Photomodulation of the hydrophilic properties of acrylic polymers containing side-chain azobenzene chromophores

摘要

Partially hydrophilic polymers have been prepared by free-radical copolymerization of trans-4-acryloyloxyazobenzene with N-tert-butylacrylamide and N-isopropylacrylamide. A turbidimetric method has been adapted to investigate the dependence of the polymer hydrophilic-hydrophobic balance on chemical composition and extent of photoisomerization of side-chain azobenzene chromophores. Irradiation at 366 nm of polymer suspension in THF-water induces the isomerization of azobenzene groups from the planar apolar trans form to the nonplanar polar cis form. Correspondingly, the solution turbidity is appreciably modified. Experimental results are discussed in terms of polymer structural parameters. Suspension stability and the possibility of carrying out photochemical cycles have been also investigated.