Real-Time Determination of Ultraviolet Degradation Kinetics of Polymers in Solution

Abstract

Real time monitoring of ultraviolet degradation of polystyrene with varying degrees of methylvinyl ketone (MVK) substitutions was carried out. This automated technique is demonstrated to be rapid, accurate and quantitative, yielding the absolute degradation rate constant in terms of number of bonds broken per second per initial g/mol of polymer mass. The MVK substituted heteropolymers yielded degradation rates around two orders of magnitude higher than pure polystyrene, which varied linearly with the percentage of MVK substitution. By the use of an actinometric determination of absorbed flux in the sample, approximate degradation quantum efficiencies of 0.00169, 0.0965, 0.159 and 0.194 were obtained for pure polystyrene and the 5, 10 and 15% MVK substituted copolymers, respectively.