Shape Memory Supramolecular Polyurea with Adjustable Toughness and Ultrahigh Energy Density

As typical stimulus-responsive materials, shape memory polymers (SMPs) have potential for many advanced applications owing to their controllable and programmable shape-changing properties. However, the combination of high toughness and tailorable strength remains a challenge to overcome for SMPs. Here, we engineered meticulously a supramolecular structure with quadruple and double hydrogen bonding arrays to achieve shape memory polyurea elastomers with adjustable strength and toughness. The polyurea with a supramolecular structure had the highest tensile strength of 47 MPa and ultrahigh toughness up to 256 MJ m–3. Meanwhile, the polyurea was also adjustable to a small tensile strength of 0.87 MPa matching the tensile strength of biological soft tissue (≈1 MPa). The reversible hydrogen bonding arrays endowed polyurea with a shape memory effect as well as excellent self-healing properties. More importantly, the prestretched polyurea could raise a 500 g weight, which is over 3968 times its own mass, up to 18 mm, because of a high energy density of 75 MJ m–3, which was higher than the energy density of most SMPs (generally <1 MJ m–3).