Self-Healing, Reprocessable, and Degradable Bio-Based Epoxy Elastomer Bearing Aromatic Disulfide Bonds and Its Application in Strain Sensors

A dicarboxylic acids functional aromatic disulfide (DTSA) and a dimer aliphatic acid (DAA) were used to crosslink epoxidized soybean oil (ESO) to obtain a bio-based epoxy elastomer with comprehensive properties of toughness and stretchability. This work addresses some urgent needs for epoxy networks, such as recyclability, degradability, and mechanical properties. Ratios of permanent and dynamic crosslinks were tuned to yield epoxy elastomers with various characteristics. The bio-based epoxy elastomer in this work took advantages of dynamic aromatic disulfide bonds which can rapidly exchange even at room temperature without external stimuli. Therefore, the epoxy elastomer reported here presented almost quantitative self-healing efficiency and high recovery in terms of mechanical properties after being reprocessed for many times. Besides, incorporation of permanent chemical crosslinks with DAA caused low hysteresis, which made them suitable for fabricating sensitive and durable strain sensor against cyclic strain.