The temperature dependence of the micellisation of chlorpromazine hydrochloride in aqueous solution

The association characteristics of the weakly associating drug chlorpromazi ne hydrochloride have been examined over the temperature range 10-35 degree s C by means of conductimetric measurements. Critical micelle concentration s (cmc) have been determined by the application of a recently developed num erical method [Perez-Rodriguez et al. (1998) Langmuir 14:4422] especially d esigned for the analysis of the association pattern in highly polydisperse systems of low aggregation number. The cmcs determined in this manner are u sed in combination with the mass-action model to obtain the thermodynamic p arameters of the micellisation process, in particular the surface and hydro phobic contributions to the free energy. The use of exact forms of equation s for the thermodynamics of micellisation applicable to systems of low aggr egation number leads to values of the enthalpy of micellisation in reasonab le agreement with experimentally determined values.