Photoreorientation of non isomerizing diphenyldiacetylene chromophores in polyelectrolyte complex Langmuir–Blodgett films

For investigations on the photoreorientation process we synthesized the amphiphile 6-(4-(4-(4-hexylphenyl)butadyne)phenoxy)hexanoic acid (DPDA) containing diphenyldiacetylene as chromophore. The amphiphile forms monolayers which are stabilized by complexation with poly(ethyleneimine) PEI present in the subphase. The DPDA/PEI complex monolayers were characterized at the air/water interface by recording the isotherms, by Brewster angle microscopy (BAM), and by UV/Vis spectroscopy. UV/Vis spectroscopy and BAM indicate a well ordered structure in the monolayer. The monolayers of the DPDA/PEI complex can be deposited onto hydrophobic substrates as Y-Type Langmuir–Blodgett (LB) films. The monolayer structure is retained in the LB film. The LB film shows optical anisotropy. Upon irradiation with polarized light, a photoreorientation process can be observed.