Studies On The Synthesis And Functionalization Of The Hyperbranched Polymers By Superelectrophilic Arylation

In the1940s, a series of theoretical works on the molecular size distribution in three dimensional polymers were published by Flory. These works laid the theoretical foundation of highly branched polymers. Since then, numerous types of highly branched polymers have been synthesized. Among them hyperbranched polymers is an important subclass. Until the late1980s, accompanying the focus shift from strength to functionality in polymer science and technology, hyperbranched polymers have now become one of the hottest fields, due to their unique properties, such as highly reactive, numerous terminal groups and wide range of potential applications.In this thesis, a series of hyperbranched polymers have been prepared based on the superelectrophilic reaction, including the hyperbranched polymer analogous to the dendrimer, the hyperbranched polymer with enzyme activity and the hyperbranched polyacenaphthenequinones prepared via a facile A2+B3approach.A fully branched hyperbranched polymer with a focal point has been prepared by superelectrophilic polycondensation of (AB2) monomer5-bromo-l-(4-(4-phenoxybenzoyl)benzyl)indoline-2,3-dione with a core with six functional arms (B’6)5,5’,5"-((benzenetricarbonyltris(benzene-4,1-diyl))tris(oxy))tris(acenaphthylene-1,2-dione) in a slow addition manner. To reduce the chance of the homopolymerization of the monomers, the acenaphthenequinone group with higher reactivity was chosen as B’for the core and the isatin group with lower reactivity as B in the monomer. The obtained polymers were characterized by1H NMR,13C NMR, TGA and GPC. The thermodecomposition temperature of the polymer could reach400℃. The NMR spectra indicated the100%branching degree of the hyperbranched polymers and the successful introduction of the core. The proportions of the terminal/dendritic groups in the hyperbranched polymers with low monomer/core feeding ratio were evaluated through NMR and GPC data respectively. Through comparison and analysis it was revealed that most of the hyperbranched polymers possessed quasi-spherical structures. The molecular weights of the hyperbranched polymers increased almost linearly with the feeding ratio of the monomer to the core and the polydispersities of the polymers were greatly influenced by the monomer concentration. At the optimal monomer concentration, the main parts of the GPC curves were symmetric and narrow. Although there were traces of faint shoulder, the molecular weight distributions of the polymers were still acceptable. The branching degree of100%, controllable molecular weights, narrow distribution, plus the quasi-spherical and hierarchical architectures of cores, dendritic and terminal units made the fully branched polymer with a focal point analogous to dendrimers in all respects, offering a highly efficient option to fabricate dendrimer substitutes.A novel glutathione peroxidase (GPx) mimic has been prepared by incorporation of a selenium-based catalytic unit into the focal point of a fully-branched hyperbranched polymer. Firstly, an AB2monomer consisting of isatin and an electron rich aromatic moiety was polycondensed in the presence of5-nitroisatin as a core reagent, resulting in a polymer with100%degree of branching. The latter was coup led to the catalytically active moiety, Br(CH2)5SeSe(CH2)5Br, by nucleophilic substitution of the bromides by the residual amide groups of the incorporated nitroisatin core. The obtained polymer has demonstrated prominent GPx activity as desired, which could be attributed to the hydrophobic, densely branched and core-shell structure of the polymer surrounding the catalytic center.A series of hyperbranched polyacenaphthenequinones has been prepared by superelectrophilic aromatic substitution of (substituted) acenaphthenequinone and l,3,5-tris-(4-phenoxybenzoyl) benzene via a facile A2+B3approach. Because of the strongly increased reactivity of the second A functionality, gelation was efficiently avoided during the polymerization. The structure of the resulting polymer was characterized by NMR spectroscopy and gel permeation chromatography. Further modification of the hyperbranched polyacenaphthenequinone was explored both on the acenaphthenequinone and aromatic moieties. Moreover, the polymer modified through sulfonation was investigated as a water-soluble acid catalyst for the degradation of biomass resources, and the catalytic hydrolysis result showed that the LA from cellulose has a yield of30.5mol%.