Biobased, reprocessable and weldable epoxy vitrimers from epoxidized soybean oil

Biobased polymers prepared from vegetable oils such as epoxidized soybean oil (ESO) cannot be reprocessed or recycled due to the permanent crosslink structure. Herein, we report ESO derived vitrimers (ESOVs) synthesized by catalyst-free curing of ESO with 4, 4'-dithiodiphenylamine (APD) as a curing agent. The crosslink density controlled by curing time affect the mechanical properties of ESOV strongly. The tensile strength increased and elongation at break decreased gradually with increasing crosslink density of ESOV. The dynamic disulfide linkages of APD imparted the ESOV with excellent reprocessability and weldability via network topology rearrangement as a result of exchange reaction of disulfide bonds. The mechanical properties, gel fraction and chemical structure of ESOV almost remained unchanged after repeatedly cutting and compression molding for several times. The mechanical properties of ESOV were also recovered completely when two broken parts of ESOV were welded together. This study provides a facile and promising strategy to design novel functional materials from sustainable vegetable oils.