Effect of softness of polydimethylsiloxane on the hydrophobicity of pillar-like patterned surfaces
Journal
Soft Matter
Journal Volume
8
Journal Issue
4
Pages
1079-1086
Date Issued
2012
Date
2012
Author(s)
Abstract
In this study, we have demonstrated that different wetting behavior of regular pillar-like patterned PDMS can be achieved by controlling the mixing ratio of polydimethylsiloxane's (PDMS's) prepolymer base and curing agent. The dynamic contact angles and sliding angles of water droplet on these patterned surfaces are carefully measured. It is found that the experimental results for PDMS substrates prepared at the mixing ratio of base to curing agent 10:1 are consistent with the theoretical predictions of the Wenzel model and Cassie model. However, for the PDMS substrates prepared at the mixing ratio of base to curing agent 20:1, the wetting behavior would change due to the deformation of the structure - collapse of pillars due to the softness. In addition, the dynamic phenomenon of the impregnating process of water penetrating into the pillars is observed through the optical microscope when a water droplet is placed on the regular pillar-like patterned PDMS substrates prepared at the mixing ratio of base to curing agent 20:1. The pillars are pushed down by water flow one after another like dominoes. The flow pattern of the impregnating process is discussed. © 2012 The Royal Society of Chemistry.
SDGs
Other Subjects
Curing agents; Dynamic contact angle; Dynamic phenomena; Mixing ratios; Optical microscopes; Patterned surface; PDMS substrate; Prepolymers; Sliding angle; Theoretical prediction; Water droplets; Water flows; Wetting behavior; Behavioral research; Contact angle; Curing; Drops; Microchannels; Mixing; Wetting; Silicones; Leucaena leucocephala
Type
journal article
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