Evolution of self-healing elastomers, from extrinsic to combined intrinsic mechanisms: a review

Abstract

The evolution of self-healing polymers has resulted in a myriad of healing designs that have given way to complex systems capable of supporting multiple cycles, among other features. This progression...

Design Principles of Interfacial Dynamic Bonds in Self‐Healing Materials: What are the Parameters?

“…Here, both entropy changes, as well as self-repair attributes, are affected by the flexibility of chains and chain rigidity that reflects in the glass transition temperature. [107][108][109] Recently, by adopting calorimetric, broadband dielectric measurements, and molecular mechanics based on the MM + force field, we studied the self-healing properties of SiO 2 NP (silica) reinforced natural rubber (NR) PNCs, directly correlating their self-healing ability at the micro/macroscopic to molecular level utilizing ionic and covalent cross-linkers. [110][111][112] Specific intermolecular interactions, such as ion-dipole and H-bonding interactions, proved to be the driving forces for the structured assembly leading to the NR-SiO 2 hetero-aggregate.…”

Self-Healing Polymer Nanocomposite Materials by Joule Effect

“…The extrinsic one is based on micro-capsular and micro-vascular systems that contain repairing agents [ 25 , 26 ]. These agents generally polymerize, repairing the damage [ 27 , 28 ]. The problem lies in the limited amount of repair agent [ 9 ], where upon its depletion, the material loses the ability to self-repair [ 14 ].…”

“…Self-healing materials can present many bond interactions, enclosed in two large groups: the so-called non-covalent and covalent interactions ( Figure 1 ). The former includes lower energy dynamic non-covalent bonds such as van der Waals interactions, π–π stacking, dipole–dipole interactions, hydrogen bonding, ionic interactions, metal–ligand coordination, and host–guest interactions [ 28 ]. The latter includes the highest energetic group, dynamic covalent bonds.…”

“…The latter includes the highest energetic group, dynamic covalent bonds. Although in this group there are many mechanisms, the most commons are Diels-Alder chemical interactions, transesterification reaction, disulfide bonds, imine bonds, boron-based bonds, and alkoxyamine [ 28 ]. From this group, the Diels-Alder (DA) reaction is highlighted for its thermally self-healing behavior [ 29 ].…”

“…To induce self-healing processes in polymer nanocomposites, polymer chains may diffuse into the damaged zone. For polymers, mobility of macromolecular chains occurs at temperatures above their glass transition [ 28 ], so that temperature plays an important role in polymer self-repairing [ 30 ]. It can be provided by thermal energy such as conventional heating in ovens [ 29 ], or by heating by microwaves and infrared irradiation [ 31 , 32 , 33 , 34 ].…”