Abstract
The mean-square displacement, <Delta r(2)>, of very high molecular
weight diblock copolymers in solutions near the disorder-to-order
transition is investigated by pulsed-field-gradient NMR. The
thermodynamic potential influencing the motion leads to a
time-independent <Delta r(2)> at short times followed by
free-diffusional behavior. The plateau is attributed to a trapping of
the copolymer chains at the “quasi-interfaces” formed by slow
composition fluctuations.