.3μm之间。已证明这些颗粒具有许多其他有利于泡沫结构稳定的特性。通过表面张力测量证实了颗粒的表面活性，这表明颗粒有利于在气 - 水界面吸附。随着时间推移气泡尺寸分布的演变表明，颗粒的存在由于歧化作用的减少而提高了泡沫稳定性。泡沫稳定性测量表明泡沫半衰期与石墨烯浓度之间存在非线性关系，这表明颗粒在气泡表面吸附的速率。添加碱金属氯化物后，石墨烯颗粒的润湿性发生改变，泡沫的稳定性根据Na(+)>Li(+)>K(+)>Cs(+)的顺序增强。这种效应表明每种盐相对于表面活性剂的相对水合能力，表面活性剂由于剥离过程而沿石墨烯平面吸附。因此，表面活性剂剥离的石墨烯颗粒表现出许多不同的特性，证明了高纵横比颗粒在泡沫定制和增强方面的有效应用。
