基于多重动态共价键的环氧类玻璃网络的制备与性能

以三羟甲基丙烷三缩水甘油醚(TTE)为基体, 2,2′-(1,4-亚苯基)-双[4-硫醇1,3,2-二氧杂戊烷](BDB)和3,3-二硫代二丙酸(DTDPA)为交联剂, 通过环氧-巯基“点击”反应和环氧-羧酸酯化反应, 制备了基于多重动态共价键(硼酸酯键、 二硫键和酯键)的环氧类玻璃网络. 利用红外光谱和拉曼光谱对其结构进行了表征, 结果表明， 环氧类玻璃中不仅存在硼酸酯键、 二硫键和酯键, 还存在可逆氢键, 并且大量氢键的存在能提高环氧类玻璃的交联度. 对所得环氧网络的热稳定性、 热机械性能和力学性能进行了测试, 并对基于多重动态共价键环氧网络进行了自修复、 焊接、 形状记忆和再加工能力测试. 结果表明, 在80 ℃下可实现网络的完全自修复、 再加工与焊接, 且焊接后样品的力学性能(拉伸强度)恢复率在80%以上, 具有优异的功能性.

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

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 ℃ 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.