Azo polymers were reported to be prepared from polystyrene through a nitration-reduction-diazotization-coupling (NRDC) reaction route. However

azo-coupling rates of the products were rather low because of the several steps of macromolecular reaction with low reaction yield in each step

or the obtained azo polymers could not be dissolved in any solvent due to the use of cross-linked polystyrene as precursor．Recently

photoresponsive azo polymers have become actively researched objects

but no PS-based azo polymers have been used as photo-responsive polymers so far due to above reasons．In this work

three kinds of soluble polystyrene-based azo polymers with high coupling rates have been synthesized through a modified NRDC procedure from polystyrene matrix．Both steps of the nitration and the reduction have nearly 100％ reaction yields. Macromolecular diazonium salts (MDS) prepared were reacted with N-alkyl aniline

substituted aniline and phenol type compounds through the azo coupling reaction．The intermediates and final products were characterized by 1H-NMR

IR and UV-Vis spectroscopy．Even though high coupling rates were obtained

diazonium salt groups could not be totally consumed due to the steric hindrance in the macromolecular reactions．The decomposition and cross-linking of these residual diazo groups were found to be the reason for losing of solubility of the products．The thermolysis process of the diazonium salt group was studied and a heating step of reaction mixture was added after the azo coupling reaction．In this step

the unreacted diazo groups were converted to phenolic hydroxyl groups

which was found to be essential for preparing soluble PS-based azo polymers．