A high-strength flexible transparent reprocessable polyurea film based on dual dynamic noncovalent interactions

To address the issues that waste of resources and environmental pollution caused by discarded materials, dynamic bonds are widely introduced into polymers to endow them with reprocess ability. However, there are some obvious issues in existing research such as poor toughness, low fracture elongation, and inability for repeated reprocessing of materials. Considering above problems, this study introduces dense hydrogen bonding and cation–π interactions into the polyurea system, and develops a high-performance transparent film based on dual dynamic non-covalent interactions, which enables the film to be reprocessed. Through the synergy of the dual non-covalent networks, the film exhibits a high tensile strength of 79.6 ± 3.9 MPa and good hardness (pencil hardness of 4H, elastic modulus of 2.69 GPa). It can effectively resist the scratching of copper brush and maintain more than 97% of its initial mechanical strength after being reprocessed five times. In addition, the film has good adhesion to various substrates, as well as high flexibility (0.5 mm) and excellent optical properties (high light transmission of 91.1% and low haze of 0.94%). This study proposes a novel approach to enable polymer materials to be reprocessed and demonstrates the preparation of a film with great potential in optical protection and wearable devices.