Phenylvinilbisquinolines as fluorescent markers in functionalized polypropylene films

In this work, polypropylene films (PP) and maleic anhydride graft polypropylene (PPgMA) at different concentrations of a photoluminescent dye 2,2′-(1,4-phenylenedivinylene) bisquinoline (M1) were prepared by solvent casting. The fluorescence spectrum of M1-dye showed a maximum peak at 424 nm in xylene which corresponds to the blue region of the electromagnetic spectrum. In the PP films, new peaks at 505 and 535 nm appeared that can be ascribed to interchain species formed by intermolecular π-π stacking and likely hydrogen-bonding interaction as found for other quinaldine oligomers. By thermal annealing of the film heating at 130 °C during 60 min, it was possible to overcome these interactions. The results show that thermal annealing of films is able to disrupt M1-aggregates as a consequence of macromolecular reorganization promoted by heating. The emission responses detected in PP/PPgMA/M1 films are associated with a small-dispersed M1-aggregates associated with a polar character between maleic anhydride and M1. The fluorescence changes of M1 in the polymer films indicate the possibility of using this bisquinoline-dye as an optical sensor for detecting structural modification of thermoplastic polymers.