Effects of topological constraints on linked ring polymers in solvents of varying quality

ZA Dehaghani and I Chubak and CN Likos and MR Ejtehadi, SOFT MATTER, 16, 3029-3038 (2020).

DOI: 10.1039/c9sm02374g

We investigate the effects of topological constraints in catenanes composed of interlinked ring polymers on their size in a good solvent as well as on the location of their theta-point when the solvent quality is worsened. We mainly focus on polyncatenanes consisting of n ring polymers each of length m interlocked in a linear fashion. Using molecular dynamics simulations, we study the scaling of the polyncatenane's radius of gyration in a good solvent, assuming in general that R-g similar to m(mu)n(nu) and we find that mu = 0.65 +/- 0.02 and nu = 0.60 +/- 0.01 for the range of n and m considered. These findings are further rationalized with the help of a mean-field Flory- like theory yielding the values of mu = 16/25 and nu = 3/5, consistent with the numerical results. We show that individual rings within catenanes feature a surplus swelling due to the presence of N-L topological links. Furthermore, we consider polyncatenanes in solvents of varying quality and we demonstrate that the presence of topological links leads to an increase of its theta-temperature in comparison to isolated linear and ring chains with the following ordering: T theta catenane > T theta linear > T theta ring. Finally, we show that the presence of links similarly raises the theta-temperature of a single linked ring in comparison to an unlinked one, bringing its theta- temperature close to the one of a polyncatenane.

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