= Charge stabilization of colloids
Like-charged <colloids> can resist aggregation because bringing their <electric double layers> together costs <free energy>. In <DLVO theory>, screened electrostatic repulsion competes with attractive <Van der Waals forces>. A repulsive barrier much larger than $k_BT$ suppresses thermally activated aggregation, although the dispersion can remain metastable. Lower <ionic strength> generally lengthens the <Debye–Hückel screening length>, while multivalent <counterions> or added salt shorten it and can lower the barrier. The surface charge, charge regulation and solvent-dependent attraction also matter; screening length alone does not guarantee stability.
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