A side-chain azo polyelectrolyte

poly(2-[4一(4′-carboxyphenylazo)phenoxy]ethyl acrylate) (PCAPEA) was synthesized through free radical polymerization．Influences of solution pH values on the UV-Vis absorption spectra and photo-responsive behaviors of PCAPEA in aqueous solution were studied．The results showed that the UV-Vis absorption spectra of PCAPEA in aqueous solutions change with the solution pH value

and its photo-responsive behaviors also significantly depend on the solution pH value. This observation indicated that ionization degree changing with pH variation controls the existing conformation or aggregation of PCAPEA in the solution．PCAPEA not only in aqueous solution but also in water-tetrahydrofuran mixture was successfully fabricated into self-assembled multilayers with poly(diallydimethylammonium chloride)by an electrostatic layer-by-layer process．This new self-assembly technology supplied a feasible way for the electrostatic self-assembly of the polyelectrolytes with poor aqueous solubility．