The Construction Of High Performance Indolyl Epoxy Resin Based On Cation-π And Performance Studies

Epoxy resin materials have excellent chemical stability and mechanical properties,and are widely used in aerospace,machinery and electronic equipment,with broad prospects and huge commercial value.However,unmodified epoxy resins tend to be brittle,have poor anti-cracking properties,are easily aged and difficult to recycle,which restrict their further development.To address the problems of traditional epoxy resin materials,this thesis uses cation-πas the driving force to construct an epoxy network with dynamic cross-linking between molecular chains,and a new class of high-performance resins with high strength,recyclability,and multifunctionality that are difficult to obtain by conventional methods has been developed.In Chapter 2,a linear epoxy resin（EPI）was synthesized from E51 epoxy resin and tryptamine,then by adding magnesium tert-butoxide to prepare high-energy Indole-Mg-Indole cation-π（In-Mg-In）crosslinking indole-based epoxy resin.In-Mg-In as a dynamic crosslinking point not only has not only has the characteristics of dynamic bonds,but also has a large binding force（2.1 n N）,and ultra-high bond energy（311 k J/mol）.By adjusting the crosslinking density,when the content of magnesium tert-butoxide is 10%of the molar weight of tryptamine,CEPI-10 has the best mechanical properties.Compared with EPI,the tensile strength is increased from 62 MPa to 108 MPa,and the elongation at break is increased from 5.4%to 21.1%,which solves the problem that the strength and toughness of rigid materials are difficult to greatly improve at the same time.Meanwhile,CEPI-10 can also be recycled by both thermal processing and dissolution recovery.In addition,CEPI-10has the characteristics of self-warning and self-healing,and the repair and bonding of the material can be realized in a simple way.In Chapter 3,indole-based epoxy resin(PIN^（x）)cross-linked by interlocking cation-πare prepared from bisphenol A epoxy resins,cystamine and sodium tryptophan.As a dynamic cross-linking point,the interlocking cation-πhas a larger bond energy（111.68 k J/mol）than the traditional cation-π.By adjusting the cross-linking density,when the content of sodium tryptophan is 50%of the molar weight of cystamine,the mechanical properties of PIN^（1/2）the most excellent.The tensile strength is increased from 30.0 MPa to 62.2 MPa,and the elongation at break is increased from 4.4%to 9.8%.Meanwhile,PIN^（1/2）can also be recycled by thermal processing recovery,and the recovered CEPI-10 has the similiar performance as the original.The water-responsive properties of PIN^（1/2）were investigated,The results show that the interlocking cation-πin the material aggregates with each other as hydrophilic chain segments to form a hydrophilic microphase inside the material,which is highly sensitive to water molecules and can rapidly undergo gradient swelling and generate large stresses.The PIN^（1/2）of the rigid framework can swell and bend within 4 s,and generate a bending force equivalent to 107 times its own weight.A set of horizontal short-distance transportation platform was designed and developed by utilizing the water absorption properties of PIN^（1/2）,showing the potential application value of this high-performance epoxy resin.