Random copolymers in concentrated solutions

¹ Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
² Service de Chimie Moleculaire, CE-Saclay - 91191 Gif-sur-Yvette Cedex, France

Received: 2 April 1996
Accepted: 4 July 1996

Abstract

We study concentrated solutions of ideal A-B symmetric random copolymers in non-selective good solvents by computer simulations. When the effective net A-B interaction per thermal energy in the solution () is larger than 2, the scattering function has a peak at a molecular weight (N) independent wave vector . We find a certain characteristic cell size below which the distribution of local monomer densities within the system is flat, i.e. the probability of finding a cell with an A monomer density is uniform over a broad range of values. We observe solvent enrichment in cells where and solvent depletion in cells which are either A or B rich. The chains dynamics for all N studied (up to N=64) are Rouse-like regardless of the value of . When reptation dynamics are imposed, the diffusion of the center of mass decreases substantially as increases, suggesting that long chains are quasi-frozen.