Facile Approach for the Preparation of Robust and Thermally Stable Silyl Ether Cross-Linked Poly(ethylene-vinyl acetate) Vitrimers

Vitrimers as an emerging class of dynamic polymer networks hold great promise for the development of sustainable thermosets. While the straightforward method to prepare vitrimers from commodity polymers is cost-competitive, most studies involved the synthesis of polymers with specific functional groups and/or crosslinkers. Herein, we demonstrated a simple and scalable approach to produce poly(ethylene-vinyl acetate) (EVA) vitrimers by direct cross-linking of an industrial EVA product with commercial bis[3-(trimethoxysilyl)propyl]amine using titanium(IV) butoxide as a catalyst through reactive blending. Incorporation of the thermally stable silyl ether cross-links into the network led to significantly enhanced thermal and mechanical properties. Compared to the original EVA, the resulting vitrimers showed up to 4 and 2 times improvement in Young's modulus and tensile strength, respectively. The creep resistance of the EVA vitrimer increased with the cross-linking density, and notably, EVA-V0.8 displayed a low permanent deformation of 1.2% at a high temperature of 180 degrees C, much higher than the normal service temperature. Moreover, the vitrimers displayed excellent reprocessability and recyclability, and the Young's modulus, tensile strength, and elongation at break of the EVA vitrimers were nearly identical even after four times of recycling.