Lyu Jihong, Song Gyujin, Jung Hyocheol, Park Young Il, Lee Sang-Ho, Jeong Ji-Eun, Kim Jin Chul
Center for Specialty Chemicals, Division of Specialty and Bio-Based Chemicals Technology, Korea Research Institute of Chemical Technology (KRICT), Ulsan 44412, Republic of Korea.
Ulsan Advanced Energy Technology R&D Center, Korea Institute of Energy Research (KIER), Ulsan 44776, Republic of Korea.
ACS Appl Mater Interfaces. 2024 Jan 10;16(1):1511-1520. doi: 10.1021/acsami.3c15337. Epub 2023 Dec 21.
Given the substantial environmental challenge posed by global plastic waste, recycling technology for thermosetting polymers has become a huge research topic in the polymer industry. Covalent adaptive networks (CANs), which can reversibly dissociate and reconstruct their network structure, represent a key technology for the self-healing, reprocessing, and recycling of thermosetting polymers. In the present study, we introduce a new series of polyurethane CANs whose network structure can dissociate via the self-catalyzed formation of dithiolane from the CANs' polydisulfide linkages when the CANs are treated in ,-dimethylformamide (DMF) or dimethyl sulfoxide at 60 °C for 1 h. More interestingly, we found that this network dissociation even occurs in tetrahydrofuran-DMF solvent mixtures with low DMF concentrations. This feature enables a reduction in the use of high-boiling, toxic polar aprotic solvents. The dissociated network structure of the CANs was reconstructed under UV light at 365 nm with a high yield via ring-opening polydisulfide linkage formation from dithiolane pendant groups. These CAN films, which were prepared by a sequential organic synthesis and polymerization process, exhibited high thermal stability and good mechanical properties, recyclability, and self-healing performance. When lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt was added to the CAN films, the films exhibited a maximum ion conductivity of 7.48 × 10 S cm because of the contribution of the high concentration of the pendant ethylene carbonate group in the CANs. The ion-conducting CAN films also showed excellent recyclability and a self-healing performance.
鉴于全球塑料垃圾带来的巨大环境挑战，热固性聚合物的回收技术已成为聚合物行业的一个重大研究课题。共价自适应网络（CANs）能够可逆地解离并重构其网络结构，是热固性聚合物自我修复、再加工和回收利用的一项关键技术。在本研究中，我们引入了一系列新型聚氨酯CANs，当在60℃下于N，N-二甲基甲酰胺（DMF）或二甲基亚砜中处理1小时时，其网络结构可通过CANs的多硫键自催化形成二硫杂环戊烷而解离。更有趣的是，我们发现这种网络解离甚至在低DMF浓度的四氢呋喃-DMF溶剂混合物中也会发生。这一特性能够减少高沸点、有毒极性非质子溶剂的使用。CANs的解离网络结构在365nm紫外光下通过二硫杂环戊烷侧基形成开环多硫键以高产率进行重构。这些通过连续有机合成和聚合过程制备的CAN薄膜表现出高热稳定性、良好的机械性能、可回收性和自我修复性能。当向CAN薄膜中加入双（三氟甲磺酰）亚胺锂（LiTFSI）盐时，由于CANs中高浓度侧基碳酸亚乙酯基团的贡献，薄膜表现出最大离子电导率为7.48×10⁻⁴ S cm⁻¹。离子导电CAN薄膜还表现出优异的可回收性和自我修复性能。
