Issue 11, 2025

Elucidation of the nano-sized molecular structure of methylaluminoxane using synchrotron X-ray total scattering

Abstract

Methylaluminoxane (MAO) is commonly employed to activate molecular pre-catalysts in polyolefin synthesis, both industrially and in the laboratory. Despite the extensive use of this compound, the ambiguity related to its structure hampers the understanding of its structure–function relationship. The current study therefore employed synchrotron X-ray total scattering to elucidate the nano-sized molecular structure of MAO. The MAO samples, which were prepared using various synthetic protocols, exhibited consistent X-ray scattering patterns and atomic pair distribution function curves, indicating similar molecular structures. However, the scattering intensity in the small-angle region revealed differences in the higher-order structures. A fitting study performed using 172 molecular models showed that small molecule and tube models were inadequate to reproduce the experimental results, whereas cage and sheet models provided comparably better fits. The sheet model was found to be consistent with the observed molecular weight and the molecular weight distribution, in addition to accounting for the intensity in the small-angle scattering region. These results align with recent crystallographic findings reported in Science, where a stacked sheet model successfully reproduced an experimental X-ray diffraction pattern. Ultimately, determination of the structural motif of MAO is expected to be beneficial for systematic research and development using this compound.

Graphical abstract: Elucidation of the nano-sized molecular structure of methylaluminoxane using synchrotron X-ray total scattering

Supplementary files

Article information

Article type
Paper
Submitted
09 Dec 2024
Accepted
21 Jan 2025
First published
18 Feb 2025
This article is Open Access
Creative Commons BY-NC license

Nanoscale, 2025,17, 6767-6779

Elucidation of the nano-sized molecular structure of methylaluminoxane using synchrotron X-ray total scattering

T. Wada and T. Taniike, Nanoscale, 2025, 17, 6767 DOI: 10.1039/D4NR05188B

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