REVERSIBLE PHOTODIMERIZATION OF OMEGA-ANTHRYLPOLYSTYRENES

The preparation of polystyrene with controlled molar masses and narrow dispersity endcapped with an anthrylmethyl ether group, as well as th e study of their photophysical properties, are described. Under irradi ation at 336 nm dimerisation of the polystyrene chains is observed. Th is process results from the formation of a symmetrical head-to-tail ph otodimer between two anthryl end groups. When irradiated at lower wave length (lambda = 228 nm), the original omega-anthrylpolystyrene chains are quantitatively restored. These dimerisation/dissociation cycles c an be conducted more than ten times without any detectable degradation of the photosensitive polymer. The fluorescence emission quantum yiel d and fluorescence lifetime of the omega-anthryl moieties and the quan tum yield of the dimerisation and of the reverse process have been mea sured.