RUI: Phase Stability and Chromophore Reorientation in Photorefractive Polymer Composites

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This RUI project addresses photo-refractive macromolecular materials research with emphasis on the synthesis and characterization of new chromophores with appropriate non-linear optical response, and seeks to identify the relationship between phase stability and chromophore reorientation in low-Tg (glass transition temperature) photorefractive polymers. Photorefractive polymers blended with nonlinear optical dye molecules exhibit relatively large refractive index modulations due to spatial reorientation of the dye. An interdisciplinary team of Drew University students and faculty from the Chemistry and Physics departments will fabricate photorefractive polymers spanning a range of materials behavior by synthesizing dye molecules of relatively similar optical properties but considerably different interactions with the host polymer. The phase stability of each composite will be observed through measurements of the time dependent optical absorption coefficient. The refractive index modulation will be determined by diffraction efficiency measurements, and the relative orientational mobility of the dyes will be inferred through frequency dependent transmission ellipsometry. This data will be used to delineate boundaries of the phase-stability/orientational-mobility tradeoff, and to improve understanding of dye-polymer interactions and the design of blends suitable for applications.%%% An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. All of the materials fabrication and optical characterization will occur at Drew University in chemistry and laser laboratories. These laboratories have been developed in part through an NSF-ILI grant "Materials science and nonlinear optics in physics and chemistry laboratories" and represent an ongoing effort to integrate the fabrication and characterization of nonlinear optical materials with Drew undergraduate instructional labs. The experiments are tabletop in scale and expose students to the photonic and electronic technology valued by employers and graduate schools. Students will also have the opportunity to study the holographic image storage properties of the materials they fabricate through a collaboration between the principal investigator and Dr. G. Wood of the Army Research Lab. The research is intellectually accessible to undergraduates, giving them a sense of ownership in their work. This RUI award will support six summer research students over three years, and will provide equipment support for Honors and Independent Study projects during the academic year. Results will be disseminated in peer-reviewed research literature with student co-authors and presented at professional meetings. ***