FORMATION OF ALDEHYDE GROUPS DURING THE PHOTOLYSIS OF POLY(METHYL METHACRYLATE)

Upon u.v. irradiation at lambda(inc) = 253.7 nm poly(alkyl acrylates) and poly(alkyl methacrylates) form a new absorption band around 280 nm. This band is assigned at least partly to aldehyde groups attached to the main-chain. Aldehyde groups formed upon irradiation of poly(methyl methacrylate) were converted to 2,4-dinitrophenylhydrazone groups and detected by absorption spectroscopy performed in conjunction with gel permeation chromatography. Quantum yields of carbonyl groups capable of reacting with 2,4-dinitrophenylhydrazine were determined: phi (CO) = 4.4 x 10(-4) (argon) and phi (CO) = 8.0 x 10(-4) (air).