Colloidal interactions mediated via polyelectrolytes

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Abstract
Using Monte Carlo simulation, scaling, variational and mean‐field arguments we investigate forces between charged spherical aggregates conferred by oppositely charged polymeric chains. Two types of polymer mediated attraction are found in this system, both of a bridging type but differing markedly in terms of the range. The entropic bridging force is of a range comparable to the average monomer–monomer separation in the chain. It is present whenever many chains have to compensate the charge on two macroions. The energetic bridging force has a range of the order of the length of the polymer chain and pertains to situations when a single chain has to compensate the charge on more than one macroion. In what follows we shall give a detailed analysis of both bridging interactions with a special regard for polycounterion versus simple counterion effects. The two types of bridging are in a certain sense complementary and should be present in polymer– surfactant systems at different regimes of the polymer–macroion concentration ratios.