Spectroscopic study of the interaction between methyl viologen and core–shell-structured polymer nanoparticles

Interaction between core–shell-structured PS-P4VP nanoparticles and methyl viologen (MV) adsorbed on the nanoparticle surface was studied by laser photolysis and steady-state spectroscopic methods. Fluorescence of MV was quenched by the addition of polymer nanoparticles, indicating an energy transfer between the adsorbed MV and the nanoparticles. When the polymer nanoparticles were added to the MV solution, two absorption bands with peaks of 390 nm and 330 nm were observed, corresponding to the MV^˙+ free in solution and that bound to the nanoparticle surface. The MV^˙+ free in solution moves rapidly to the nanoparticle surface and then is transformed into the bound state. The second-order decay rate constant of the adsorbed MV^˙+ is (2.4±0.2) × 10³ M⁻¹s⁻¹, being about a factor 22 slower than that in the bulk solution.