Structure and Dynamics of Dilute Two-Dimensional Ring Polymer Solutions

초록

Structure and Dynamics of dilute two-dimensional (2D) ring polymer solutions are investigated by using discontinuous molecular dynamics simulations. A ring polymer and solvent molecules are modeled as a tangent-hard disc chain and hard discs, respectively. Some of solvent molecules are confined inside the 2D ring polymer unlike in 2D linear polymer solutions or three-dimensional polymer solutions. The structure and the dynamics of the 2D ring polymers change significantly with the number (N-in) of such solvent molecules inside the 2D ring polymers. The mean-squared radius of gyration (R-2) increases with N-in, and scales as R similar to N-v with the scaling exponent v that depends on N-in. When N-in is large enough, v approximate to 1, which is consistent with experiments. Meanwhile, for a small N-in approximate to 0.66 and the 2D ring polymers show unexpected structure. The diffusion coefficient (D) and the rotational relaxation time (tau(rot)) are also sensitive to N-in: D decreases and tau increases sharply with N-in. D of 2D ring polymers shows a strong size-dependency, i.e., D similar to In(L), where L is the simulation cell dimension. But the rotational diffusion and its relaxation time (tau(rot)) are not-size dependent. More interestingly, the scaling behavior of tau(rot) also changes with N-in; for a large N-in tau(rot) similar to N-2.46 but for a small N-in tau(rot) similar to N-1.43.

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