Quantitative Study of Fluctuation Effects by Fast Lattice Monte Carlo Simulations. V. Incompressible Homopolymer Melts

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• 作者：Pengfei Zhang ; Delian Yang ; Qiang Wang
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：October 16, 2014
• 年：2014
• 卷：118
• 期：41
• 页码：12059-12067
• 全文大小：393K
• ISSN：1520-5207

文摘

Using fast lattice Monte Carlo (FLMC) simulations (Wang, Q. Soft Matter 2009, 5, 4564) and the corresponding polymer lattice field theories, including the lattice self-consistent field and Gaussian-fluctuation (LGF) theories, we studied a model system of incompressible homopolymer melts on a hexagonal lattice, where each lattice site is occupied by a total of 蟻₀ 鈮?1 polymer segments. We generalized the cooperative motion algorithm (Pakula, T. Macromolecules 1987, 20, 679), as well as the related vacancy diffusion algorithm (Reiter, J.; Edling, T.; Pakula, T. J. Chem. Phys. 1990, 93, 837), originally proposed for the self- and mutual-avoiding walk (where 蟻₀ = 1) to the case of 蟻₀ > 1, where our generalized algorithm is highly efficient (i.e., nearly rejection-free). On the other hand, we extended the method of Wang (Wang, Z.-G. Macromolecules 1995, 28, 570) to calculate various single-chain properties in LGF theory. Direct comparisons between FLMC and LGF results, both of which are based on the same Hamiltonian (thus without any parameter-fitting between them), unambiguously and quantitatively reveal the effects of non-Gaussian fluctuations neglected by the latter. We found that FLMC results approach LGF predictions with increasing 蟻₀, and that the leading order of non-Gaussian fluctuation effects on the single-chain properties is inversely proportional to 蟻₀². Our work suggests that theories capturing the first-order non-Gaussian fluctuation effects may give quantitative agreement with FLMC simulations of incompressible homopolymer melts at 蟻₀ 鈮?2 in two and three dimensions.