Self-healing Reconfigurable Thermosets Constructed By Thiol-terminated Hyperbranched Polymers And Their Functional Applications

Thermosetting polymers with plasticity can be prepared by introducing dynamic covalent bonds（such as disulfide bonds,imine exchange,transesterification,boronic ester or boroxine exchange,Diels-Alder bonds etc.）into polymer crosslinking networks.At present,the self-healing and reprocessing capability of thermosetting polymers containing CANs are mutually restricted with its mechanical properties.CANs sacrifice the rigidity and crosslinking density of the materials,which results in reducing the capacity of bearing the loads of the materials,dimensional stability and chemical resistance,limiting the applications of CANs in thermosetting polymerization.Based on this,we constructed a reconfigurable thiol-terminated hyperbranched polymer,and explored its applications in degradable thermosetting resin/carbon fiber composites and photoluminescent self-healing thermosetting materials,respectively.The main research contents are as follows:（1）Dynamic crosslinking polyurea carbon fiber composites were prepared by using thiol-terminated hyperbranched polymer（THBP）and isocyanate-terminated hyperbranched polymer（IHP）.The tensile strength,tensile modulus,interlaminar shear strength（ILSS）of 12%IHP/THBP/HDI/TCF composites prepared by THBP,IHP and thiol-functionalized carbon fiber fabric（TCF）can reach 700.5 MPa,44.0GPa and 68.4 MPa,respectively.The fracture mode of polyurea carbon fiber composites changes from interlayer resin fracture to multilayer fracture when IHP is added.This is due to the unique hyperbranched topology and intramolecular rigid structure of IHP can increase the crosslinking density of the interphase region,and at the same time,some cavities are introduced to enhance its load transfer efficiency,thus improving the interfacial properties of polyurea carbon fiber composites.IHP/THBP/HDI/TCF composites can be selectively degraded into ATP monomer,THBP and carbon fiber fabric through hexahydro-s-triazine structure degradation and nucleophilic catalysis dissociative mechanism of hindered urea bonds.Compared with the original IHP/THBP/HDI/TCF composites,the retention rates of the tensile properties,interlamellar shear properties and dynamic mechanical properties of the regenerated carbon fiber composites obtained by nucleophilic catalysis dissociative mechanism of hindered urea bonds are more than 90%,86%and 87%,respectively.（2）P-Cu²⁺polythiourethane composites with excellent mechanical properties,photoluminescence and plasticity were prepared by introducing Cu²⁺coordination bonds.The introduction of Cu²⁺can increase crosslinking density（ρ）,prolong relaxation time（τ*）and increase activation energy（E_a）of the dynamic exchange reaction,thus ensuring the dimensional stability of the composites.After repeated processing for three times,the retention rates of the tensile strength,elongation at break,tensile toughness and glass transition temperature（T_g）of P-Cu²⁺are 100%,89%,89%and 98%,respectively.The fluorescent anti-counterfeiting films prepared with P-Cu²⁺can achieve re-encrypted and rewritten in the range of 25～180 ^oC,which is expected to be used in the fields of high temperature resistant and rewritable anti-counterfeiting films.