A Physical Approach To Specifically Improve the Mobility of Alkane Liquid Drops

Abstract

Seamless control of resistance to liquid drop movement for polar (water) and nonpolar alkane (n-hexadecane, n-dodecane, and n-decane) probe liquids on substrate surfaces was successfully demonstrated using molten linear poly(dimethylsiloxane) (PDMS) brush films with a range of different molecular weights (MWs). The ease of movement of liquid drops critically depended on polymer chain mobility as it relates to both polymer MW and solvent swelling on these chemically- and topographically identical surfaces. Our brush films therefore displayed lower resistances to liquid drop movement with decreasing polymer MW and surface tension of probe liquid as measured by contact angle (CA) hysteresis and tilt angle measurements. Subsequently, while mobility of water drops was inferior and became worse at higher MWs, n-decane drops were found to experience little resistance to movement on these polymer brush films. Calculating CA hysteresis as Δθ(cos) = cos θ(R) - cos θ(A) (θ(A) and θ(R) are the advancing and receding CAs, respectively) rather than the standard Δθ = θ(A) - θ(R) was found to be advantageous for estimation of the actual dynamic dewetting behavior of various probe liquids on an inclined substrate.

Superhydrophobic Photosensitizers. Mechanistic Studies of 1O2 Generation in the Plastron and Solid/Liquid Droplet Interface

“…30,31 All droplets, regardless of size, easily rolled off the PDMS surfaces upon tilting the surfaces, as would be expected of a superhydrophobic surface with low contact angle hysteresis (facile rolling due to the small number of liquid/solid contact points). 32,33 It is this high mobility of the droplet that enables the facile removal of the drop from the surface and its subsequent analysis by UV-vis spectroscopy.…”

Temperature‐Driven Switching of Water Adhesion on Organogel Surface

“…Different from a traditional surface with low water adhesion, where the contact angle (CA) is usually larger than 150°, the CA on organogel at T > T m surface is 85°, revealing the typical slippery state with low CA and ultralow CAH. [ 15 ] Notably, we chose PDMS here as the crosslinked network to produce organogel for demonstration. In fact, the current method is also valid for other kinds of crosslinked polymers.…”

Applicability of Cassie–Baxter equation for superhydrophobic fluoropolymer–silica composite films

“…When silica content was more than 0.2 wt.%, TMS 14 sample which has the lowest Zonyl-TM content, showed larger deviations from the theory. In the case of samples with higher Zonyl-TM contents (TMS 29 and TMS 48 ), deviations from the theory was high when silica content was larger than 0.3 wt.%. However, when silica content was lower (<0.1 wt.%), experimental and theoretical contact angle values were close to each other and thus the deviations from the theory was low.…”

“…In practical systems, measurement of only static CA (Â e ) is not enough to explain polymer surface characteristics, so advancing (Â a ), receding (Â r ) CAs and the contact angle hysteresis (CAH) are required to accurately characterize the dewetting properties of the surfaces [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. CAH can be caused due to surface roughness [1,18,33,34], chemical heterogeneity [1,18,[35][36][37], drop size effect [1,18,38,39], molecular reorientation [33], and the penetration of the liquid molecules into the solid surface [1,18,40].…”