Catalyst-free self-healing fully bio-based vitrimers derived from tung oil: Strong mechanical properties, shape memory, and recyclability

• Published in: Industrial crops and products 2021-11, Vol.171, p.113978, Article 113978
• Main Authors: Xu, Ya-zhou, Fu, Pan, Dai, Song-lin, Zhang, Hai-bo, Bi, Liang-wu, Jiang, Jian-xin, Chen, Yu-xiang
• Format: Article
• Language: English
• Subjects: Bio-based vitrimers; Catalyst-free; High mechanical properties; Recyclable adhesives; Tung oil
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2021.113978

•TOTGE with terminal epoxy groups was prepared using tung oil.•Catalyst-free self-healing vitrimers were prepared using TOTGE and citric acid.•The vitrimers exhibited high properties due to the introduction of terminal epoxy groups.•Vitrimers can complete network rearrangement with autocatalysis of −OH groups.•The vitrimers exhibited self-healing, shape memory and reprocessing. Vegetable oil-based vitrimers are innovative renewable polymers that show promising applications. However, their applications are limited by their poor mechanical properties and the need for the use of a catalyst in their preparation. In this study, the renewable tung oil underwent the methyl esterification reaction, Diels-Alder reaction, and epoxidation reaction to obtain TOTGE with terminal epoxy groups. TOTGE was cured with citric acid (CA) to obtain catalyst-free, self-healing, high mechanical strength fully bio-based TOTGE–CA vitrimers. Due to the high reactivity of their terminal epoxy groups, the vitrimer networks have a high density of crosslinks, and thus show good thermal stability and mechanical properties. The curing agent CA introduces a large number of hydroxyl (−OH) groups into the vitrimers and these form abundant hydrogen (H) bonds. The −OH groups in the vitrimers act as a catalyst, allowing topological network rearrangement of the materials in the absence of an external catalyst. Due to their dynamic ester and H bonds, the vitrimers exhibit good self-healing, recyclability, and shape memory properties, making them promising candidates for use as repairable and recyclable adhesives.