Meniscus motion

FIG. 2 Calibration of a thin quartz capillary by measuring rates of meniscus motion v in dependence on applied pressure difference AP. The length of water column in the capillary was equal to / = 9.28 cm (curve 1) and 5.28 cm (curve 2) t = 19°C. 

The values of K for the second stage of imbibition (when / > /q) increase with Co due to an inerease in absolute value of Cm. However, an increase in K values (from 3 x 10 to 1.7 x 10 cm/s ) is limited because the rate of meniscus motion influences the Cm values in the opposite direction (Fig. 16). 

The rate of meniscus motion follows diffusion kinetics (see Section III.B) with coefficients of surface diffusion 10 " to 10 cm /s. To the end, the... 

This results in formation of both oil-in-water and water-in-oil emulsions depending on the direction of meniscus motion. 

It seems that two parameters are essential to benefit from these assembly mechanisms. Obviously, the control of the substrate velocity is needed to control the meniscus motion and to perform the assembly over large areas. In the two processes investigated, it has been shown also that controlling the hydrod3mamic flows created by evaporation is critical and can easily be achieved by adjusting the substrate temperature. In convective assembly, the temperature allows fast and accurate control of the deposition speed, including reversal of the assembly process, whereas in capillary assembly, a distinct temperature threshold has been found that triggered the assembly. 

Localized deposition near the meniscus during meniscus motion has been reported for general colloidal particles and for SWCNTs." In those studies particles deposit chiefly at the meniscus, where drying effects increase their local concentration (see chapter 15 for a detailed description of this process). Here, kinetics data shows that deposition increases with time and that there is negligible deposition for very small incubation times. This latter fact indicates that in our case no significant deposition occurs at the meniscus. Furthermore, on examining areas on the substrate where the drop had a total residence time of less than five seconds. 

L. Li, Y. Kazoe, K. Mawatari, Y. Sugii, T. Kitamori, Viscosity and wetting property of water confined in extended nanospace simultaneously measured from highly-pressurized meniscus motion. J. Phys. Chem. Lett. 3(17), 2447-2452 (2012)... 

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