Room-Temperature Self-Healing Polyurea with High Puncture and Impact Resistances

Abstract

Polyureas are widely used as protective materials because they have good mechanical strength, toughness, and strain-rate-dependent behavior. However, the fast reaction between −NCO and the −NH2 component results in gelation in seconds, limiting their performance regulation and applications. In this study, we report a novel strategy to fabricate one-component polyurea with room-temperature self-healing, puncture resistance, and impact resistance. First, a latent curing agent was synthesized via the Schiff base reaction of an aliphatic diamine with isobutyraldehyde. Then, they were mixed directly with isocyanate. Such a mixture was uncured in storage without moisture, but it was cured once in contact with moisture in the application. So, it was called one-component polyurea. The polyurea exhibits room-temperature self-healing properties with a healing efficiency of up to 98%. It has puncture displacement as high as 15.1 cm by sharp objects. The polyurea also exhibits excellent impact resistance and dissipative energy capacity because it possesses strain-rate-dependent behavior. The polyurea can be integrated into Kevlar fabrics to form a flexible puncture-resistant composite and combined with carbon nanotubes to form flexible and wearable strain sensors. It is expected to find applications in intelligent soft materials, soft body armor, wearable flexible sensors, and other fields.