NMR Methods for Characterization of Synthetic and Natural Polymers
Chapter 10: NMR Investigations of Interfaces in Tapered and Inverse-tapered Copolymers in the Solid State
Published:29 Jul 2019
Special Collection: 2019 ebook collectionSeries: New Developments in NMR
N. T. Pickering and J. L. White, in NMR Methods for Characterization of Synthetic and Natural Polymers, ed. R. Zhang, T. Miyoshi, and P. Sun, The Royal Society of Chemistry, 2019, ch. 10, pp. 211-230.
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A review of recent literature reveals that magnetic resonance experiments can quantify interfacial chain content in tapered and inverse-tapered copolymers in their end-use, solid-state forms. Chemically dissimilar chain segments organize into nanoscale domains according to copolymer chain structure, sizes for which depend upon whether diblock or multiblock versions of discrete, tapered, or inverse-tapered chain designs are used. Broad calorimetric glass-transitions can be further resolved through variable-temperature solid-state MAS NMR methods, revealing that some high-Tg components in copolymers can exhibit dynamics usually associated with low-Tg polymers, while some low-Tg components can exhibit chain dynamics characteristic of high-Tg polymer segments. The amount, distribution, and temperature-dependence of this dynamic and compositional heterogeneity can be systematically varied for copolymers with the same chemical composition by tailoring the arrangement of monomers in the chain. In sequence-controlled copolymers of styrene and butadiene, comparison to microscopy data indicates that solid-state NMR methods can quickly and non-invasively yield reasonable estimates of interphase fractions by quantifying “rigid butadiene” and “mobile styrene” segments in their tapered and inverse-tapered copolymers. These developments in which solid-state NMR has been used to understand relationships between chain structure, overall morphology, and differential ordering and dynamics within and between interfaces resulting from sequence-controlled polymerizations are reviewed and described in a format suitable for non-NMR specialists.