Ahmadian Dehaghani Zahra, Chubak Iurii, Likos Christos N, Ejtehadi Mohammad Reza
Department of Physics, Sharif University of Technology, P. O. Box 11155-9161, Tehran, Iran.
Soft Matter. 2020 Mar 28;16(12):3029-3038. doi: 10.1039/c9sm02374g. Epub 2020 Mar 4.
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 θ-point when the solvent quality is worsened. We mainly focus on poly[n]catenanes consisting of n ring polymers each of length m interlocked in a linear fashion. Using molecular dynamics simulations, we study the scaling of the poly[n]catenane's radius of gyration in a good solvent, assuming in general that R∼mn and we find that μ = 0.65 ± 0.02 and ν = 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 μ = 16/25 and ν = 3/5, consistent with the numerical results. We show that individual rings within catenanes feature a surplus swelling due to the presence of N topological links. Furthermore, we consider poly[n]catenanes in solvents of varying quality and we demonstrate that the presence of topological links leads to an increase of its θ-temperature in comparison to isolated linear and ring chains with the following ordering: T > T > T. Finally, we show that the presence of links similarly raises the θ-temperature of a single linked ring in comparison to an unlinked one, bringing its θ-temperature close to the one of a poly[n]catenane.
我们研究了由相互连接的环状聚合物组成的索烃中拓扑约束对其在良溶剂中的尺寸以及当溶剂质量变差时其θ点位置的影响。我们主要关注由n个长度为m的环状聚合物以线性方式互锁而成的聚[n]索烃。通过分子动力学模拟，我们研究了聚[n]索烃在良溶剂中回转半径的标度，一般假设R∼mn，并且我们发现在所考虑的n和m范围内，μ = 0.65 ± 0.02以及ν = 0.60 ± 0.01。借助产生μ = 16/25和ν = 3/5值的平均场类弗洛里理论，这些结果得到了进一步的合理解释，与数值结果一致。我们表明，由于存在N个拓扑连接，索烃中的单个环具有额外的溶胀。此外，我们考虑了处于不同质量溶剂中的聚[n]索烃，并且我们证明，与孤立的线性链和环状链相比，拓扑连接的存在导致其θ温度升高，顺序如下：T > T > T。最后，我们表明，与未连接的单个环相比，连接的存在同样会提高其θ温度，使其θ温度接近聚[n]索烃的θ温度。
