Patterning and modification of PDMS surface through laser micromachining of silicon masters and molding

Abstract

We describe preparation of micro patterned PDMS sample surfaces and their chemical modification for the purposes of increased hydrophobicity. The process includes ablation of micrometer sized patterns on a silicon master by pulsed radiation from a Nd:YAG laser, transfer of the patterns to PDMS through molding, and chemical modification of the topmost surface layers of the polymer sample by further laser irradiation and UV/ozone treatment. The samples were characterized by XPS, FTIR, contact angle measurements, optical microscopy and SEM. The study shows the feasibility of the method to manufacture regular patterns with micron-sized cylindrical pillars and to control surface composition. In the absence of chemical modification of the surfaces due to preparation, we compare the effect of increased roughness on the contact angle with theoretically predicted values. Samples with patterned and chemically modified surfaces due to UV/ozone treatment show reduced hydrophobicity.