The copper‐catalyzed azide/alkyne cycloaddition reaction (CuAAC) has emerged as the most useful “click” chemistry. Polymer science has profited enormously from CuAAC by its simplicity, ease, scope, applicability and efficiency. Basic principles of the CuAAC are reviewed with a focus on homogeneous and heterogeneous catalysts, ligands, anchimeric assistance, and basic chemical principles. Recent developments of ligand design and acceleration are discussed.

Carbon fiber-reinforced polymer (CFRP) composites are used in a variety of applications such as aircraft, automobiles, body armors, and the sports sector owing to their ultra-strong and lightweight characteristics. However, the incorporation of an untreated pristine carbon fiber surface leads to a weak interfacial interaction with the polymeric matrix, thus triggering catastrophic failure of the composite material. Graphene oxide, a 2D-macromolecule consisting of several polar functional groups such as hydroxyl, carboxyl, and carbonyl on the basal planes and edges, tends to increase the surface area and has thus been applied between the fiber and matrix, helping to improve CFRP properties. Herein, we condense different routes of functionalization of GO nanosheets and their incorporation onto a fiber surface or in a carbon fiber-reinforced epoxy matrix, helping to improve the interfacial adhesion between the fiber and matrix, and thus allowing effective stress transfer and energy absorption. The improvement of the interfacial adhesion between the fiber and carbon fiber-reinforced epoxy matrix is due to the peculiar structure of GO nanoparticles composed of polar groups, especially on the edges of the nanosheets, able to provide strong interaction with the hosting cured epoxy matrix, and the “core” part similar to the structure of CFs, and hence able to establish strong π-π interactions with the reinforcing CFs. The article also covers the effect of functionalized graphene oxide incorporation on the mechanical, thermal, electrical, and viscoelastic properties of composite materials reinforced with carbon fibers.

The article covers the outstanding features of fiber-reinforced vitrimer composites, including their reprocessing, recycling and self-healing properties.

Reversible Hydrogen Bonds (RHB) have been explored to confer self-healing function to multifunctional nanocomposites. This study has been carried out through a sequence of different steps. Hydrogen bonding moieties, with the intrinsic ability to simultaneously perform the functions of both hydrogen donors and acceptors, have been covalently attached to the walls of carbon nanotubes. The epoxy matrix has been modified to adapt the formulation for hosting self-healing mechanisms. It has been toughened with different percentages of rubber phase covalently linked to the epoxy precursor. The most performant matrix, from the mechanical point of view, has been chosen for the incorporation of MWCNTs. Self-healing performance and electrical conductivities have been studied. The comparison of data related to the properties of nanocomposites containing incorporated functionalized and nonfunctionalized MWCNTs has been performed. The values of the electrical conductivity of the self-healing nanocomposites, containing 2.0% by weight of functionalized multiwalled carbon nanotubes (MWCNTs), range between 6.76 × 10⁻³ S/m and 3.77 × 10⁻² S/m, depending on the nature of the functional group. Curing degrees, glass transition temperatures, and storage moduli of the formulated multifunctional nanocomposites prove their potential for application as functional structural materials.

Catalyst free disulfide exchange promoted epoxy/PDMS/GO-based self-healing vitrimeric material is reported, where efficiency of healing is extended through the presence of graphene, whereas PDMS is useful to enhance the toughness of the vitrimers.

This review article provides an overview of the research and applications of soft self-healing polymers and their nanocomposites. A number of concepts based on physical and chemical interactions have been explored to create dynamic and reversible gel and elastomer networks, each strategy presenting its own advantages and drawbacks. Physical interactions include supramolecular interactions, ionic bonding, hydrophobic interactions, and multiple intermolecular interactions. Such networks do not require external stimulus and are capable of multiple self-healing cycles. They are generally characterized by a rapid but limited healing efficiency. The addition of nanofillers enhances the mechanical strength of the soft networks as in conventional gels and elastomers, and do not compromise the network healing dynamics. In certain cases, nanofillers moreover trigger the healing process through e.g., multi-complexation processes between each component. Chemical interactions include Diels-Alder reactions and disulphide, imine, boronate ester, or acylhydrazones bonding, and are usually triggered with an external stimulus. The resulting healing is efficient, leading to good mechanical properties, but is generally slow at ambient temperatures, and dynamic chemical interactions are only reversible at higher temperatures. Conductive nanofillers were reported to speed up the healing process in such systems owing to their energy absorption properties. The challenges with nanofillers remain their functionalization and dispersion within the self-healing formulations. Soft self-healing gels and nanocomposites find applications in engineering such as coatings, sensors, actuators and soft robotics, and in the bio-medical field, including drug delivery, adhesives, tissue engineering and wound healing.