  In systems of highly charged linear polyelectrolytes and oppositely charged
colloidal particles, long-lived clusters of polyelectrolyte-decorated particles
form in an interval of concentrations around the isoelectric point, where
reentrant condensation connected to charge inversion of cluster is observed.
The mechanisms that drive the aggregation and stabilize, at the different
polymer/particle ratios, a well defined size of the aggregates are not
completely understood. Moreover, a central question still remains unanswered,
i.e., whether the clusters are true equilibrium or metastable aggregates. To
elucidate this point, in this work, we have investigated the effect of the
temperature on the formation of the clusters. We employed liposomes built up by
DOTAP lipid interacting with a simple anionic polyion, sodium polyacrylate,
over an extended concentration range below and over the isoelectric condition.
Our results show that the aggregation process can be described by a
thermally-activated mechanism.
