The design of a green and renewable bio-based self-healing vitrimer has attracted extensive attention due to the increasing emphasis on an environment friendly society. However, it remains a challenge to design and fabricate a fully bio-based vitrimer with a room temperature self-healing ability without sacrificing the aqueous stability and mechanical performance. In this work, a dialdehyde monomer was designed and synthesized using vanillin, 2,5-furandicarboxylic acid, and succinic acid. A fully bio-based Schiff base vitrimer was prepared with the bio-based curing agent Priamine 1071 (FDV-1071 and SCV-1071). The synthetic process was simple under mild conditions at room temperature without any catalyst. The rigid polyphenyl and furan structure of the dialdehyde monomer endowed the vitrimer with reinforced mechanical performance, and the tensile strength and T_g of FDV-1071 reached 2.45 MPa and 25.14 °C, respectively. The fully bio-based vitrimer containing both an imine bond and an active ester bond showed excellent thermal reversibility and self-healing properties. FDV-1071 slices allowed multiple reprocessing cycles at 120 °C and 10 MPa and still retained the self-healing ability even at room temperature. In addition, the aliphatic chains of Priamine 1071 increased the hydrophobicity of the vitrimer, greatly enhancing the stability in the aqueous environment, and the degradability of the vitrimer was tunable by the introduction of an organic solvent.

Tissue adhesives based on polyamidoamine (PAMAM) dendrimer, grafted with UV-sensitive aryldiazirine (PAMAM-g-diazirine) are promising new candidates for light active adhesion on soft tissues. Diazirine carbene precursors form interfacial and intermolecular covalent crosslinks with tissues after UV light activation that requires no premixing or inclusion of free radical initiators. However, primary amines on the PAMAM dendrimer surface present a potential risk due to their cytotoxic and immunological effects. PAMAM-g-diazirine formulations with cationic pendant amines converted into neutral amide groups were evaluated. In vitro toxicity is reduced by an order of magnitude upon amine capping while retaining bioadhesive properties. The in vivo immunological response to PAMAM-g-diazirine formulations was found to be optimal in comparison to standard poly(lactic-co-glycolic acid) (PLGA) thin films.

It is a challenge to develop polyurea with high-performance and multifunctionality because the integration of functions often comes at the expense of mechanical properties. This work synthesized a novel diisocyanate with a pyrene side chain, followed by reacting with poly(propylene oxide) diamine to prepare polyurea elastomers (PPU-x). Herein, thanks to the strong π–π stacking effect between pyrene groups and the anchoring effect of the amino group, the maximum tensile strength of PPU-x reached 41.4 MPa. The large conjugate structure of pyrene groups also gave PPU-x outstanding fluorescence and UV shielding performance. More noteworthy is the fact that graphene can be well dispersed in PPU-x with such high polarity via π–π interactions, which caused the dielectric constant of graphene-modified PPU-x nanocomposites to be three times that of PPU-0.3. Furthermore, this nanocomposite was used to make a triboelectric nanogenerator. Under the action of 0.5 N, the output voltage can reach 80 V, which is expected to be used to monitor weak signals of the human body. This work opens up a new strategy for the development of high-performance polyurea and its graphene-modified multifunctional polyurea nanomaterials with wide potential applications.

Microwave irradiation is one of the most effective strategies to accelerate the curing of resin. However, the mechanism is still unclear. The debates mainly focus on how to quantitatively evaluate the ‘non-thermal’ effect of the microwave. In this work, the non-thermal effect on DGEBA with amine (D230) and anhydride (MHHPA) hardeners respectively was evaluated via an isothermal microwave curing reactor. The ‘thermal effect’ caused by the microwave was peeled off accurately. Iso-conversional kinetic analysis was performed based on the reaction extent from the real time FTIR spectrum, and the apparent activation energy (E_a) was calculated for the quantitative evaluation of the microwave non-thermal effect. The influence caused by the polarized functional groups, reaction temperature and the transition state were explored, and the microwave non-thermal effect on the mechanical performance of the cured thermosets was evaluated. Results indicated that the microwave non-thermal effect was able to reduce the E_a and accelerate the curing speed of epoxy resin. At the same time, the final curing extent was increased when the non-thermal effect of microwave was induced leading to enhanced mechanical and thermal performance.