Microstructured surfaces injection molded from thermoplastic elastomers have emerging applications as superhydrobic surfaces and patterned adhesives, but there is a limited understanding of the factors affecting replication with these materials. This work investigates the interactions of the tooling aspect ratio and feature orientation (negative and positive tooling) and thermoplastic elastomer hard segment content on microfeature replication. Electroformed nickel tooling having positive and negative features with different geometries and aspect ratios of 0.02:1 to 2:1 were molded from three copolyester thermoplastic elastomers with similar chemistry and different hardness values. The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Results were correlated with elastomer properties.

The effects of microfeature spacing on the replication of thermoplastic elastomer features was investigated using micropillars with two diameters (10 μm and 20 μm) and three spacing ratios (0.5:1, 1:1, and 2:1). The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Filling simulations provided insight into the process. Feature spacing significantly affected the replication of micropillars using a thermoplastic elastomer. This replication was competition between pressurization, relaxation, and cooling of the melt. Higher pressures generally improved feature replication, but did not always create perfect replication. Relaxation of the highly aligned polymer chains and cooling effects restricted filling, tended to reduce feature height, and increase feature diameters. POLYM. ENG. SCI., 56:1330–1338, 2016. © 2016 Society of Plastics Engineers