Wiggins, Kelly M., Syrett, Jay A., Haddleton, David M. and Bielawski, Christopher W.. (2011) Mechanically facilitated retro [4 + 2] cycloadditions. Journal of the American Chemical Society, Vol.133 (No.18). pp. 7180-7189. ISSN 0002-7863

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Abstract

Poly(methyl acrylate)s (PMAs) of varying molecular weights were grown from a [4 + 2] cycloaddition adduct of maleimide with furan containing two polymerization initiators. Subjecting the corresponding PMA (>30 kDa) chains to ultrasound at 0 °C resulted in a retro [4 + 2] cycloaddition reaction, as observed by gel permeation chromatography (GPC) and UV−vis spectroscopy, as well as labeling of the liberated maleimide and furan moieties with appropriate chromophores featuring complementary functional groups. Similar results were obtained by sonicating analogous polymers that were grown from a thermally robust [4 + 2] cycloaddition adduct of maleimide with anthracene. The generation of anthracenyl species from these latter adducts allowed for the rate of the corresponding mechanically activated retro [4 + 2] cycloaddition reaction to be measured. No reduction in the number average molecular weight (Mn) or liberation of the maleimide, furan, or anthracene moieties was observed (i) for polymers containing the cycloaddition adducts with Mn < 20 kDa, (ii) for high molecular weight PMAs (Mn > 60 kDa) featuring terminal cycloaddition adducts, or (iii) when the cycloaddition adducts were not covalently linked to a high molecular weight PMA. Collectively, these results support the notion that the aforementioned retro [4 + 2] cycloaddition processes were derived from a vectorially opposed mechanical force applied to adducts embedded within the polymer chains.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Divisions:	Faculty of Science > Chemistry
Library of Congress Subject Headings (LCSH):	Polymerization, Organic compounds -- Synthesis, Mechanical chemistry
Journal or Publication Title:	Journal of the American Chemical Society
Publisher:	American Chemical Society
ISSN:	0002-7863
Date:	May 2011
Volume:	Vol.133
Number:	No.18
Page Range:	pp. 7180-7189
Identification Number:	10.1021/ja201135y
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	United States. Army Research Office, Robert A. Welch Foundation
Grant number:	W911NF-07-10409, F-1621
URI:	http://wrap.warwick.ac.uk/id/eprint/36949

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