NMR study of the morphology of polystyrene linear/microgel blends

Citation
Kj. Mcgrath et al., NMR study of the morphology of polystyrene linear/microgel blends, MACROMOLEC, 33(22), 2000, pp. 8354-8360
Citations number
71
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
MACROMOLECULES
ISSN journal
00249297 → ACNP
Volume
33
Issue
22
Year of publication
2000
Pages
8354 - 8360
Database
ISI
SICI code
0024-9297(20001031)33:22<8354:NSOTMO>2.0.ZU;2-6
Abstract
The morphology of blends of polystyrene (PS) microgels with linear PS were studied using NMR spectroscopy. Three techniques were employed to assess th e intimacy of mirdng: isothermal;cross-polarization/magic angle-spinning (C P/MAS) dipolar dephasing C-13 NMR, temperature-dependent 13C CP/ MAS NMR, a nd one-pulse H-1 MAS NMR. The experimental data reveal that linear PS can p enetrate: the core of soft microgels, whose network strands are substantial ly larger than the linear chains. However when the microgel is highly cross -linked, such penetration is prevented. These results are in accord with Fl ory-Huggins swelling theory. Blends of linear PS with highly cross-linked m icrogels yield thermodynamically stable morphologies, in which the componen ts are molecularly dispersed, yet segmental contacts are virtually absent. Such a phase morphology is novel and cannot be obtained with-conventional p olymer blends.