Structure-Controlled Synthesis Of Hyperbranched Polymers With "Latent" Inimer Based On Diels-Alder Chemistry

Recent advances in synthetic chemistry and geometrical conception have promoted the development of topological polymer chemistry.Changes in the topology of polymers produce different physical,biological,and chemical properties with a wide range of potential applications.Hyperbranched polymers(HBPs),as an important topological structure,are widely used in drug carriers,nanomaterials technology,and molecular sensors due to their highly branched structure and significant properties such as enhanced solubility,decreased solution viscosity,and extensive terminal groups.Therefore,it is important to develop a universal synthesis method for hyperbranched polymers with controllable structures.In this thesis,a "latent" inimer with a furan-protected maleimide(FMI)group is prepared and used for the structure-controlled synthesis of HBPs by self-condensation vinyl polymerization(SCVP),which provides new ideas for the structure-controlled construction of hyperbranched topologies.The investigation details are shown as follows.(1)Synthesis of "latent" inimer and preparation of hyperbranched polymers.The "latent" inimer with the FMI group was synthesized from maleic anhydride,furan,ethanolamine,and 2-bromoisobutyryl bromide.Then the hyperbranched polymers were prepared by the SCVP of conventional polymerization monomer MMA and the "latent" inimer,which can undergo retro-Diels-Alder(r-DA)to give naked maleimide group under high temperature.The SCVP process and the hyperbranched structure were demonstrated by nuclear magnetic resonance(NMR),size exclusion chromatography(SEC),differential scanning calorimetry(DSC)and FT-IR spectra.(2)Structure-controlled synthesis of hyperbranched polymers.By changing the stereochemical structure of the FMI group in the "latent" inimer or the reaction temperature,the r-DA reaction rate can be regulated to influence the incorporation of the maleimide group into the polymer chain.Thus,the structure-controlled synthesis of hyperbranched polymers was realized.The molecular weight,molecular weight distribution,and branching degree of the hyperbranched polymers were characterized by NMR,DSC,SEC-MALLS-Visc-RI and FI-IR.(3)Preparation of complex hyperbranched topologies with "one-pot" strategy.During the process of SCVP polymerization between the "latent" inimer and MMA,the "onepot " construction of star-shape and longchain hyperbranched topologies was realized by us-in g programmable temperature strategy(programmable temperature strategy).The different hyperbranched topologies were characterized by NMR,SEC and DLS/SLS.