Issue 34, 2022

Determination of the critical chain length for macromolecular crystallization using structurally flexible polyketones

Abstract

Critical chain length that divides small molecule crystallization from macromolecular crystallization is an important index in macro-organic chemistry to predict chain-length dependent properties of oligomers and polymers. However, extensive research on crystallization behavior of individual oligomers has been inhibited by difficulties in their synthesis and crystallization. Here, we report on the determination of critical chain length of macromolecular crystallization for structurally flexible polyketones consisting of 3,3-dimethylpentane-2,4-dione. Discrete polyketone oligomers were synthesized via stepwise elongation up to 20-mer. Powder and single crystal X-ray diffraction showed that the critical chain length for polyketones existed at an unexpectedly short chain length, 5-mer. While shorter oligomers adopted unique conformations and packing structures in the solid state, higher oligomers longer than 4-mer produced helical conformations and similar crystal packing. The critical chain length helped with understanding the inexplicable changes in melting point in the shorter chain length region resulting from chain conformations and packing styles.

Graphical abstract: Determination of the critical chain length for macromolecular crystallization using structurally flexible polyketones

Supplementary files

Article information

Article type
Edge Article
Submitted
01 jun 2022
Accepted
21 jul 2022
First published
21 jul 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2022,13, 9848-9854

Determination of the critical chain length for macromolecular crystallization using structurally flexible polyketones

Y. Ide, Y. Manabe, Y. Inaba, Y. Kinoshita, J. Pirillo, Y. Hijikata, T. Yoneda, K. I. Shivakumar, S. Tanaka, H. Asakawa and Y. Inokuma, Chem. Sci., 2022, 13, 9848 DOI: 10.1039/D2SC03083G

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