Journal article
Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels
Theoretical Microfluidics Group, Theory Section, Department of Micro- and Nanotechnology, Technical University of Denmark1
Theory Section, Department of Micro- and Nanotechnology, Technical University of Denmark2
Department of Micro- and Nanotechnology, Technical University of Denmark3
University of California at San Diego4
We present a combined theoretical and experimental analysis of the solid–liquid interface of fused-silica nanofabricated channels with and without a hydrophilic 3-cyanopropyldimethylchlorosilane (cyanosilane) coating. We develop a model that relaxes the assumption that the surface parameters C1, C2, and pK+ are constant and independent of surface composition.
Our theoretical model consists of three parts: (i) a chemical equilibrium model of the bare or coated wall, (ii) a chemical equilibrium model of the buffered bulk electrolyte, and (iii) a self-consistent Gouy–Chapman–Stern triple-layer model of the electrochemical double layer coupling these two equilibrium models.
To validate our model, we used both pH-sensitive dye-based capillary filling experiments as well as electro-osmotic current-monitoring measurements. Using our model we predict the dependence of ζ potential, surface charge density, and capillary filling length ratio on ionic strength for different surface compositions, which can be difficult to achieve otherwise.
Language: | English |
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Year: | 2011 |
Pages: | 301-310 |
ISSN: | 10957103 and 00219797 |
Types: | Journal article |
DOI: | 10.1016/j.jcis.2010.09.025 |
ORCIDs: | Bruus, Henrik |