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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 33, Number 3
BKCSDE 33(3)
March 20, 2012 

Structure and Dynamics of Dilute Two-Dimensional Ring Polymer Solutions
Younghoon Oh, Hyun Woo Cho, Jeongmin Kim, Chang Hyun Park, Bong June Sung*
Ring polymer, Molecular dynamics, Two-dimensions, Confinement
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 (Nin) of such solvent molecules inside the 2D ring polymers. The mean-squared radius of gyration (R2) increases with Nin and scales as R ~ Nν with the scaling exponent ν that depends on Nin. When Nin is large enough, ν ≈ 1, which is consistent with experiments. Meanwhile, for a small Nin ≈ 0.66 and the 2D ring polymers show unexpected structure. The diffusion coefficient (D) and the rotational relaxation time (τrot) are also sensitive to Nin: D decreases and τ increases sharply with Nin. D of 2D ring polymers shows a strong size-dependency, i.e., D ~ ln(L), where L is the simulation cell dimension. But the rotational diffusion and its relaxation time (τrot) are not-size dependent. More interestingly, the scaling behavior of τrot also changes with Nin; for a large Nin τrot ~ N2.46 but for a small Nin τrot ~ N1.43.
975 - 979
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