Internal catalysis for dynamic covalent chemistry applications and polymer science

Abstract

In this review, we provide a concise analysis of internal catalysis as an attractive design principle to combine chemical robustness with reactivity in dynamic covalent chemistry applications and a material context.

Polybenzoxazines: a sustainable platform for the design of fast responsive and catalyst-free vitrimers based on trans-esterification exchanges

“…This behavior is in adequation with one of the first observations made by Leibler et al about the relationship between the amount of catalyst and the short τ* of vitrimers 6. Moreover, the catalytic effect is more pronounced thanks to the close position of the NR 3 groups regarding the -OH groups, in agreement with the NGP theory recently disclosed by Du Prez et al11 and illustrated in Scheme 1.…”

“…They were called poly(PEG-DPA-mea 75 /fa 25 ), poly(PEG-DPA-mea 50 /fa 50 ), poly(PEG-DPA-mea 25 /fa 75 ), corresponding to materials where 75%, 50% and 25% of mea was substituted by 75%, 50% and 25% of fa, respectively. NMR revealed that they correspond to materials containing a ratio of N/COO/OH equal to 2/1/1.38, 2/ 1/0.91 or 2/1/0.5, in respect to the order given in the sentence above (Table 1, rows [10][11][12]. The details of the preparation and characterization of all the materials can be found in the ESI (Fig.…”

“…5,6 In the present work, the catalytic effect originates from the neighboring group participation (NGP) of the NR 3 groups in the mechanism of the TER (Scheme 1), in a similar fashion than described by Du Prez et al in a recent review. 11 The activation of the -OH groups is promoted by intramolecular hydrogen bonding with the lone electron pair carried by the nitrogen atoms. While the energy of the H-O bonds decreased owing to the N-H interaction, the atom of oxygen became nucleophilic enough to attack the electrophilic center of the carbonyl bond, allowing the TER to occur.…”

“…At higher temperatures, they display the fluidity and the reprocessing ability of a thermoplastic. [5][6][7] The different strategies and methodologies conceived to design performant vitrimers can be found in the excellent reviews published by Du Prez et al, [8][9][10][11] and Hillmyer and Dichtel. 12 Among these strategies, the dynamic transesterification reaction (TER) occurring between ester bonds and hydroxyl (-OH) groups has been reported as the most representative chemistry for driving vitrimer behaviors.…”

Synthesis of polymers containing vicinal tricarbonyl moiety and construction of reversible crosslinking–decrosslinking polymer system

“…The dissociable nature of the covalent bonds endows the networked polymers with chemical recyclability 1–5 . The re‐workability and self‐repairing ability of polymer networks are also enabled using dynamic covalent bonds 6–10 . Equilibrium polymerization of heterocyclic monomers such as cyclic carbonates and bicycloorthoesters is also a useful tool for the construction of chemical recycling systems 11,12 …”