Dual-Wavelength Photoinduced Reversible-Deactivation Radical Polymerization Directed by Monomer and Initiator Reactivity

Abstract

Combining multiple photocontrolled polymerization mechanisms within a single reaction enables the dynamic activation of distinct monomer classes, thereby streamlining the synthesis of unique polymer architectures and networks. Incorporating distinct photocontrolled polymerization methods mediated by active cations and radicals has been demonstrated to be effective. Yet, their integration into certain applications can be limited by the distinct, stringent reaction conditions required to avoid premature quenching (i.e., nucleophiles and oxygen). Here, we introduce a dual-wavelength, photoinduced reversible-deactivation radical polymerization (photo-RDRP) strategy that relies exclusively on radical species by combining photoiniferter reversible addition–fragmentation chain-transfer polymerization (PI-RAFT) and photoinduced atom transfer radical polymerization (photo-ATRP). Through the interplay of wavelength-specific activation and the inherent reactivity of a bifunctional macroiniferter, we demonstrate light-dependent incorporation of a range of more- and less-activated monomers via photo-ATRP and PI-RAFT polymerization. Radical reactivity of vinyl monomers and macroiniferter-derived reinitiating radicals are systematically investigated to direct monomer selectivity upon photoactivation using distinct light wavelengths. As a proof of concept, spatially defined polymer networks with distinct mechanical properties are printed using a single resin mixture via multicolor digital light processing.