Monte Carlo simulations and integral equation theory for the structure of telechelic polymers

Abstract

The structure of telechelic polymers is investigated using off-lattice Monte Carlo simulations and the polymer reference interaction site model (PRISM) integral equation theory. The polymer molecules are modeled as tangent-sphere freely-jointed chains where all beads interact via a hard sphere potential and end beads interact via an additional short-ranged attractive potential. The static properties, i.e., conformational properties, end-bead aggregation, intermolecular pair correlations, and partial static structure factors are investigated as a function of density and temperature. For a given density, as the temperature is lowered, the chain ends aggregate to form multiplets. For a given temperature, this tendency is greater at higher densities. Predictions of the PRISM theory for the pair correlation functions and partial static structure factors are compared to the simulation results. Three different closure approximations, the reference-Molecular mean spherical approximation (R-MMSA), the reference-molecular Percus–Yevick closure with the high temperature approximation (R-MPY/HTA), and the linearized form of the R-MPY/HTA, are tested. At high temperatures, the linearized R-MPY/HTA and R-MMSA closures are in good agreement with the simulations, but the R-MPY/HTA closure underestimates the correlation between monomers. At low temperatures, when multiplets are formed, none of the closures are accurate for the pair correlation functions or the partial static structure factors.