One‐Pot, Self‐Initiated Polymerization Approach to Functional Poly(4‐Vinylpyridine)s

This study aims to develop a novel one‐pot, self‐initiated method for the synthesis of quaternized poly(4‐vinylpyridine)s (QPVPs) with pendant‐reactive Zincke salt structures. This approach involves quaternization‐induced polymerization of 4‐vinylpyridine (4VP) using 1‐halo‐2,4‐dinitrobenzenes (X‐DNP; X = Cl, Br) to form poly(4‐vinyl(2,4‐dinitrophenyl)pyridinium halide)s (PVP1‐X‐DNP). The proposed mechanism involves halo‐anion‐induced polymerization initiated by a nucleophilic attack on the quaternized 4VP intermediate. The resulting polymers are further modified via substitution reactions with primary amines, enabling the introduction of various substituents. Structural characterization by NMR and IR spectroscopy confirmed successful polymer formation and postmodification. UV–vis and NMR measurements indicated that PVP1‐Cl − ‐DNP formed a charge transfer (CT) complex with an electron‐rich compound, whereas photoluminescence (PL) measurements revealed that the polymer exhibited fluorescence quenching behavior. A morphological analysis using SEM demonstrated the formation of spherical structures in the cast films. This is the first report of a self‐initiated polymerization route for producing reactive QPVPs, offering a simple and versatile method for synthesizing functional polymers without external initiators.