Aggregation and self-organization of hydrophilic azobenzene dye Langmuir-Blodgett films

Langmuir-Blodgett (LB) films of azobenzene dye of 2-hydroxyl-3-(4-methoxyl)-naphthanilide-azodiphenyl (AS-RL) and its hybrid films with behenic acid (BA) and octadecylamine (ODA) were investigated by tapping mode atomic force microscopy and ultraviolet visible light absorption spectroscopy. Wavy line-shaped or fingerprint-like dye aggregates were observed in the pure dye LB films. BA and ODA were used to modulate and control the structure of the dye aggregates and different patterns resulted in changing the molar ratio of dye molecules in the composites films, such as long lines (AS-RL/BA = 1:2), sheets (AS-RL/ODA = 1:2), wide lines (AS-RL/ODA = 1:1), and ordered lines (AS-RL/ODA = 2:1).