Patterning of RAFT Polymer Networks by Laser Deactivation

Abstract Reversible addition‐fragmentation chain‐transfer (RAFT) polymer networks grow in interest due to their living and tunable characteristics. An essential step toward exploiting these characteristics is the production of precise patterns for growth. Herein, a novel, straightforward strategy to produce patterns to control growth on RAFT‐based living polymer networks (LPNs) is presented. A 405 nm laser is used to degrade the RAFT agents in selected regions, generating a pattern. This occurs through homolytic photocleavage at the C─S bond, leading to the typical RAFT equilibrium state with the R‐group radical and a thiyl radical species, followed by irreversible loss of CS2 to produce a Z‐group derived thiol. Using this technique, both “on/off” patterns and more detailed greyscale patterns are produced using images of varying complexity. Post production growth then shows that these patterns are visually retained after iniferter growth with a fluorescent monomer. Due to the deactivation of selected RAFT agents, the authors are able to perform discriminate growth with network‐wide irradiation. This selective degradation technique serves as an alternative technique for producing patterns on RAFT LPNs