Highly tough, self-healable and transparent polyurea elastomers via bulk polymerization

Many newly developed polyurethane elastomers (PUEs) often rely on organic solvents for dissolving specific components such as chain extenders, in order to achieve improved mechanical toughness, self-healing capability, etc. However, solvents complicate the synthesis and raise multiple problems relating to post-processing, greatly limiting the application of self-healing PUEs. Herein, a novel bulk polymerization routine for synthesizing polyurea elastomers is designed by specific chain extender well-dissolved in the prepolymer, as well as moisture-assisted curing without using any solvent. The synergy of aromatic disulfide dynamic chemistry and urea bondage endowed the resultant elastomers with high toughness, ultrafast (∼1 s) and efficient (up to 98.6%) self-healing capability at various temperatures (∼-23°C), resistance to puncture, colorless and transparent nature approaching the standards of photovoltaic glass. The work offers a facile, adjustable and efficient routine for constructing high-performance polyurea elastomers, which have big promise not only in the field of material science, but also in the industrial production and application of polyurethanes.