Properties of Cationic Choline-Derived Surfactant with Photolabile Cinnamate Counterion

A cationic choline-derived surfactant with photolabile cinnamate counterion (tetradecyl-(2-hydroxyethyl)-dimethylammoniumcinnamate, C(14)HDACin) was synthesized. The properties of C(14)HDACin aqueous solutions for pre- or post-UV irradiation were investigated by employing tensiometry, conductance, transmission electron microscopy (TEM) and rheometry. The effect of UV irradiation time on photoisomerization of C(14)HDACin solutions was evaluated, which showed that the photoisomerization efficiency decreases with an increase of C(14)HDACin concentration. After UV irradiation, the fraction of counterion binding (beta) of the C(14)HDACin micelle decreases. However, the value of CMC increases. Rheometry coupled with TEM studies confirmed that the aggregation of C(14)HDACin could transform from wormlike to spherical micelles upon UV irradiation.