A biomass-based Schiff base vitrimer with both excellent performance and multiple degradability

Abstract

A Schiff base cross-linked network is one of the most significant vitrimers, which has attracted extensive attention due to its excellent recyclable, degradable and malleable properties. However, the preparation of Schiff base polymers with an excellent mechanical property and multiple stimulus response performance still remains a challenge. In this work, three kinds of vanillin dialdehyde monomers (O-VD, M-VD and P-VD), isomers of each other, have been synthesized and cured with T403 to obtain the Schiff base cross-linked networks (O-VDNET, M-VDNET and P-VDNET). The polyphenyl ring structures endow the networks with good strength, and both the Schiff-base and ester groups give the networks multiple degradability. Among them, the para-position network, P-VDNET, possessed the best comprehensive properties: the T_ga obtained from DSC was 42.58 °C, T_gb obtained from DMA was 63.14 °C and the thermal stability of the network reached a high char yield of nearly 30% at 800 °C. Moreover, P-VDNET showed a tensile strength as high as around 50 MPa, and it can also be rapidly degraded in both acidic solution and NaOH aqueous solution due to the inherent dynamic imine bond and active esters. In particular, it achieves a monomer recovery at the molecular level after an acidic degradation process. Meanwhile, we compared the mechanical and thermomechanical properties of these three networks formed by o-, m-, and p-vanillin dialdehyde isomers, which provides a strategy for the structural design of vitrimer materials.