INFLUENCE OF THE SOLVENT SIZE ON THE BEHAVIOR OF MODEL-POLYMERS IN SOLUTION

Two-dimensional chains with N-c=4 up to N-c=20 segments are investigat ed by hard disks molecular dynamics simulations. Solvent particles are explicitly taken into account. In addition, the ratio sigma(s)/sigma( c) of the diameters of the solvent molecules sigma(s) and the chain se gments sigma(c) is varied between 0.5 less than or equal to sigma(s)/s igma(c) less than or equal to 40.0. Several equilibrium properties sho w that the polymer dimensions strongly depend on the solvent size. The data are compared to results obtained for a single chain generated by a Monte Carlo simulation. Studies of the mean square (m.sq.) end-to-e nd distance [R(2)], the m.sq, radius of gyration [S-2] and some distri bution functions indicate that the polymer coil becomes more compact i n the presence of solvent molecules. Irrespective of N-c the most coil ed configurations are found for systems with sigma(s)/sigma(c)=1. For very large sigma(s)/sigma(c) all quantities considered correctly appro ach the values found for isolated chains. (C) 1995 American Institute of Physics.