Preparation Of Acylhydrazone Bond-based Thermosetting Resin And Study On Its Stimulation Response Performance

Covalent crosslinked polymers are widely used because of their excellent mechanical and thermal stability.However,due to the existence of irreversible covalent crosslinking network,thermosetting resins usually lack the ability of remodeling,reprocessing or recycling.Therefore,the thermosetting resin with Schiff base bond has been drawing more and more attention.This kind of resin has the characteristics of simple preparation,rapid response and so on.At present,most of the thermosetting resins containing Schiff base dynamic bond are prone to hydrolysis in water environment.Hydrazone dynamic bond and disulfide dynamic bond are more stable than imine bond.Therefore,the acylhydrazone bond was introduced into the structure of thermosetting resin in this experiment,and the thermosetting resin with acylhydrazone bond and disulfide bond was also prepared for the first time.This research has important theoretical and practical significance for the realization of the stimulation response of thermosetting resin.The conjugation effect of hydrazone bond makes it more stable than Schiff base bonds.In this paper,the trialdehyde monomer(TFMP)was prepared by simple molecular design.TFMP was reacted with two kinds of commercial hydrazides in a simple "one pot" method to prepare TFMP-Adipic dihydrazide thermosetting resin(TFMP-A)and TFMP-Isophthalic dihydrazide resin(TFMP-I)containing hydrazone bond.This method is simple and reliable without additional catalyst.The results showed that the resins in this experiment had excellent mechanical properties and the tensile strengths were around 68 MPa and 82 MPa,respectively.Meanwhile,the resin films also had good solvent resistance and thermal stability(Tg of the resins was around 200 ?).At the same time,due to the conjugation effect of dynamic bond of hydrazone,the hydrazone resins could maintain great stability in strong acid solution or under gamma irradiation and the resins would degrade in high temperature and low p H solution environment: under the condition of 1 mol/L sulfuric acid and 130 ? heating,the time required for the complete degradation of 0.02 g TFMP-A film and TFMP-I film was 12 min and 13 min respectively.In addition,based on the previous experience in the same field,it can be speculated that the hydrazide resin in this experiment has reprocessing performance and recyclability.On the basis of the study above,the dihydrazine dithiopropionate monomer with disulfide bond was designed and prepared.Based on the reaction between TFMP and dihydrazine dithiopropionate,the resin(TFMP-D)containing both hydrazone bond and disulfide bond was prepared in this paper.The optimal temperature rising program of TFMP-D resin was 40 ?-1 h,130 ?-1 h.Under these conditions,the tensile strength of the resin film could reach about 65.2 MPa.