E. Lee, T. Shakirov, and W. Paul
Institut für Physik, Martin-Luther Universität Halle-Wittenberg, 06099 Halle (Saale), Germany
Rheological properties of supramolecular polymers depend on their structures including the size, the number, and the topology of aggregates. A linear polymer with hydrogen bonding units at both ends is one of widely used precursors to build the supramolecular polymer networks. Due to complex interplay between chain stiffness, hydrogen bonding interaction, and polymer conformational entropy it is difficult to theoretically predict the structure of the supramolecular polymer. In this work, we investigate structures of supramolecular polyethylene glycol and polybutylene glycols whose ends are capable of the hydrogen bond using a coarse-grained (CG) model via stochastic approximation Monte Carlo simulation (SAMC) method. Our CG force field is constructed by Boltzmann inversion of the probability distributions of all-atom polymer conformations. SAMC provides all the thermodynamic information of the system, which allows one to investigate supramolecular structures in a wide temperature range. This work especially focuses on the transition from ring- to chain-dominated phases since the contaminant of rings in a melt is known to significantly influence its rheology. In a limit of dilute concentration, the transition temperature (T*) shows non-monotonous behavior as molecular weight of the precursor increases due to competition between chain stiffness and hydrogen bonding. We also investigate the polymer concentration (c) dependence on T* to construct a c-T phase diagram.