期刊
JOURNAL OF COLLOID AND INTERFACE SCIENCE
卷 611, 期 -, 页码 670-683出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2021.12.113
关键词
Contact angle; Nanoparticles; Liquid surface/interface; Immersion depth; Zeta (electrokinetic) potential; Electrophoretic mobility; Sessile drop; Atomic force microscopy; Streaming current; X-ray reflectivity
资金
- research grant Verbundforschung [BMBF/05KS7FK3/05KS10FK2]
- Verbundforschung [BMBF/05K16FK1/05K19FK2, 05K19K2]
- DFG (Deutsche Forschungsgemeinschaft) [278836263]
- DFG Graduate School Processes in natural and technical Particle Fluid-Systems (PintPFS) [GRK2462, 390794421]
- DFG within the Collaborative Research Initiative Tailor-Made Multi-Scale Materials Systems [192346071, SFB 986]
Experimental study on the wetting properties of nanoparticles at different interfaces found that the receding contact angle on smooth surfaces provides a good estimate of nanoparticle wetting properties, while macroscopic contact angles alone cannot predict adsorption barriers that prevent nanoparticles from segregating to the interface.
Hypothesis: We test whether the wettability of nanoparticles (NPs) straddling at an air/water surface or oil/water interface can be extrapolated from sessile drop-derived macroscopic contact angles (mCAs) on planar substrates, assuming that both the nanoparticles and the macroscopic substrates are chemically equivalent and feature the same electrokinetic potential. Experiments: Pure silica (SiO2) and amino-terminated silica (APTES-SiO2) NPs are compared to macroscopic surfaces with extremely low roughness (root mean square [RMS] roughness <= 2 nm) or a roughness determined by a close-packed layer of NPs (RMS roughness similar to 35 nm). Equivalence of the surface chemistry is assessed by comparing the electrokinetic potentials of the NPs via electrophoretic light scattering and of the macroscopic substrates via streaming current analysis. The wettability of the macroscopic substrates is obtained from advancing (ACAS) and receding contact angles (RCAs) and in situ synchrotron X-ray reflectivity (XRR) provided by the NP wettability at the liquid interfaces. Findings: Generally, the RCA on smooth surfaces provides a good estimate of NP wetting properties. However, mCAs alone cannot predict adsorption barriers that prevent NP segregation to the interface, as is the case with the pure SiO2 nanoparticles. This strategy greatly facilitates assessing the wetting properties of NPs for applications such as emulsion formulation, flotation, or water remediation. (C) 2021 Elsevier Inc. All rights reserved.
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