Imine or Secondary Amine-Derived Degradable Polyaminal: Low-Cost Matrix Resin with High Performance
Yibo Shen, Ningdi Xu, Yonas Abate Adraro, Baolong Wang, Yingying Liu, Weihao Yuan, Xirong Xu, Yudong Huang, Zhen Hu
Abstract
In recent years, much effort has focused on the development of degradable thermosets; however, high cost and relatively low performance have become serious barriers to their practical applications. In this work, degradable thermosets based on imine/secondary amine dynamic bonds were prepared by amine aldehyde condensation. Specifically, terephthaldehyde and various diamines were used as monomers, and triethylenetetramine was selected as a novel cross-linker to prepare the degradable polyaminal. Because of the −NH2 and −NH–CH2–CH2–NH– groups in triethylenetetramine, a hybrid imine/imidazolidine cross-linking structure was obtained. Thanks to the rigid ring structure of imidazolidine, the polyaminal represents higher cross-linking density and mechanical properties compared with common thermosets based on Schiff base. Importantly, the present strategy reduced the preparation cost by ∼60% due to the usage of a quite low-priced cross-linker. The results showed that the obtained degradable polyaminal exhibits superior properties, Tg (120–150 °C), Td (249–277 °C), and tensile strength (52–64 MPa). Moreover, the polyaminal/carbon fiber composite could be completely degraded under mild acidic conditions within 1 h, leading to a rapid and nondestructive recycling of valuable fiber. This study is believed to offer an alternate strategy to set up a green framework for high-performance degradable thermosets that can potentially be used in commercial and industrial production.