Synthesis of fluorescent polymers from hydrostyryl pyridinium derivatives and their multichromatic fluorescence behaviors

To synthesize fluorescent polymers, hydrostyryl pyridinium derivatives were methacrylated and afforded monomers of MA-SP-OH-X (X = NO2, F, substituted group on phenyl ring) followed by free-radically homo- and copolymerized with methyl methacrylate (MMA), butyl acrylate (BA) and styrene (St), respectively. The resulting copolymers showed green, orange and red emissions with significant multichromatic behaviors and solvent- and excitation-dependence. Moreover, P(BA-co-MA-SP-OH-NO2) behaved as a thermal elastomer and showed high stretchability and self-heal performance. In addition, with the copolymers as macro-additives, fluorescent poly(vinylidene difluoride) (PVDF) films were fabricated by using electrospinning technique. The unexpected multichromatic fluorescent behaviors showed by the copolymers were attributed to the enol-to-keto transition of phenol group in SP-OH moiety and significant aggregation of fluorophore moieties.