Electrostatic Self-Assembled Multilayers from Side Chain Azo Polyelectrolytes

Photoresponsive behavior and self assembly properties of three side chain azo polyelectrolytes, poly (2 (4 phenylazophenoxy) ethanol co acrylic acid) (PPAPE), poly (2 (4 (4′ nitrophenylazo) phenoxy) ethanol co acrylic acid) (PNAPE), and poly (2 (4 (4′ ethoxyphenylazo) phenoxy) ethanol co acrylic acid) (PEAPE), were studied. These polyelectrolytes with different degrees of functionalization of azo chromophores were fabricated into nano composite multilayers using two types of dipping solutions through a layer by layer electrostatic self assembling process. Results show that the ratio between tetrahydrofuran (THF) and H 2O significantly influences the photoresponsive behavior of PNAPE in THF H 2O mixture. The THF H 2O dipping solution, used in this work for self assembly of hydrophobic polyelectrolytes, is proved to be as applicable as aqueous dipping solution for normal self assembly of hydrophobic polyelectrolytes. However, significant differences in the multilayer growth between the two systems were also observed, which resulted from the remarkable difference of the existing forms of the polyelectrolytes in these two dipping solutions. 