pH响应均三嗪淀粉醚的合成及性能研究

pH响应均三嗪淀粉醚的合成及性能研究Synthesis and Properties of Novel pH-responsive s-triazine Starch EtherAbstractIn this study,based on acidic and alkaline responsiveness of tertiary amino and carboxylgroups,pH-responsive s-triazine tertiary amine starch ether and amphoteric starch weredesigned and synthesized by introduction of tertiary amino groups and carboxyl groups intostarch using s-triazine as a bridge linker.The synthetic conditions,properties of aqueoussolutions and applications of the products were studied in detail.It provided a new idea tosynthesize pH-responsive starch-based functional material,and developed high-performanceand high value-added starch-based material with potential applications.Firstly,etherifying agent 2,4-bis(dimethylamino)-6-chloro-[1,3,5]-triazine (BDAT)containing two tertiary amine was synthesized by nucleophilic substitution reaction betweendimethylamine and cyanuric chloride.The effect of reaction conditions on the yield of BDATwas thoroughly studied.The highest yield of the BDAT reached 94%.The structure of theproduct was confirmed by IR,H NMR,13C NMR and MS spectroscopy.Then,BDAT wasgrafted to starch to form a new tertiary amine starch ether2,4-bis(dimethylamino)-[1,3,5]-triazine-6-yl)-starch (BDATS)via etherification reaction.Themaximum degree of substitution (DS)and reaction efficiency (RE)were 1.01 and 68.0%,respectively.The structure of the starch derivatives was confirmed by IR and 13C NMRspectroscopy.BDATS demonstrated reversible pH responsiveness in aqueous solution.Solution properties of the obtained BDATS,such as transmittance,Zeta-potential,surfacetension and viscosity,were measured as a function of pH.The critical pH of the solutionshifted to a low pH by increasing DS of the BDATS.Amphoteric etherifying agent 2,4-diglycino-6-chloro-[1,3,5]-triazine (CDT)wassynthesized via nucleophilic substitution reaction between glycine and cyanuric chloride.Itsstructure was confirmed by IR,3C NMR and MS spectroscopy.A new amphoteric starchether 2,4-diglycino-[1,3,5]-triazine-6-yl)-starch (CDTS)was prepared via etherificationbetween starch and 2,4-diglycino-6-chloro-[1,3,5]-triazine.The maximum DS and RE were0.88 and 73.4%,respectively.The structure of the starch derivatives was confirmed by IR.The transmittance of CDTS solution showed the characteristic U-shaped distribution relativeto the pH.Phase transition can occur at and around the isoelectric point (IEP)of theampholytic polymers,leading to decrease of Zeta potential and solution transmittance.Furthermore,pH-responsive properties of the solution can be controlled by regulating DS ofCDTS.