Thermal-induced self-healing bio-based vitrimers: Shape memory, recyclability, degradation, and intrinsic flame retardancy

Authors: LI, WENBIN - Institute Of Chemical Industry Of Forest Products (ICIFP); XIAO, LAIHUI - University Of Birmingham; WANG, YIGANG - Institute Of Chemical Industry Of Forest Products (ICIFP); HUANG, JINRUI - Institute Of Chemical Industry Of Forest Products (ICIFP); Liu, Zengshe - Kevin; CHEN, JIE - Institute Of Chemical Industry Of Forest Products (ICIFP); NIE, XIAOAN - Institute Of Chemical Industry Of Forest Products (ICIFP)

Submitted to: Polymer Degradation and Stability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2022
Publication Date: 6/22/2022
Citation: Li, W., Xiao, L., Wang, Y., Huang, J., Liu, Z., Chen, J., Nie, X. 2022. Thermal-induced self-healing bio-based vitrimers: Shape memory, recyclability, degradation, and intrinsic flame retardancy. Polymer Degradation and Stability. 202. Article 110039. https://doi.org/10.1016/j.polymdegradstab.2022.110039.
DOI: https://doi.org/10.1016/j.polymdegradstab.2022.110039

Interpretive Summary: Plastic materials we use every day usually have deficiencies, for example, deformation (shape changing) under load, extremely flammable, or melts when exposed to heat. Because of these drawbacks, they have limited use in some applications and fields. In this research, we reported the development of new sustainable plastics with excellent flame retardancy and self-healing properties from renewable resources. The key to this technology is the combination of a natural compound and an ultrafast reaction chemistry to form network structured materials. This research may ultimately provide an efficient strategy for the synthesis of bio-based self-repairing flame retardant materials with rigid structure which contributes to the development of high-performance sustainable plastics.

Technical Abstract: The structure of epoxy resin determines its flammable property, non-reprocessing, unrecyclable, and nondegradable, which limits their application. Thus, a novel disulfide bond-containing dynamic covalent thiol-ene crosslinked epoxy vitrimers (TECEVs) as covalently adaptable networks were synthesized. Also, the structure-property relationship of polymeric compounds was investigated. The insoluble vitrimers networks demonstrated faster stress relaxation with 107 s at 200 °C, and obtained lower activation energy between 70.52 and 110.57 kJ·mol-1. In addition, the dynamic nature of the disulfide bond allowed the damaged TECEVs to be thermal-induced self-repairing and self-healing materials with efficiencies 100% at 160 °C. It was discovered that TECEVs can be reprocessed at 160 °C with the recovery of mechanical strength above 80% and be completely decomposed in an ethanol-acid catalyst solution. Moreover, typical TECEVs can function with excellent flame retardancy and illustrated a high limit oxygen index (LOI, 27.45–28.36%), and UL-94 V-0 rating was achieved. This work could provide an efficient strategy for the synthesis of “biobased self-repairing flame retardant” networks and contribute to the development of high-performance sustainable polymers.