Thermally Self-Healable Titanium Dioxide/Polyurethane Nanocomposites with Recoverable Mechanical and Dielectric Properties

Dielectric materials with self-healing property after the occurrence of detrimental events such as tearing or scratch are highly desired, which guarantees reliability and lifetime of the electric and electronic systems. Here, a self-healing covalently bonded titanium dioxide/polyurethane (TiO 2 /PU) nanocomposite with enhanced dielectric constant was prepared by in-situ polymerization based upon Diels-Alder reaction. The PU prepolymer was prepared from TiO 2 , poly(tetramethylene glycol) and 4,4-diphenylmethane diisocyanate. Then the linking between the prepolymer and Diels-Alder adducts of bifunctional maleimide blocked by furfuryl alcohol was carried out. The in-situ polymerization method allows the TiO 2 filler, the PU polymer matrix, and the DA healing portion to be tightly connected, resulting in a stable nanocomposite system. Due to the reversibility of covalent bonds, the TiO 2 /PU nanocomposites exhibited thermal self-healing properties after being cut. The dielectric constant and loss, mechanical properties can be effectively restored to their original state after damage.