Fully Biobased Catalyst-Free Vitrimer from Epoxidized Linseed Oil and Tartaric Acid Exhibiting Shape-Memory and Self-Healing Properties

Abstract

Bio-based vitrimers represent a promising route toward sustainable polymer networks that combine recyclability, repairability, and functional performance. In this work, a fully bio-based and catalyst-free vitrimer was developed from epoxidized linseed oil (ELO) and tartaric acid (TA), aiming to integrate vitrimer behavior with shape-memory and self-healing functionalities at moderate activation temperatures. The materials were prepared by curing ELO with TA at different epoxy: acid molar ratios, forming dynamic ester networks through epoxy–acid reactions. The systems were characterized by FTIR, DMA, swelling and gel content, rheology, stress relaxation, mechanical testing, shape-memory cycles, self-healing, and reprocessing experiments. Spectroscopic analysis confirmed epoxy consumption and ester formation. Increasing the epoxy: acid ratio increased gel content (83.3–93.5%), stiffness, and tensile strength, while reducing swelling, elongation at break, and impact strength. All compositions exhibited a glass transition near 50 °C. Stress-relaxation experiments revealed vitrimer behavior, with rapid relaxation above Tg and activation energies between 49 and 71 kJ·mol⁻¹. Excellent shape-memory performance was achieved, with shape fixity of ~ 90% and shape recovery between 95 and 97%. The materials also showed efficient self-healing and reprocessing, with visual crack closure and recovery of more than 90% of mechanical properties after reprocess. These results demonstrate that epoxidized linseed oil and tartaric acid form an efficient, sustainable vitrimer platform combining recyclability, self-healing, and shape-memory behavior, with potential applications in smart materials, recyclable, and self-repairing polymer systems.