An enthalpic analysis on the aggregation of colloidal particles studied bymicrocalorimetry

There are different theories concerning the stability of colloidal suspensi ons. Most of them arise from the well-known DLVO theory which relates collo idal stability to intermolecular forces between particles. Experimental cor roboration of these theories has been obtained mainly by using different op tical techniques that analyze changes in the optical properties of the solu tion while particles aggregate. However, no attention has been paid to stud ying the aggregation process thermodynamically. This is why we have focusse d on studying the heat released during the agglutination of polystyrene par ticles. The enthalpy change in this aggregation process was detected by usi ng a highly sensitive and modern technique called isothermal titration calo rimetry. In addition, some results about repeptization, that is, reversibil ity in the aggregation process, are also shown. (C) 2001 Academic Press.