Biobased catalyst-free covalent adaptable networks based on CF₃-activated synergistic aza-Michael exchange and transesterification

Abstract

Recently, fluorine neighboring group activation emerged as a new way of promoting acid-epoxy reaction and transesterification in vitrimer materials. Pursuing this idea, the effect of a CF3 group on aza-Michael...

Self‐Healable, Malleable, Ecofriendly Recyclable and Robust Polyimine Thermosets Derived from Trifluoromethyl Diphenoxybenzene Backbones

“…In detail, the tensile strength of the recycled materials can be recovered by 108.4 % after the first reprocessing, and 124.2 % after the second reprocessing, which is ascribed to more exchange reaction of imine bonds and an increase of cross‐linking density by hot pressing experiment [36] . Recently, fluorine group activation emerged as a new approach to promoting transesterification in vitrimer materials reported by Ladmiral and coworkers [27e] . Thus, the introduction of −CF 3 in our work may also accelerate the exchange of dynamic imine bonds and improve its recyclability.…”

“…FPIV‐100 specimens were separately put into different solvents, including methanol (MeOH), ethanol (EtOH), ethyl acetate (EtOAc), ethylene glycol (EG), 1‐Methyl‐2‐pyrrolidinone (NMP), tetrahydrofuran (THF), and H 2 O at room temperature for 24 h. Sheets of dynamic thermosets remained unaltered after immersed in chemical agents of MeOH, EtOH, and EG at room temperature, indicating strong solvent resistance. However, the FPIV‐100 film completely dissolved in THF and NMP 24 h later, which was caused by the imine exchange reactions disrupting the cross‐linking and fluorinated groups enlarging free volume leading to high exchange rate [27e] . This property can be applied in the recovery of fiber or carbon reinforced composites.…”

Thia-Michael Reaction: The Route to Promising Covalent Adaptable Networks

“…Accordingly, it has been demonstrated at the molecular and material scale that the introduction of a CF 3 group in α-position of the ester enabled to highly improve the aza-Michael exchange rate. Indeed, the inductive effects of the CF 3 group activates both the dissociation of the β-amino ester and the Michael addition of another amine onto the acceptor [ 92 ].…”

Sustainable polyester vitrimer capable of fast self-healing and multiple shape-programming via efficient synthesis and configuration processing

“…25 Qiu et al synthesized a PET-based vitrimer through a post-curing method, which required 10 h. 23 However, the long-time reaction at high temperatures will consume large amounts of energy, and the addition of an external catalyst is harmful to both end-users and the environment. 26 Besides, due to the fact that the covalent adaptable networks of vitrimers are hard to flow, they are usually restricted to non-continuous processing, which is inefficient. 27 Concerning energy-saving and environmental-friendly purposes, it is challenging to efficiently synthesize vitrimers with fast relaxation time via green and external-catalyst-free methods.…”