Ordering Kinetics of the BCC Morphology in Diblock Copolymer Solutions over a Wide Temperature Range

Abstract

The morphology and order-to-disorder transition (ODT) of solutions of a low molecular weight poly(styrene-b-ethylene-alt-propylene) in squalane were studied by four different methods: DSC, modulated DSC, rheology, and small-angle X-ray scattering (SAXS). The ordering from disordered micelles to the BCC morphology was traced by both rheological and SAXS measurements. The ordering mechanism was found to follow the “nucleation and growth” pathway under both shallow and deep temperature quenches. The ordering process resembles the crystallization of semicrystalline polymers. The ordering half-time (t0.5) showed a clear minimum at an intermediate temperature. At temperatures far below the ODT temperature (TODT) but well above the glass transition temperatures of the solvent and the corona block of the micelles, t0.5 increased with concentration. The temperature dependence of the ordering process was analyzed using the Fredrickson−Binder theory. Following a shallow quench (TODT − T < 15 °C), t0.5 was found to ...