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Micro‐damage in materials could be repaired by endowing materials with self‐healing performance. Herein, an epoxy resin with excellent self‐healing performance grounded on thermo‐reversible Diels–Alder dynamic chemical reaction was developed. Results showed that the bending strength and adhesive behavior of epoxy resin were influenced dramatically upon treatment with various temperatures. More importantly, damages created in epoxy resin could be repaired completely after suitable heat treatments. What is more, the healed epoxy resin exhibited much higher bending strength and adhesive performance than the pristine one did. The materials could be damaged and then repaired repeatedly. Meanwhile, the as‐prepared self‐healing epoxy resin exhibited excellent thermal reversibility and controllable adhesion. The thermo‐adjusted self‐healing performance endowed epoxy resin with recyclable and reusable performance. Therefore, the research made it possible of recycling waste epoxy resins.

In this article, we present a facile method for the synthesis of an azo-group-bound silica (SiO 2 -azo) initiator. The azo groups were introduced onto the surface of silica (SiO 2 ) nanoparticles via facile condensation between 4,4 0 -azobis-4-cyanopentanoic acid and the alkylhydroxyl groups -immobilized on the SiO 2 nanoparticle surface under ambient conditions. The polystyrene (PS) chains were grafted onto the SiO 2 nanoparticle surface by in situ polymerization with the resulting SiO 2 -azo as an initiator, and then, the SiO 2 -PS composite was prepared. The syntheses and properties of the SiO 2 -azo initiator and the composite were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, gel permeation chromatography, and differential scanning calorimetry techniques. The results confirm that the SiO 2 -azo initiator and the composite were synthesized successfully. Styrene was polymerized with the initiation of SiO 2 -azo, and the resulting PS domain accounted for 48.6% of the total amount of composite.

This work presents a new method for synthesis of inorganic/organic hybrid nanoparticles via the in-situ polymerization by the use of the azo-groups bounded silica nanoparticles as a radical initiator and styrene as a model vinyl-monomer. The synthesis and the structure of silica/polystyrene (SiO 2 /PS), and the polymerization kinetics of the styrene initiated by the azo-groups bounded SiO 2 nanoparticles are studied with techniques such as FTIR, XPS, DSC, GPC, and TEM. Results show that the SiO 2 -g-PS nanoparticles are synthesized successfully, and the resulting hybrid nanoparticles have a core-shell structure with SiO 2 in the core and the polystyrene on the outside layer. The percentage of the grafted PS on the SiO 2 surface increases with the progress of the polymerization before 6 h, and the largest amount of the grafted PS reaches 33% of the silica nanoparticles. Consequently, the size of the nanoparticles increases ca. 20 nm upon the polystyrene grafting. The molecular weight of the grafted PS increases with the polymerization, and it has reached a much large value in the first several polymerization hours while it keeps a constant value approximately in the following polymerization process. Meanwhile, the polydispersity index of the grafted PS gradually increases with the progress of the polymerization. These phenomena agree with the theory of the traditional free radical polymerization very well.