Catalyst-free, sustainable epoxy vitrimers from epoxidized soybean oil and natural sugar alcohols

Vitrimers based on dynamic transesterification (DTE) are usually thought to highly rely the use of catalysts, for example, Lewis acids and tertiary amines to promote the bond exchange reaction, which bring additional concerns on human health and the environment. Herein, we report a family of fully bio-based epoxy vitrimers that rearrange their topologies via DTE in the absence of any catalyst. Specifically, epoxidized soybean oil (ESO) was efficiently cured by conjugated carboxylic groups formed in-situ through the ring-opening of maleic anhydride (MA) by sugar alcohols (SAs) in a one-pot and solvent-free manner to produce these vitrimers. Abundant -OH groups from SAs strongly enhanced mechanical properties the without hindering stress relaxation or re-processing of the vitrimers. Meanwhile, welding, crack-healing and shape editing at high temperatures was achieved. The vitrimer samples exhibited various recovery rates of tensile strength upon 3 times of mechanical recycling.