A polyurethane integrating self-healing, anti-aging and controlled degradation for durable and eco-friendly E-skin

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-04, Vol.410, p.128363, Article 128363
• Main Authors: Li, Fenglong, Xu, Zifa, Hu, Han, Kong, Zhengyang, Chen, Chao, Tian, Ying, Zhang, Wenwu, Bin Ying, Wu, Zhang, Ruoyu, Zhu, Jin
• Format: Article
• Language: English
• Subjects: Anti-aging; Controlled degradation; E-skin; Polyurethane; Self-healing
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.128363

The hybrid polydiols composed of high and low crystalline polyesters were used as the degradable soft segments for desirable polyurethane. Moreover, the dynamic disulfide bond was introduced to simultaneously endow the polyurethane with self-healing and anti-aging properties. Consequently, the polyurethane integrated room temperature self-healing, anti-aging and controlled degradation capacities. [Display omitted] •The self-healing and anti-aging could be simultaneously realized by disulfide bonds.•Degradable soft segments protected by hard segments lead to controlled degradation.•Self-healing, anti-aging and controlled degradation are integrated in a polyurethane. Two of the very important demands for the elastic matrix of electronic skin (E-skin) are durability and degradability, which ensure the stable performance in daily life and green end of the E-skin. Unfortunately, these two requirements are usually incompatible. Here, we proposed the idea of controlled degradation and synthesized a polyurethane, AL-PU-4, to solve such challenge. High crystalline hydroxy-terminated poly (1,4-butylene adipate) (HTPBA) and low crystalline polycaprolactone diol (PCL diol) were mixed and used as the degradable soft segment. The dynamic disulfide bond was chosen as the chain extender, which could simultaneously endow the polyurethane with anti-aging and self-healing properties. The AL-PU-4 didn’t show significant loss in mechanical and molecular weight after 12 days of accelerated aging experiment, which equaled to 12 months of daily use, and it owned a fast room temperature self-healing speed of 1.31 μm/min. With the steric protection of the hard segment, the degradation of ester bonds in HTPBA and PCL diol segments was seriously retarded under enzymatic and low pH conditions. Only when the pH reached 14, the ‘lock’ on degradation was opened. The above functionalities were also verified in an E-skin demo, which could response the external pressure quickly and show high stability in cyclic test.