Preparation And Properties Of Vanillin-based Schiff Base Vitrimer

Thermosetting resin materials have been widely used because of their excellent properties.However,traditional thermosetting resins do not dissolve or melt after curing and crosslinking,which causes serious waste of material resources and environmental pollution.In recent years,using sustainable biomass materials to replace non-renewable petroleum-based materials has become a hot research topic.To a large extent,the above problems can be solved by using green and renewable bio-based resources to prepare vitrimer materials that can be reprocessed,degradable,and recycled.Bio-based Schiff base is one of the most commonly used vitrimer materials due to its mild reaction conditions and no need for a catalyst.In this paper,biological vanillin was used as the reaction raw material and two vanillin-based Schiff base vitrimer with different bio-based contents were prepared through different network structure designs.The research results obtained are as follows:1.Three vanillin aldehyde dialdehyde monomers were designed and reacted with ternary amine T403 respectively to prepare Vanillin-based Schiff base vitrimer(O-VDNET,M-VDNET,and P-VDNET).The effects of the isomer structure on the mechanical properties,thermal stability,degradation activity,and reprocessing performance of the polymer network were investigated.The results show that the P-VDNET cross-linked network has the best comprehensive performance among the three isomers.P-VDNET has the highest tensile strength and Tg,which are 50 MPa and 64.14 o C,respectively,due to its poor conformational freedom,shorter linear chain,and higher crosslinking density.In addition,the network structure contains both imine and ester bonds,which have multiple stimulus-response capabilities,realizing rapid degradation of Na OH in 1 M HCl/THF solution at room temperature and in aqueous solution at 90 o C,respectively.At the same time,imine bond encodes Schiff base vitrimer crosslinking network with thermal reversible properties and self-healing ability: has good reprocessing ability at 180 o C and10 MPa pressure.This study revealed the structure-activity relationship between the structure and properties of vanillin isomers and the response to multiple stimuli,providing basic data and guidance for the structural design of materials.2.In order to solve the problem that vanillin was the only source of bio-based material in the P-VDNET system and the content of bio-based was limited,two fully bio-based Schiff base vitrimer(FDV-1071,SCV-1071)were constructed.In this paper,vanillin was used to react with 2,5-furandiformyl chloride and succinyl chloride from biomass respectively to prepare a fully bio-based dialdehyde monomer,and then reacted with Priamine 1071 to prepare the fully bio-based Schiff base vitrimer,and the relationship between the network structure and performance was studied in detail.It is concluded that FDV-1071 has better thermal properties,thermal stability,thermal-mechanical properties,and mechanical properties because the furan ring structure in the FDV-1071 network has higher rigidity and crosslinking density than the flexible chain structure in the SCV-1071 network.The tensile strength and Tgof FDV-1071 are 2.5 MPa and 25.14 o C,respectively.Because the curing agent Priamine 1071 contains more long fat chains,the material has hydrophobic properties;Materials can degrade in mixed solutions of acids or bases containing organic solvents;The imine bond encodes the vitrimer with excellent thermal reversible properties and self-healing ability.The vitrimer can be reprocessed at 120 o C and 10 MPa many times,and the mechanical properties of the material can be maintained after circulation;Minor scratches on the surface of the material can be self-healing at room temperature.This provides new guidance for the preparation and research of fully bio-based materials.