Wettability modification of polydimethylsiloxane surface by fabricating micropillar and microhole arrays

Fabrication of microscale surface structures is a promising method for controlling the surface wettability of materials. Herein, the micropillar and microhole arrays of polydimethylsiloxane (PDMS) were fabricated through a soft lithography process, and the modified wettability was investigated. Using PDMS samples with different degrees of crosslinking, a PDMS-PDMS pattern transfer was achieved, and the microhole and micropillar arrays were obtained from a single master substrate. The surface geometries of the prepared PDMS samples were characterized via scanning electron microscopy and laser scanning microscopy. It was demonstrated that the PDMS micropillar and microhole arrays were effective in changing the contact angles of liquids with different surface tensions (water, ethylene glycol, olive oil, and hexadecane). The measured contact angles of the liquids on a PDMS micropillar array were quantitatively interpreted in both the wetting and repellent regimes based on the Cassie-Baxter model. (C) 2017 Elsevier B. V. All rights reserved.