Chain trapping in diblock copolymers near the ordering transition

Abstract

The mean-square displacement, 〈Δr2〉, 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 〈Δr2〉 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.