Surface activities and thermodynamic properties of novel cationic surfactants with hydroxymethyl group

<p>A new series of cationic surfactants, <i>N</i>–alkyl–<i>N,N</i>–dimethyl–<i>N</i>–(<i>p</i>–(hydroxymethyl) benzyl) ammonium chlorides (<i>p</i>-DHBA<i>-m</i>), were synthesized and the structures were characterized by ¹HNMR, ¹³CNMR, FT–IR and ESI–MS. The surface activities, thermodynamic properties and aggregation behaviors of <i>p</i>-DHBA<i>-m</i> in aqueous solutions were respectively studied by means of surface tension, isothermal titration calorimetry and steady-state fluorescence methods. Thermodynamic parameters show that the micellization is an entropy-driven process. According to the fluorescence quenching method, the micelle aggregation numbers (<i>N</i>_agg) of <i>p</i>-DHBA-<i>m</i> were calculated and found that the increase of temperature or the elongation of alkyl chain length could lead to the reduction of the <i>N</i>_agg, respectively.