  We investigate the copolymerization behavior of a two-component system into
quasi-linear self-assemblies under conditions that interspecies binding is
favored over identical species binding. The theoretical framework is based on a
coarse-grained self-assembled Ising model with nearest neighbor interactions.
In Ising language, such conditions correspond to the anti-ferromagnetic case
giving rise to copolymers with predominantly alternating configurations. In the
strong coupling limit, we show that the maximum fraction of polymerized
material and the average length of strictly alternating copolymers depend on
the stoichiometric ratio and the activation free energy of the more abundant
species. They are substantially reduced when the stoichiometric ratio
noticeably differs from unity. Moreover, for stoichiometric ratios close to
unity, the copolymerization critical concentration is remarkably lower than the
homopolymerization critical concentration of either species. We further analyze
the polymerization behavior for a finite and negative coupling constant and
characterize the composition of supramolecular copolymers. Our theoretical
insights rationalize experimental results of supramolecular polymerization of
oppositely charged monomeric species in aqueous solutions.
