PHOTODEGRADATION OF LINEAR POLYKETONES DI FFERENTLY SUBSTITUTED WITH PHENYL GROUPS

The present work concerns the photodegradation of macromolecules havin g phenyl and carbonyl groups along the main chain. The photochemical b ehaviour of different polyketones is expected to give useful informati on about the mechanisms of the reaction. With this purpose we have con sidered polyketones constituted of 3-oxo-1,-1 diphenylbutane-1,4 diyl (I) units regularly head to tail linked, and polyketones of 3-oxo-1-2- diphenylbutane-1-4 diyl units (II and III). The synthesis of I by hydr olysis of polymers of 3 acetoxy-1,1-diphenylbutane-1-3 diene 2a and II , III by hydrolysis of polymers of 3-acetoxy-1,2 (and 1,4)-diphenylbut ane-1,3 (5a, 8a) were successful. The tests of polymerization of trime thylsiloxy monomers have not been conclusive; the photochemical behavi our of these polyketones is in good agreement with the previously obse rved mechanism of degradation of polyketones having alpha phenyl or be ta phenyl carbonyl groups.