*Article* **Preparation and Properties of Self-Healing Waterborne Polyurethane Based on Dynamic Disulfide Bond**

**Gongbo Ye and Tao Jiang \***

Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, School of Materials Science and Engineering, Hubei University, Wuhan 430062, China; 2015011113000048@stu.hubu.edu.cn **\*** Correspondence: jiangtao@hubu.edu.cn

**Abstract:** A self-healing waterborne polyurethane (WPU) materials containing dynamic disulfide (SS) bond was prepared by introducing SS bond into polymer materials. The zeta potential revealed that all the synthesized WPU emulsions displayed excellent stability, and the particle size of them was about 100 nm. The characteristic peaks of N-H and S-S in urethane were verified by FTIR, and the chemical environment of all elements were confirmed by the XPS test. Furthermore, the tensile strength, self-healing process and self-healing efficiency of the materials were quantitatively evaluated by tensile measurements. The results showed that the self-healing efficiency could reach 96.14% when the sample was heat treated at 70 ◦C for 4 h. In addition, the material also showed a good reprocessing performance, and the tensile strength of the reprocessed film was 3.39 MPa.

**Keywords:** waterborne polyurethane; self-healing; dynamic disulfide bond

**Citation:** Ye, G.; Jiang, T. Preparation and Properties of Self-Healing Waterborne Polyurethane Based on Dynamic Disulfide Bond. *Polymers* **2021**, *13*, 2936. https://doi.org/ 10.3390/polym13172936

Academic Editors: Wei Wu, Hao-Yang Mi, Chongxing Huang, Hui Zhao and Tao Liu

Received: 11 August 2021 Accepted: 26 August 2021 Published: 31 August 2021

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