Photolyzable Polymer Brushes: Subtractive 3D Structuring of Surfaces Using Water and Light.

Polymer brushes are a key technology for designing surfaces, with applications in biomedicine alone including biosensing, cell culture, regenerative medicine, and antibacterial coatings. The structuring of polymer brushes has the potential to precisely tailor interfaces for specific application requirements. However, complex fabrication processes can limit the applications of polymer brushes. Herein, a subtractive patterning process is reported, which decouples initial fabrication from the structuring process. Using radical ring-opening polymerization of cyclic monomers with photocleavable cyclobutane rings, photodegradable targets are directly embedded into the polymer brush main chains. After the initial fabrication, these brushes can be readily degraded with light, triggering photocleavage of the cyclobutane units. This enables continuous brush degradation of over 50% of brush height for topographical patterning without affecting brush properties such as hydrophilicity and adhesion force. The inherent photodegradability of the polymer brush eliminates the need for additional chemicals or catalysts and can be carried out using nothing but water and light at ambient temperature.