Adsorption Behavior of Low-Concentration Imidazolium-Based

Ionic Liquid Surfactant on Silica Nanoparticles

Liu Yan,* Longjiao Qiao, Yinping Xiang, and Rong Guo*

School of Chemistry and Chemical Engineering, Yangzhou University

Abstract:The adsorption behavior of imidazolium-based ionic liquid surfactant ([C₁₂mim]Br) on silica nanoparticles (NPs) has been studied with turbidity, isothermal titration microcalorimetry, fluorescence spectroscopy, and dynamic light scattering (DLS) measurements. Both the electrostatic attraction and the hydrogen bonding interaction between silica NP and [C₁₂mim]Br play crucial roles during [C₁₂mim]Br monomers binding to silica NPs at low surfactant concentration, and the hydrophobic effect leads to formation of micelle-like aggregates on silica NP surfaces with the further increase of surfactant concentration. Furthermore, it is found that sodium halide salts favor the adsorption of [C₁₂mim]Br on silica NP surfaces by decreasing the electrostatic repulsions. Anions with more hydrophobicity and the ability to form hydrogen bonding have more pronounced effect. Compared with DTAB, [C₁₂mim]Br has much stronger binding ability with silica NPs at pH 7.0. More interestingly, [C₁₂mim]Br can still form micelle-like aggregates on silica NP surfaces, but DTAB cannot at pH 2.0. The hydrogen bonding between the imidazolium ring and silica NPs is the principal contributor to these observations. Our results will contribute to the elucidation of silica NP/cationic surfactant interaction from molecular scale and the widely applications of silica NP/surfactant systems in practice.

langmuir, 2016, 32, 2582–2590.

文章链接:http://pubs.acs.org/doi/abs/10.1021/acs.langmuir.6b00302

Langmuir-2016-32-2582