Mc. Dalvi et al., DIFFUSION IN MICROSTRUCTURED BLOCK-COPOLYMERS - CHAIN LOCALIZATION AND ENTANGLEMENTS, Physical review letters, 71(16), 1993, pp. 2591-2594
The diffusion (D(s)) of entangled and unentangled symmetric block copo
lymers is compared, above and below the ordering transition. The lamel
lar 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 mic
rostructure, whereas entangled (reptating) chains are retarded signifi
cantly; this difference reflects an interesting combination of thermod
ynamic and entanglement constraints. Furthermore, this retardation per
sists into the nominally disordered state.