Photophysical behavior of pyrene molecules in polymer nano-sheets

This study describes the photophysical behavior of the pyrene chromophore, which was incorporated into polymer nanosheets by Langmuir-Blodgett (LB) technique, from the viewpoint of molecular motion and molecular orientations in the nano-structured films. The pyrene orientation was strongly affected by the side alkyl chains of the polymers. Fluorescence behavior of the pyrene chromophore placed in polymer LB films was studied by steady-state fluorescence spectroscopy and time-resolved fluorescence spectroscopy. Molecular motion of the pyrene chromophore was highly restricted in both LB films, so the excimer intensity in LB film became smaller than that in THF solution and its maximum wavelength showed blue shift. Moreover, capping layers onto the nanosheet affected the fluorescence behavior of pyrene molecule in p(tPA/PyMA), in which the pyrene was exposed to the surface. It is concluded that the orientation and the environment of the pyrene chromophore were changed by the capping layers.