Silica-based Janus nanosheets for self-healing nanocomposite hydrogels

As functional nanocomposites, Janus nanomaterials can play an important role due to their asymmetric structure and different components on the same surface. In this manuscript, hollow silicon spheres (SiO2 JHs) with an asymmetric structure were prepared by an emulsion interfacial self-organized sol-gel process. Inspired by mussel chemistry, the exposed surfaces of the SiO2 JHs were modified chemically by polydopamine (PDA). 2-(3-(6Methyl-4-oxo-1,2,3,4-tetrahydropyrimidin-2-yl)ureido)ethyl methacrylate (MAUPy) containing multiple hydrogen bond groups were grafted to obtain SiO2@PDA/PMAUPy Janus Nanosheets (SiO2@PDA/PMAUPy JNs) by Pickering emulsion. The prepared SiO2@PDA/PMAUPy JNs were further applied to prepare nanocomposite self-healing hydrogels. As a result of the synergy of reversible non-covalent metal-ligand and hydrogen bonding, hydrogels with dual self-healing feature were successfully fabricated. The obtained hydrogels maintain preferable mechanical properties (strain of about 411.0% and stress of about 4.1 MPa) and excellent healing ratio (92.6%), which may have broad application prospects in smart flexible sensor and biomedical application.