Photolysis of poly-acyl styrene polymers

Abstract

The following is a study of the long wave (wavelength >300 nm) photolysis of a series of poly acyl styrenes, in particular, poly-p-acetyl-styrene (PPAS), polyp- propionyl-styrene (PPPS), poly-o-acetyl-styrene (POAS), poly-o-proponylstyrene (POPS). All photoreactions are initiated from the carbonyl triplet. It is seen that in the solid state, below Tg the main photoprocesses that take place in all systems are Norrish I cleavage and photoreduction. In addition, the ortho polymers have the proper structure to allow for photoenolization. Gas product analysis of these ortho polymers, in the solid state below Tg suggest evidence for ground state control. Transient spectroscopy does indicate the presence of enol formation in these ortho polymers. Viscosity studies on solutions showed that secondary reactions with these polymers include competitive cross linking and chain scission. There is a definite solvent effect observed for all of these systems and the solvent quality has an effect on the balance of these secondary reactions. A detailed explanation of this solvent effect is discussed.