PHOTOCHEMICAL MODIFICATION OF A POLYMER SURFACE WITH PHENOTHIAZINE-BASED DUAL-FUNCTION DYES
We have studied the photochemical surface modification of polyethylene terephthalate (PET ) by a number of synthesized amides of toluidine blue ( TBO ) with 2-, 3- and 4-substituted azidobenzoic acids. TBO-4-azidobenzoate of a concentration of 3×10 -3 M and TBO-3-azidobenzoate were found to be the most/least modifiers by comparing PET film UV spectra before and after the photochemical modification. This is obviously related to the partial stabilization and lifetime increase of 2- and 4-substituted arylnitrenes due to the shift of the electron density from nitrene to an electron-withdrawing substituent. The lifetime increase leads to an increased probability of bimolecular reactions and, therefore, to the effective introduction into the C=O bond of the polymer matrix.