Impact of cationic surfactant on fluorescent complex of pyrene labeled poly(acrylic acid) and methylene blue

Abstract

Attractive smart and emissive nanomaterials are designed by embedding the methylene blue (MB) in the complex of pyrene labeled poly(acrylic acid) (PAA25Py3) and dodecyltrimethylammonium chloride (C12TAC) using the supramolecular host-guest strategy. The investigation methods were surface tension, UV–vis, steady-state fluorescence, electrokinetic potential, dynamic light scattering and microscopy. A comparative study about the adsorption at air/water interface of anionic polymer and oppositely charged surfactant complexes without (PS) and with MB (PS/MB) was made. The photophysical properties of PS and PS/MB assemblies were highlighted by both pyrene (Py) and MB. The self-aggregation and conformation of polymer with MB in the PS matrix were analyzed. At low surfactant concentration, small and well dispersed PS/MB complexes form hydrophobic environments as detected by Py label. The PS complexes quenched the MB emission. At high surfactant amounts, the Py label signaled an unusual micropolarity. Thus, the formation of iceberg-like environments due to the cation-л interactions in large aggregates of PS complexes was proved by polarity index. In these high polar and rigide nanoenvironments of PS aggregates, the dye fluorescence is enhanced. The obtained results have the potential applications in chemical sensing and imaging.