Abstract
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.
Original language | English |
---|---|
Journal | Journal of Colloid and Interface Science |
Volume | 353 |
Issue number | 1 |
Pages (from-to) | 301-310 |
ISSN | 0021-9797 |
DOIs | |
Publication status | Published - 2011 |
Keywords
- Cyanosilane surface coating
- Capillary filling
- Nanofluidics
- Gouy–Chapman–Stern triple-layer model
- Silica nanochannels