Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision 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 (RCOCH=CHC6H5), where R = CH3, C2H5, n-C5H11, n-C11H23, t-C4H9, cyclo-C6H11, and C6H5. 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.
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