Addressing the recyclability of existing sulfur-containing polymers and developing new sulfur-containing polymers with inherent recyclability for the future material economy are both in line with the United Nations Sustainable Development Goals. Due to the presence of 1,2-dithiolane moiety, natural thioctic acid (TA) tends to undergo ring-opening polymerization upon thermal- or UV-initiation, and the resulting polyTA is capable of inverse ring-closing depolymerization to regenerate oligomers and cyclic monomers. Polymers constructed from TA provide a solution for the development of sustainable materials. However, their inherent weak networks make them difficult to use in engineering materials featuring high durability and mechanical robustness. Therefore, the development of alternative strategies to endow polyTA with advanced mechanical and dynamic performance still remains a big challenge.
Recently, Prof. Jun Hu from Beijing Advanced Innovation Center for Soft Matter Science and Engineering, in collaboration with Prof. Min-Hui Li from Chimie ParisTech, PSL University, synthesized an autocatalytic dual-dynamic CANs from diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate (DGEDC), TA, and bis(p-aminocyclohexyl)methane (PACM) in one-pot. The resulting DGEDC/TA/PACM thermosets exhibit good mechanical and thermal properties (Tg of 145°C, Td5% of 289°C, tensile strength of 70 MPa, Young’s modulus of 2.25 GPa), higher than previous poly(thioctic acid)-based materials. Due to topological network rearrangements induced by the exchange of disulfide bonds and tertiary amine-catalyzed transesterification reactions, they can be easily reshaped and repaired. Furthermore, they can be degraded mildly and upcycled into polyurethane foams by in-situ foaming. This strategy of autocatalytic dual-dynamic CANs will inspire the development of practical applications of poly(thioctic acid).
The first author is Yaning Ma, a PhD student in the Center for Soft Matter Science and Engineering. Prof. Jun Hu and Prof. Min-Hui Li are the co-corresponding authors. This work has been supported by Beijing Natural Science Foundation and the Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences.
Yaning Ma, Zihan Zhao, Zhiran Zheng, Jiawei Li, Min-Hui Li* and Jun Hu*. High-performance poly(thioctic acid)-based thermosets featuring upcycling ability for in-situ foaming enabled by dual-dynamic networks. Matter 2024, https://doi.org/10.1016/j.matt.2024.08.008.
