Disulfide‐centered poly(methyl acrylates): Four different stimuli to cleave a polymer. Issue 13 (20th April 2018)

• Record Type: Journal Article
• Authors: Fritze, Urs F.; Craig, Stephen L.; von Delius, Max
• Is Part Of: Journal of polymer science. Volume 56:Issue 13(2018)
• Page Start: 1404
• Page End: 1411
• Publication Date: 2018-04-20
• Subjects: cleavage reactions -- disulfides -- disulfide exchange -- mechanochemistry -- polymers -- poly(methyl acrylate) -- responsive materials; 547
• DOI: 10.1002/pola.29021
• Languages: English
• ISSNs: 0887-624X

Abstract

ABSTRACT: A series of poly(methyl acrylates) incorporating a disulfide center was subjected to four different stimuli to cleave the SS bond, as the weakest member of the chain. Four polymers with molecular weights in the range of 25–93 kDa were synthesized via Cu‐based atom transfer radical polymerization starting from a difunctionalized disulfide‐containing initiator. In tetrahydrofuran, the labile disulfide center was cleaved directly by mechanical force generated by ultrasound irradiation, whereas in chloroform, competing cleavage was also triggered by radical species that were generated by non‐mechanical sonolysis. A reductive cleavage was observed upon treatment with reducing agent, and a clean reversal of the cleavage via oxidation could be obtained if the terminal bromide was first removed via hydrogenolysis. This modified polymer allowed studies on a fourth strategy for the cleavage of the disulfide, namely, dynamic covalent exchange reactions with a fluorine labeled small molecule. While partially based on established protocols, this comparative study underscores the versatility of the disulfide bond for applications in stimuli‐responsive and adaptive materials. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2018, 56, 1404–1411 Abstract : The synthesis of a series of well‐defined polymers with a labile disulfide bond incorporated at the center of the chain and the cleavage of this bond under the influence of four different stimuli is described. An irreversible mechano‐ or sonochemical cleavage is observed due to ultrasound irradiation, whereas a reversible cleavage is observed under reductive and dynamic covalent exchange conditions. This comparative study is relevant for future applications of disulfide bonds in stimuli‐responsive and adaptive materials.