DIFFUSION IN MICROSTRUCTURED BLOCK-COPOLYMERS - CHAIN LOCALIZATION AND ENTANGLEMENTS

The diffusion (D(s)) of entangled and unentangled symmetric block copolymers is compared, above and below the ordering transition. The lamellar samples were not macroscopically oriented, and thus D(s) reflects a combination of mobilities parallel and perpendicular to the lamellar planes. For unentangled (Rouse) chains, D(s) is unaffected by the microstructure, whereas entangled (reptating) chains are retarded significantly; this difference reflects an interesting combination of thermodynamic and entanglement constraints. Furthermore, this retardation persists into the nominally disordered state.