Surface-Initiated Metal-Free Photoinduced ATRP of 4-Vinylpyridine from SiO2 via Visible Light Photocatalysis for Self-Healing Hydrogels

Robust and self-healable nanocomposite hydrogels were realized by the encapsulation of components of photoinduced electron transfer–atom transfer radical polymerization (PET–ATRP) into surface-modified silica nanoparticles (SiO2). The prepared SiO2@P4VP was in the form of self-healing nanocomposite hydrogels, where 4-vinylpyridine (4VP) was polymerized through PET–ATRP with organic photocatalyst Rhodamine B. The modified nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. The nanocomposite hydrogels can be healed rapidly and autonomously without any stimulation at ambient temperature. Specifically, the nanocomposite hydrogels have a tensile strength of about 2.90 MPa, which recovered to 77.0% after 12 h, and an elongation at break of about 730%. These self-healing hydrogels with cheap raw material, possessing better strength and self-healing performance, will have broad prospects.