Novel water soluble copolymers based on thioxanthone: photochemistry and photoinitiation activity

The absorption, luminescence and photoreduction properties of five novel water soluble thioxanthone copolymers are reported. The new polymers have been prepared by copolymerization of 1-methyl-4-(3-acryloxypropoxy) thioxanthone (TX3), 1-chloro-4-acryloxy thioxanthone (TX4), 1-chloro-4-oxyethylacrylate thioxanthone (TX5), and 1-chloro-4-allyloxy thioxanthone (TX6), with two water soluble comonomers, acrylamide (AAm) and 2-acryloxyethyl trimethylammonium iodide (MI). otoinitiation effectiveness of these new copolymers was studied by photocalorimetry and photodilatometry for acrylamide photopolymerization in aqueous solution and in the presence of a tertiary amine. The results compared to those of the corresponding low molecular weight model compounds, (TX1), 1-methyl-4-(2-hydroxy-3-N,N,N-trimethylammoniumpropoxy) thioxanthone chloride salt, and TX2, 1-chloro-4-(2-hydroxy-3-N,N,N-trimethylammoniumpropoxy) thioxanthone chloride salt. The new copolymers show high polymerisation rates under the experimental conditions used, and confirm that these compounds operate as effective photoinitiators of polymerization. The data are discussed in relation to their photophysical and photochemical properties.