Storage Studies of Langmuir−Blodgett (LB) Films of Methacrylate Copolymers Derivatized with Disperse Red-13

Abstract

Optical storage and photoisomerization characteristics were investigated for composite Langmuir−Blodgett (LB) films made up of methacrylate copolymers with different weight percentages of disperse red-13 and cadmium stearate. The influence of the dye content in the copolymer and number of layers of the composite LB films on the optical storage characteristics is discussed. Distance-dependent cooperative interactions between azobenzene chromophores seem to affect the time to achieve 50% of maximum birefringence and the amount of remaining birefringence after the writing beam is switched off. LB films were also characterized by UV−vis, FTIR, and XRD measurements. The LB fabrication followed a systematic investigation of monolayer properties of the dye-containing methacrylate copolymers using surface pressure and surface potential isotherms, to identify optimal deposition conditions. For instance, monolayers from pure copolymers were not amenable to transfer onto solid substrates, which was circumvented by codeposition with cadmium stearate.