Molecular-level relation between intra-particle glass transition temperature and stability of colloidal suspensions

In many colloidal suspensions, the dispersed colloidal particles are amorphous solids resulting from vitrification. A crucial open problem is understanding how colloidal stability is affected by the intra-particle glass transition. By dealing with the latter process from a solid-state perspective, we estabilish a proportionality relation between the intra-particle glass transition temperature, $T_{\textrm{g}},$ and the Hamaker constant, $A_\textrm{H},$ of a generic suspension of nanoparticles. It follows that $T_\textrm{g}$ can be used as a convenient parameter (alternative to $A_\textrm{H}$) for controlling the stability of colloidal systems. Within DLVO theory, we show that the novel relationship, connecting $T_\textrm{g}$ to $A_\textrm{H},$ implies the critical coagulation ionic strength (CCIS) to be a monotonically decreasing function of $T_{\textrm{g}}.$ We connect our predictions to recent experimental findings.