Micropatterning of confined surfaces with polymer brushes by two-photon-initiated reversible addition–fragmentation chain-transfer polymerization

Abstract

Photopatterned polymer brushes provide a viable option to alter the surface properties of biosensors, substrates for tissue engineering, or microelectronic implants. Although the one-photon direct laser writing enables excellent control over pattern geometry, it has an inherently limited writing resolution caused by the used light source; moreover, no patterning of undercuts or channels is possible. This article describes the preparation of patterned polymer brushes on confined glass substrates using two-photon-initiated reversible addition-fragmentation chain-transfer (2PRAFT) polymerization of N-acryloylmorpholine as a hydrophilic model monomer. The polymer brushes prepared by 2PRAFT exhibit a height of 10 nm, as confirmed by atomic force microscopy. In addition, well-defined printed structures down to 5 μm size are prepared, which outperforms the currently achieved resolution of polymer brushes prepared by one-photon direct laser writing.