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Photodegradable polymers. II. Preparation of styrene copolymers with alkyl and phenyl β‐styryl ketones and their photodegradability
Author(s) -
Shiraishi Shinsaku,
Senō Manabu,
Ishii Masao,
Asahara Teruzo
Publication year - 1976
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1976.070200912
Subject(s) - copolymer , styrene , quantum yield , photodegradation , photochemistry , alkyl , polymer chemistry , bond cleavage , benzene , chemistry , polymer , ketone , gel permeation chromatography , quenching (fluorescence) , materials science , fluorescence , organic chemistry , catalysis , photocatalysis , physics , quantum mechanics
Photodegradable polymers having pendent carbonyl groups attached directly to the polymer chain were prepared by copolymerization of styrene (St) with alkyl and phenyl β‐styryl ketones (RCOCHCHC 6 H 5 ), where R = CH 3 , C 2 H 5 , n ‐C 5 H 11 , n ‐C 11 H 23 , t ‐C 4 H 9 , cyclo‐C 6 H 11 , and C 6 H 5 . The photodegradability of these copolymers was traced by viscometric and IR spectroscopic measurements. The degradability of St–benzalacetophenone (BAPh) copolymer is greater than that of St–alkyl styryl ketone copolymers under the irradiation of a high‐pressure Hg lamp. The photodecomposition behavior St–BAPh copolymer was investigated in detail by a spectoirradiation technique. The changes in molecular weight and its distribution by photodegradation were measured by gel permeation chromatography, and the quantum yield for bond scission along the main chains of the copolymer was estimated to be about 5 × 10 −3 by 328 nm irradiation in a benzene solution. Examination of the effect of wavelength of the radiation on the bond scission showed that 328‐nm light is most effective. The photochemical degradation process was shown to occur chiefly via triplet state of carbonyl groups by the quenching technique using 1,3‐cyclohexadiene as a triplet quencher. The quantum yield of decarbonylation process was also estimated to be about 4.2 × 10 −2 in benzene.