INVESTIGATIONS TOWARDS THE PREPARATION OF PHOTORESPONSIVE POLYMERS BASED ON PHOTOCLEAVABLE TELLURIUM-CONTAINING CROSS-LINKS

Abstract

<p>The goal of this research project is to synthesize, characterize, and examine the properties of a material that undergoes a decrease in refractive index upon exposure to light. It is anticipated that such photoresponses could elicit previously unknown nonlinear phenomena including self-trapped black beams. An appropriate material for these investigations would be a polymer cross-linked by photocleavable groups causing a Δ<em>n</em> < 0. Organo-ditellurides, molecules that contain a Te-Te bond, would be appropriate for the crosslinks as their σ*_Te-Te ← n_Te transition usually absorbs light between 400 and 500 nm, and can lead to photodissociation of the chalcogen-chalcogen bond.</p> <p>Initial attempts to directly functionalize a polymer (polystyrene) resulted in intractable solids. A more promising approach relies on the preparation of cross-linking agents followed by co-polymerization. Despite literature claims, to date, there is no structurally authenticated photoresponsive molecule that simultaneously contains vinyl (CH=CH) and telluride (-Te-) functional groups. The work in this thesis has yielded what would be the first example, in addition to a crystal structure obtained by X-ray diffraction, the compound has been characterized by multinuclear NMR (¹H, ¹³C, ¹²⁵Te) and vibrational spectroscopy with the support of DFT calculations.</p>