Fabrication and Properties of Epoxy Vitrimer Based on Multiply Dynamic Covalent Bonds

摘要

Traditional epoxy networks were wildly applied in composites,adhesives,coatings,electronic packaging and insulating materials,due to their excellent properties and stable network structure. However,once epoxy networks are formed,they cannot be reprocessed. When epoxy networks are damaged during the serving time,they cannot be self-healed. Epoxy vitrimers networks with dynamic reversible covalent bonds can reorganized their network typology under external stimuli,contributing to network reprocessing and self-healing. Currently,most epoxy vitrimers show a high temperature for reprocessing and self-healing,consuming high energy. Herein,the epoxy vitrimers with tri-dynamic covalent bonds(boronic ester bond,disulfide bond and ester bond)were fabricated by epoxy-thiol "click" reaction and epoxy-carboxylic acid reaction. The structures of the prepared epoxy vitrimers were characterized by Fourier transform Infrared spectrometer (FTIR) and Raman spectroscopy, and hydrogen bonds were found in the prepared epoxy vitrimers contributing to improvement of crosslink density. Meanwhile,the thermal stability, thermo-mechanical properties and mechanical properties of the prepared epoxy vitrimers were investigated by thermogravimetry (TG),dynamic mechanical analysis (DMA) and tensile testing. Furthermore,self-healing, welding, shape memory and reprocessing capabilities of the prepared epoxy vitrimers were researched. The results display that at 80 degrees C the scratches on the prepared epoxy vitrimers can be fully recovered and the welding recovery of tensile strength of the prepared epoxy vitrimers is >80%, indicating excellent functionality.

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