Photodegradation behavior of tert‐butyl vinyl ketone polymers and copolymers with styrene and α‐methylstyrene

Photodegradation behavior of atactic and isotactic polymers of tert‐butyl vinyl ketone (t‐BVK) and its copolymers with styrene and α‐methylstyrene was studied in dioxane as a solvent at room temperature. The quantum yield of main‐chain scission of atactic poly(t‐BVK) was found to be larger than that of isotactic poly(t‐BVK) and atactic poly(methyl vinyl ketone). From the Stern‐Volmer plots on the quenching study of atactic poly(t‐BVK) with naphthalene and 2,5‐dimethyl‐2,4‐hexadiene, it was found that 60–70% of its photochemical reaction underwent main‐chain scission from the triplet state. It was also found that the increase in t‐BVK contents of both copolymers accelerated the photodegradation, and the copolymer with styrene was more photodegradable than that with α‐methylstyrene. These results seemed to suggest that the main‐chain scission of these vinyl ketone polymers and copolymers proceeded through a Norrish type II photoelimination mechanism.