Polymer brushes are a key technology for engineering functional surfaces, with applications in biomedicine including biosensing, cell culture, regenerative medicine, and antibacterial coatings. Structuring polymer brushes offers powerful opportunities to tailor interfacial properties for specific applications; however, complex fabrication and patterning processes often limit their broader use. Here, we report a subtractive photopatterning strategy that decouples brush fabrication from surface structuring.
Using radical ring-opening polymerization of cyclic monomers containing photocleavable cyclobutane units, photodegradable targets are directly embedded into the polymer brush main chains. After initial fabrication, the brushes can be selectively degraded by light, triggering photocleavage of the cyclobutane units. This enables continuous, controllable brush degradation of more than 50% of the original brush height for topographical patterning, without affecting key surface properties such as hydrophilicity and adhesion forces. The inherent photodegradability of the brushes eliminates the need for additional chemicals or catalysts and allows patterning using only light and water at ambient temperature.