1 research outputs found
Complex Morphology of the Intermediate Phase in Block Copolymers and Semicrystalline Polymers As Revealed by <sup>1</sup>H NMR Spin Diffusion Experiments
Nanostructured multiphase polymers
exhibiting a mobile and a rigid
phase also contain a phase of intermediate mobility that is usually
assumed to be a continuous, uninterrupted interphase layer. This assumption
is contrary to recent molecular-resolution micrographs and contradicts
results from NMR spin diffusion experiments, all of which suggest
a nontrivial interface structure. In this contribution, we reconsider
our previous <sup>1</sup>H NMR spin diffusion data sets (Roos Colloid. Polym. Sci. 2014, 292, 1825) and perform optimized 2D and 3D numerical spin diffusion calculations
to characterize the basic intermediate-phase morphological pattern,
thus overcoming previous inconsistencies in data fitting. For the
diblock copolymer poly(butadiene)-poly(styrene), PS<i>-<i>b</i>-</i>PB, we demonstrate that the interphase region
comprises nanometer-size intermixed immobile, intermediate and mobile
subregions. In contrast, for the semicrystalline polymer poly(ε-caprolactone),
PCL, the spin diffusion data are best reproduced by an intermediate
phase that is fully embedded within the rigid phase, which is attributed
to an imperfect crystalline structure. For both samples, the new findings
reveal a complex discontinuous, dynamically inhomogeneous structure
of the intermediate phase