Diffusion of Homopolymers into Nonequilibrium Block Copolymer Structures. 1. Molecular Weight Dependence

The diffusion of deuteriated polystyrene (d-PS) and deuteriated poly(methyl methacrylate) (d-PMMA) into nonequilibrium symmetric diblock copolymer structures was studied by using elastic recoil detection (ERD). The diffusion coefficient, DHC, of the d-PS and d-PMMA homopolymer chains of degree of polymerization NH diffusing into the copolymer hosts was found to vary as NH-2 for chains where NH ≲ NC/2. NC is the total number of monomer segments of the copolymer chain. In cases where NK was sufficiently larger than Nc the dependence of DHC on NH was considerably greater than NH-2. DHC was found to be an order of magnitude lower than DHH, the diffusion coefficient of the homopolymer chains diffusing into their respective homopolymer hosts. It was found that varying the rate of solvent evaporation, changing the solvent used for preparing the samples, and preannealing the samples for sufficiently long periods of time before the diffusion process had a marked influence on the diffusional transport properties. © 1988, American Chemical Society. All rights reserved.