Unravelling the crystal and molecular structure of a 1,3-linked aromatic poly(ether-ketone)

Aldred, P. L., Leroux, F., Colquhoun, H. M. and Aricò, F. (2022) Unravelling the crystal and molecular structure of a 1,3-linked aromatic poly(ether-ketone). Materials Today - Chemistry, 24. 100853. ISSN 2468-5194 doi: 10.1016/j.mtchem.2022.100853

Abstract/Summary

Highly-oriented fibres of the aromatic polyetherketone [-O(1,4-Ar)CO(1,3-Ar)CO(1,4-Ar)-]n (Ar = phenylene) obtained by nucleophilic polycondensation of F(1,4-Ar)CO(1,3-Ar)CO(1,4-Ar)F with HO(1,4-Ar)CO(1,3-Ar)CO(1,4-Ar)OH afford, after annealing, very well-resolved X-ray fibre patterns. The new diffraction data are used to test two different published models for the crystal and molecular structure of this polymer, both based on a three-ring crystallographic repeat, and it is shown by diffraction-modelling that neither of these structures is compatible with the new fibre-data. In contrast, we report a novel structure, based on a six-ring crystallographic repeat, that gives a simulated fibre-diffraction pattern in very good agreement with the experimental pattern. Crystal data for the new structure are: orthorhombic, space group Pcam, a = 7.67, b = 6.13, c = 29.72 Å, two chains per cell, V = 1397 Å3, density = 1.43. Unusually, the two chains in the unit cell are related by an a-glide, meaning that the carbonyl groups in the two chains are aligned anti-parallel rather than having the more generally found parallel arrangement resulting from the presence of a b-glide. The new structure is shown to be fully compatible with previously published X-ray powder and electron diffraction data.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/103366
Identification Number/DOI	10.1016/j.mtchem.2022.100853
Refereed	Yes
Divisions	Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Xray (CAF)
Publisher	Elsevier
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