The dynamics of individual components in 1,4-polyisoprene/poly(vinylethylene) miscible blends are studied using two-dimensional deuteron exchange NMR. The rate of the backbone reorientation process near the glass transition is quantitatively determined for each species in a miscible blend as a function of temperature. We demonstrate that the broad glass transition arises both from a wide distribution of segmental motional rates for each species and from intrinsic differences in the motional rate between the two species.In addition, the temperature dependence of their motional rates in the blend DSC glass transition region suggests that the two components undergo distinct effective glass transitions, which is consistent with previously observed thermorheologically complex behavior. The origins of dynamic heterogeneity are examined further by comparing the experimental results with a simple model calculation that takes into account the effect of composition variations in an ideal miscible blend. This comparison suggests that the observed dynamic heterogeneities can be explained only by including two distinct contributions: local composition variations in the blend and intrinsic differences in chain mobilities.

The segmental motion of each species in polyisoprene/poly(vinylethylene) (PI/PVE) miscible blends is studied at three different compositions using two-dimensional deuteron exchange NMR (2D 2H NMR). The individual species exhibit widely different mean mobilities and broad mobility distributions near the glass transition of each blend. As the PVE content increases, both the difference in mean mobilities between the two species and the width of the mobility distribution for both components increase. The change in these two types of dynamic heterogeneity with PVE content appears to produce the anomalous broadening of the glass transition. The mean reorientational correlation times of each component can differ by 2 orders of magnitude under identical conditions. This difference can be described in terms of distinct effective glass transition temperatures, Tg*, for the two species. The separation between the two effective glass transition temperatures increases almost monotonically with PVE content, consistent with the more pronounced thermorheological complexity of blends rich in PVE. The individual Tg*' s also exhibit a different compositional dependence from that of the calorimetric Tg of the blend observed by differential scanning calorimetry (DSC). This behavior can give rise to the complex compositional dependence of individual mobilities, apparent when the mobilities are compared at the same T -Tg with respect to the DSC Tg of the blend.

Alignment of lamellar block copolymer microstructure in an electric field was studied. Two mechanisms of alignment are considered: selective electric-field-induced disordering and alignment through movement of defects. The latter mechanism is supported by the findings that, in an aligned sample, defect structures exhibited a highly anisotropic arrangement and were spatially clumped. An analysis of fieldinduced forces on disclination lines and defect walls is presented. Also, defect interactions are considered. Through the interplay between these forces, the alignment process, the kinetics of alignment, and clumping of defects can be rationalized.

Diblock copolymers in a selective solvent often assemble into spherical micelles. These micelles demonstrate long range order at moderate polymer concentrations. We explore the nature of the disorder-order transition in micellar suspensions through small angle x-ray diffraction studies. The phase behavior includes body-centered cubic (bcc) and face-centered cubic (fee) lattices. We present the first phase diagram for block copolymer micelles to include both bcc and fee structures and characterize the lattice selection by a ratio of coronal layer thickness to core radius.