title: Quantitative study of fluctuation effects by fast lattice Monte Carlo simulations. V. incompressible homopolymer melts.
abstract: 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 ρ(0) ≥ 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 ρ(0) = 1) to the case of ρ(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 ρ(0), and that the leading order of non-Gaussian fluctuation effects on the single-chain properties is inversely proportional to ρ(0)(2). 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 ρ(0) ≥ 2 in two and three dimensions.
authors.affiliation: Department of Chemical and Biological Engineering, Colorado State University , Fort Collins, Colorado 80523-1370, United States.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Zhang
authors.forename: Delian
authors.initials: D
authors.lastname: Yang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004058:Diffusion; D008956:Models, Chemical; D009010:Monte Carlo Method; D009038:Motion; D011108:Polymers / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D011108:Polymers