Photosensitization of Bioinspired Thymine Containing Polymers

D. REYNA; D. M. MARTINO

Colorado School of Mines, Golden

Otro; 6th Annual Summer School on Green Chemistry; 2008

Styrene-based biopolymers containing ionic and thymine groups chemically attached to the polystyrene structure were experimentally investigated. The ionic groups make the polymer water-soluble, eliminating the environmental and health concerns associated with the use of volatile organic solvents, a routine in conventional photoresist processes. In addition, when these biopolymers undergo UV light irradiation a photocyclization reaction between adjacent thymines takes place, rendering them water-insoluble. The material obtained is refereed to as photoresist. Vinylbenzyl thymine (VBT) was copolymerized in a batch solution process with vinylbenzyltriethylammonium chloride (VBA). The reactions were carried out at 65C in a batch-stirred tank reactor using 2,2’-azobisisobutyronitrile (AIBN) as initiator. Samples were taken along the reactions to determine the monomer conversion, solubility, chemical composition, and molecular weight distribution. The obtained copolymers were cured using UV irradiation (270nm) and using visible light (520nm) with the aid of Eosin Y as sensitizer. The effects of irradiation dose, sensitizer concentration, molecular structure and chemical composition of the polymer on the curing process were investigated. The cured material was characterized by means of Fourier Transform Infra Red (FTIR) and UV-Vis Spectroscopy.