Construction of biobased PEF/PTMC composite vitrimer with advanced performance in mechanical properties, reprocessability and foamability via catalyst-free method

In this work, we reported a facile approach for fabricating external catalyst-free poly (ethylene 2,5-furandicarboxylate)/poly (trimethylene carbonate) (PEF/PTMC) blend vitrimer through two-step reactive blending by the addition of 2,2-bis(hydroxymethyl) 2,2′,2″-nitrilotriethanol (BIS-TRIS) and N, N′-tetraglycidyldiaminodiphenyl methane (TGDDM) for the first time. This method breaks through the difficulties of the traditional preparation method of vitrimer materials that must require the addition of metal catalyst, thus realizing the concept of green chemistry. At the same time, it also breaks through the difficulty of poor compatibility in the traditional blend preparation methods. Swelling and FTIR tests confirmed the presence of the dynamic cross-linking structure consisting of PEF and PTMC chains, while rheological analysis shows that the formed cross-linked network in PEF/PTMC blend can significantly improve its melt strength and make it could be foamed by supercritical carbon dioxide. An expansion ratio about 10-fold and microcellular foam with a uniform cell morphology can be obtained for PEF/PTMC composite vitrimer when the PTMC content and the gel content was less than 20% and 50%, respectively. Moreover, PEFMC foams possess greater compressive strength than that of commercial PET foams, exhibiting excellent mechanical properties. TGA and tensile experiments revealed that PEF/PTMC composite vitrimer exhibited excellent mechanical performance and thermal stability. Meanwhile, PEF/PTMC composite vitrimer still maintain the ability of excellent reprocessability. This work provides a practical green method to guide the design of novel polymer blends with improved miscibility, mechanical properties and sustainability by a dynamic cross-linking network.