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Description
Highly branched polyethylenes (HBPEs) synthesized via α-diimine nickel catalysis exhibit excellent thermoplastic elasticity due to the unique combination of long and short branching structures. It is, however, challenging to analyze the crystalline structure, crystallinity, and crystal size distribution of HBPEs due to their low crystallinity. Therefore, the relationship between the branching structure, solid structure, and mechanical properties has not been established. In this work, we provide a detailed structural characterization of various HBPEs by using solid-state 13C NMR spectroscopy combined with magnetic relaxation measurements. The combination of two 13C spin–lattice relaxation methods quantitatively analyzes the crystallinity, as well as size distributions of both the orthorhombic and monoclinic phases. By quantitatively comparing the detailed branching microstructures with crystallinity, it is established that HBPEs with long chain branching (LCB < 12b/1000C) and short-chain branching (SCB < 85 b/1000C) exhibit semicrystalline features. Furthermore, it was found that high fractions of small crystallites relative to the large ones, rather than crystallinity, lead to excellent strain recovery behavior. In conclusion, solid structures, including crystallinity, polymorph, and crystalline size distribution, govern the unique thermoplastic elasticity of HBPEs. This research provides guidance for designing branching microstructures for tunable solid structures and the mechanical properties of HBPEs.
Publisher name
American Chemical Society
Grant Information
N/A
Data Management
N/A
Document Type
Article
Digital Object Identifier (DOI) Link
https://doi.org/10.1021/acs.macromol.6c01367
Publication Date
6-17-2026
Publication Title
Macromolecules
Volume
59
Issue
14
First Page
8497
Last Page
8508
Recommended Citation
Miyoshi, Toshikazu; Eagan, James; Romano, Walter G.; and Turney, Keaton M., "Molecular Origins for Thermoplastic Elasticity of Highly Branched Polyethlene as Revealed by Solid-state NMR Spectroscopy" (2026). University Research. 62.
https://ideaexchange.uakron.edu/university_research/62
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.