Photodegradation of polyacetaldehyde in solution. I. Direct photolysis

Abstract The quantum yields measured for the random scission of main‐chain bonds of polyacetaldehyde in benzene solution by 254 nm irradiation at 298°K are on the order of 10−3–10−4 scissions per quantum absorbed by the polymer. The quantum yields are unaffected by oxygen but are dependent upon initial polymer concentration and upon the inverse square root of absorbed light intensity. The direct photochemistry involves excitation of carbonyl chromophores in their 1nπ* bands, and a Norrish type I process is believed to be responsible for subsequent free‐radical random‐chain scissions. It has been established that direct photoexcitation processes do not lead to sequential depolymerization of polyacetaldehyde to monomer.