Ultrafast dynamics of proflavine bound to poly (methacrylic acid) in aqueous solution

•The dynamics of PMAA labeled with proflavine cation have been explored by steady-state and time-resolved fluorescence.•The shorter decay time of 15ps represents the reorientation dynamics of the water molecules.•The increase in the decay time on increasing the pH from 2.0 to 5.0 is due to the slow reorientation of water.•The hydrophobic part of the polyelectrolyte restricts the solvent reorganization during the solvation at low pH.