Self-healing unsaturated polyester sensor based on multiple hydrogen bonds

[Display omitted] •Unsaturated polyester was synthesized with biological matrix.•Highly efficient self-healing material with unique structural control and design.•Flexible sensor with excellent mechanical properties. Intelligent bio-based self-healing polymers are advanced and sustainable materials that are widely used in military, coatings and conductive materials. However, it is a challenging task to design unsaturated polyester materials with good stretching ability, efficient self-repair ability and sensitive sensing ability. In this paper, a class of bio-based unsaturated polyester is synthesized, and the functional self-repairing unsaturated polyester material is obtained through the control and design of its structure. Firstly, a flexible self-healing polyester crosslinking network (CPUBT-UPy) was prepared by introducing 2-urea-4[1H] pyrimidinone (UPy) into the unsaturated polyester chain through chain extension reaction and using polyethylene glycol (PEG) to regulate the structure and properties of unsaturated polyester. By adjusting the molar ratio of BDO and UPy, the elongation at break of the elastomer can reach 2020.94%, and the self-repair efficiency can reach 91.33%. After 5 repair cycles, the self-repair efficiency can still reach 79.01%. A flexible conductive material was prepared by the composite of CPUBT-UPy and 15% MWCNTs-NH2, and is further assembled into a universal flexible strain sensor, which showed excellent sensitivity to finger bending, speech and frowning. Finally, unsaturated polyesters also confer potential degradability on elastomers.