PDMS double casting method enabled by plasma treatment and alcohol passivation

Abstract

We propose a simple and efficient polydimethylsiloxane (PDMS)double casting method using plasma treatment followed by methanol or ethanol treatment. The plasma treatment oxidizes the functional groups on the surface of the PDMS mold, showing an increase in the concentration of hydroxyl functional groups (OH); subsequent exposure to the alcohols prevents adherence of the second PDMS casting. This process effectively passivates the surface of the PDMS master mold to suppress further chemical bonding. This two-step surface treatment ensures excellent double casting performance at a single micron scale resolution to yield micron level reproduction of objects featuring high aspect ratios, two-dimensional surface micropatterns, and complex three-dimensional microstructures. © 2019 Elsevier B.V.