Micropatterning of Confined Surfaces with Polymer Brushes by Two‐Photon‐Initiated Reversible Addition–Fragmentation Chain‐Transfer Polymerization

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.