Synthesis, photochemical and photoinitiation activity of water-soluble copolymers with anthraquinone chromophores as side-chain groups

Novel water-soluble anthraquinone copolymers are synthesised by copolymerisation of 2-acryloxy and 2-acrylamido anthraquinone monomers at 1–2% w/w concentration with three water-soluble co-monomers: acrylamide, 2-acrylamido-2-methylpropane sulphonic acid and 2-acryloxyethyl trimethylammonium iodide. The proton and the iodide were replaced on the corresponding obtained copolymers by sodium and chloride using ionic exchange resins. The absorption, phosphorescence (in methanol), photoreduction and microsecond flash photolysis characteristics of the new copolymers are examined in aqueous solution and the results compared with those of a water-soluble low molecular weight anthraquinone, 2-(N,N,N-trimethylammoniumpropoxy) anthraquinone chloride, also synthesised in this work. The photoinduced polymerisation activities of the new products are evaluated by photodilatometry in the presence of triethanolamine as a hydrogen donor. The acrylate anthraquinone copolymers exhibit similar rates and quantum yields of polymerisation to those of the model, while lower values for the acrylamide anthraquinone copolymers are found. The polymerisation activity correlates well with their measured photoreduction quantum yields in water using triethanolamine as the cosynergist.