Diels–Alder Cycloaddition‐Cycloreversion: A Powerful Combo in Materials Design

Abstract

Reactive polymers are increasingly becoming materials of wide interest because they offer solutions to challenges in biomolecular immobilization, drug‐delivery and enzyme modifications. The Diels–Alder (DA) cycloaddition and the retro Diels–Alder (rDA) cycloreversion reaction in combination enables synthesis of maleimide based reactive polymeric materials. Also, the DA cycloaddition offer a reagent‐free ‘click’ reaction to construct various macromolecular architectures. Furthermore, the thermally reversible nature of the DA adducts makes them attractive building blocks for the design of thermoreversible materials. A discussion of some of the author's own research work in this area is presented in this article within the context of recent reports in polymer chemistry employing this reaction combo.magnified image

Thermoreversibly Crosslinked Poly(ε‐caprolactone) as Recyclable Shape‐Memory Polymer Network

“…In comparison, physically crosslinked SMPs (PC-SMP, mainly TPUs [11][12][13] ) can be readily reprocessed but usually require several thermomechanical cycles to access optimized shape-memory properties (so-called training cycles). [1] By using thermoreversible Diels-Alder cycloaddition [14,15] to crosslink star-shaped poly(e-caprolactone), a polymer known to exhibit shape-memory properties when chemically- [16,17] or physically-crosslinked, [11][12][13] we will show here for the first time that a new class of SMP can be obtained that display at the same time the advantages of CC-SMP, i.e., outstanding fixity and recovery ratios with Figure S1.…”

Thermally reversible cross-linked poly(ether-urethane)s

“…The application of reversible Diels-Alder (rDA) chemistry to the dynamic covalent assembly of organic materials has been only recently explored [1][2][3][4]. The number of DA reactions that undergo dynamically reversible adduct formation under mild conditions is, however, limited and there is an increasing interest in expanding the set of dynamic covalent DA reactions [5][6][7][8].…”

Microwave-promoted synthesis of cyclic imides

“…[21][22][23][24][25] The maleimide moiety can be used as a versatile synthesis platform due to its Michael accepting [26][27][28][29] and dienophilic nature, as well as its dipolarophile characteristic in 1,3-dipolar cycloadditions. [30][31][32][33] A recent review shows the importance of maleimides as building blocks for the synthesis of polymers. 34 Substituted succinimides (3) such as ethosuximide, methosuximide or phensuximide, among others ( Figure 2), have strong anticonvulsant activity.…”