Computational study of the transamination reaction in vinylogous acyls: Paving the way to design vitrimers with controlled exchange kinetics

Abstract

One of the key points in the design of vitrimers is controlling the associative exchange kinetics. One common chemistry used in vitrimers is based on the dynamic amine exchange reaction of vinylogous acyl compounds in presence of free amine. Understanding the reaction mechanism is essential to assist the optimization of the reaction conditions as well as the molecular structure of the reactant compounds in the pursuit of new materials. In this work, a computational study has been performed to explore different reaction mechanisms in neutral, acidic and in basic conditions or in the presence of Lewis acids, as well as the effect of chemical modifications in the exchange reaction. The results reveal that the formation of hydrogen bonds are a key feature and that the vinylogous urea improves the transamination compared to vinylogous urethane. The esteric hindrance of the amino group in the vinylogous compound also plays an important role. Finally, the nature of the free amine can improve the reactivity by equilibrating two contrary effects: the basicity favors the nucleophilic attack and the conjugated acidity favors the protonation. The findings of this theoretical work shed light in the design of new vitrimers with controlled exchange kinetics by chemical modifications.

Structure and Dynamics of Associative Exchange Dynamic Polymer Networks

“…Likewise, an apparent activation energy E a was calculated by the temperature dependence of relaxation time λ , that is, E a = 76.6 kJ/mol, which was closed to the value calculated from (82.8 kJ/mol in Figure d). The apparent activation energies of the dynamic vinylogous urethane exchange reaction (from the terminal relaxation time) are comparable with other vinylogous urethane vitrimers calculated from experiments or computational studies (∼55–102 kJ/mol). ,,,− …”

Self‐healing polymers for aviation applications and their impact on circular economy

“…[109][110][111] It is important to note that polyamide generally known as aramid generates N 2 O during their manufacturing process which has about 300 times the greenhouse effect as that of CO 2 . This calls for a much-needed enhanced lifecycle of polyamide using much promising self-healing abilities reported as transamidation chemistry by researchers 112 S C H E M E 2 Dynamic transesterification reaction of TEP and anhydride (adopted from reference 93 ). and polycondensation yields favorable mechanical properties and self-healing capabilities in SH-cPAs, while also offering a straightforward and precisely adjustable approach to the synthesis of furfurylamine-N,N-bis(methyl propionate) (FA-BMP) and furan pendent groups (pFU-Pas).…”

“…It is important to note that polyamide generally known as aramid generates N 2 O during their manufacturing process which has about 300 times the greenhouse effect as that of CO 2 . This calls for a much‐needed enhanced lifecycle of polyamide using much promising self‐healing abilities reported as transamidation chemistry by researchers 112 Hamzehlou et al have presented a computational study on the transamination reaction in vinylogous acryls. Although this is a theoretical study but can be useful to design polyamide‐based vitrimers with necessary aviation applications.…”

Closed-Loop Recyclable Vinylogous Carbamothioate-Based Covalent Adaptable Networks

“…Transamination of vinylogous acyls is a widely used dynamic chemical reaction that is catalyst-free. − As shown in Figure B, a series of vinylogous acyl compounds with different acyl groups (X), such as vinylogous urethane (X = O), vinylogous urea (X = NH), and vinylogous amide (X = CH 2 ), have been employed to fabricate CANs with tunable dynamicity and thus reprocessability and self-healing ability. − High refractive index polymers (HRIPs) have been widely used in optical and optoelectronic devices due to their lightweight and easy processability compared to inorganic materials. , While for modern optical and optoelectronic materials, rational design of recyclable and self-healable HRIPs toward sustainability has become prevalent in recent years. , Incorporation of highly polarizable atoms or groups such as aromatic rings and sulfur-containing groups into polymers can profitably enhance their refractive indices. Motivated by this, we envisage that replacing the acyl substituent X with sulfur (S) is expectable to fabricate a novel CAN, integrating advantages of good flexibility of carbon–sulfur (C–S) containing macromolecular chains, as well as great dynamicity and high molar refractivity of elemental sulfur containing moieties. − …”