Self-reporting fluorescent step-growth RAFT polymers based on nitrile imine-mediated tetrazole-ene cycloaddition chemistry

We introduce an inherently fluorescent self-reporting step-growth polymer system as well as a fluorescence-based methodology for accessing the kinetics of the underpinning photoinduced nitrile imine-mediated tetra-zole-ene cycloaddition (NITEC) process, using an equimolar mixture of a bismaleimide linker and a bifunctional alpha,omega- tetrazole-chain transfer agent (CTA).Similarly, alpha,omega-tetrazole-capped polystyrene, prepared via RAFT polymerization, was employed as a photoreactive macromonomer. Upon UV irradiation, the tetrazole moiety readily reacts with activated dialkenes producing the fluorescent pyrazoline-containing polymer. Thus, the fluorescence emission of the step-growth polymers is directly correlated with the number of ligation points in the polymer, forming an ideal self-reporting sensor system. The Viability of the fluorescence-based quantification is verified via NMR spectroscopy, evidencing that fluorescence-based polymerization monitoring is a viable avenue in cases where NMR spectroscopy is difficult to conduct