Chain Diffusion in Lamellar Block Copolymers

Abstract

Diffusion of symmetric diblock copolymer chains in macroscopically oriented lamellar block copolymers are studied in a molecular dynamics simulation. Results for diffusion constant both parallel $D_{\parallel }$ and perpendicular $D_{\perp }$ to the lamellar planes are compared to results in the disordered one phase region. For diblocks of length N=40 (1.1 N_e) and $100(3N_e)$, where $N_e$ is the entanglement length of a homopolymer melt at the same density, $D_{\parallel }$ is nearly independent of $\chi$, while $D_{\perp }$ is strongly suppressed as $\chi$ is increased. These results are in agreement with theoretical predictions based on the Rouse model. The isotropic diffusion constant of quenched disordered systems is approximated fairly well by $(2D_{\parallel }+D_{\perp })/3$ of the corresponding lamellar system.

arXiv commentRevtex 12 pages, 4 postscript figures, uses psfig