Utilizing the “Dangling Group Effect” Caused by the Cross-Linked Network Topology Transformation to Prepare High-Performance and Deformable Resins and Composites
Ji Zhou, Zhuodong Liu, Zhengguang Heng, Haoruo Zhang, Junliang He, Ying Ge, Yang Chen, Huawei Zou, Mei Liang
Abstract
It is attractive and realistic to construct deformable, recyclable, and high-performance adaptive structural materials. In this paper, a novel method was presented to improve the deformability of traditional epoxy resins by a topological design at the molecular level. Conformational transformation of cross-linked networks is facilitated by grafting rigid side groups onto the backbone, which can also be achieved in multicomponent epoxy resins with low side group concentration. The conformational evolution of the side groups enables resins to achieve multiple enhancements in the modulus, strength, and deformability of thermoset materials and was simulated by molecular dynamics. The property of group motion and free volume is further investigated by broad-band dielectric spectroscopy and positron annihilation lifetime spectroscopy. The dangling groups provide a possibility for the conformational changes in the network while retaining the advantages of high mechanical performance. This method offers further processing possibilities of thermoset materials and its composites, which will prove to be of great value in the near future.