Copolymer morphology and function depends sensitively on copolymer sequence. However, controlling the sequences of synthetic copolymers continues to be a challenge. Recently, we have shown that even very weak inter-monomer attractions can spur aggregation among the polymerizing oligomers of a solution-based step-growth A,B-copolymerization. This emergent collective behavior among the growing chains – a consequence of the dependence of the phase behavior on chain length, as described by Flory-Huggins theory – can influence sequence as subsequent polymer bonds form. Depending on the types of non-bonded attractions, regions enriched in one monomer type can develop within these condensed nascent oligomer phases. In this work, we investigate these effects among semi-flexible oligomers using reactive Langevin Dynamics simulations. We find that homopolymer blocks of a characteristic length spontaneously form at longer persistence lengths, and that the size of these self-templated blocks changes with the relative diffusion and reaction time-scales. In addition, we find that a small number of seed homo-oligomers added to the start of the reaction can tune the lengths of the resulting homopolymer blocks. These observations provide potential routes to intentionally bias copolymer sequence within a scalable, one-pot reaction.

Modeling the self-templating and seeding of homopolymer blocks within a one-pot A,B-copolymerization

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