SIMULATION OF CHAIN MOLECULES IN SOLUTIONS AT FINITE CONCENTRATIONS UNDER SEVERAL SOLVENT CONDITIONS

Computer experiments simulating chain molecule solutions on a tetrahedral lattice have been performed at various concentrations and under several solvent conditions. In good and athermal solvents, mean squares of end to end distance 〈R2〉/b2 and of radius of gyration 〈S 2〉/b2 decrease monotonically with the increase in the concentration of chain molecules. In poorer solvents, the monotonic decrease was sometimes not found and in the solutions under very poor solvent conditions, they seemed to have a slight positive dependence on the concentration. The principal moments of inertia of chain molecules were also computed in this connection. The element density distributions around the mass center of a chain were also evaluated and discussed. The numbers of chain element to chain element and chain element to solvent contact pairs, which are closely related to the heat of mixing, were evaluated and compared with the prediction of the quasichemical theory. The agreement was good in good or athermal solvent solutions at moderate concentrations. The disagreement, however, was found in dilute solutions and in poorer solvent solutions. © 1979 American Institute of Physics.