Dual Cross-linking of Epoxidized Linseed Oil with Combined Aliphatic/Aromatic Diacids Containing Dynamic S-S Bonds Generating Recyclable Thermosets

ACS Appl Bio Mater. 2020 Nov 16;3(11):7550-7561. doi: 10.1021/acsabm.0c00788. Epub 2020 Oct 16.

Abstract

The end-of-life of thermoset materials is a real issue that confronts our society, and the strategy of introducing dynamic reversible bonds can be a sustainable solution to overcome this problem. This study shows an efficient way to produce biobased and recyclable thermosets, for a circular use. To reduce the production costs linked to energy and duration, an improved curing process is proposed by combining aromatic and aliphatic diacid hardeners containing dynamic S-S bonds. The work demonstrates the increased reactivity of epoxidized vegetable oil reacted with the two diacids. The structural evolutions during the exchange reactions that allow the recyclability were followed by Fourier transformed-infrared and nuclear magnetic resonance spectroscopies, high-performance liquid chromatography, and mass spectroscopy. The curing process was studied by differential scanning calorimetry and kinetic study.

Keywords: aliphatic and aromatic diacids; curing reactivity; dual crosslinked network; dynamic disulfide exchange; epoxidized linseed oil thermosets; recyclable biobased thermosets.