Preparation And Application Of Novel Copolymers With Both Dendritic Core And Shell

In this dissertation, on the basis of the hyperbranched polyethylenimine (HPEI)having a large number of amino groups, series of novel hyperbranched copolymersand supramolecular complexes with both dendritic core and shell were prepared.They were applied in the fields of guest encapsulation and synthesis of goldnanoparticles (AuNPs) with catalytic activity. The detail was as follows:1. The2,2-bis(hydroxymethyl)propionic acid (BHP)-based generation1dendronwith two palmitate tails or octanoate tails (D1-C16and D1-C8) and thegeneration2dendron with four palmitate tails (D2-C16) were synthesizedthrough the acylation reaction between BHP and palmitoyl chloride oroctoylchloride. The coupling of D1-C16, D1-C8or D2-C16with HPEI through theamidation reaction resulted in novel organo-soluble amphiphilic hyperbranchedcopolymers bearing a HPEI core and a dendritic D1-C16shell, dendritic D1-C8shell or dendritic D2-C16shell. The structure of the obtained copolymers and thedendrons was verified through Fourier transform infrared,1H NMR,13C NMR,mass spectrum and elemental analysis.2. These novel amphiphilic hyperbranched copolymers could be used asnanocarriers to efficiently accommodate the hydrophilic guests, including MethylOrange, Congo Red and Direct Blue15, into the hydrophilic amidated HPEI core.Each nanocarrier with a branched shell could accommodate a much highernumber of guests than the corresponding nanocarriers with linear shells, whichindicated that the dendritic structure of the shell played a key role in significantlyenhancing the encapsulation capacity of the nanocarriers.3. These novel amphiphilic hyperbranched copolymers could be used as templateand stabilizer to prepare organo-soluble AuNPs. The obtained small-sized AuNPscould be used as efficient catalysts for the biphasic catalytic reduction of4-nitrophenol by NaBH4. The stabilizers with a dendritic shell endowed theAuNPs catalyst with a higher performance than the corresponding stabilizerswith a linear shell, including:(1) a higher catalytic rate;(2) the ability to berecovered and reused more times;(3) a maximal turnover number of around23000, which is unprecedented in the catalytic reduction of4-nitrophenol.4. The noncovalent interaction of the amino groups of HPEI with the carboxylicacid group of D1-C16, D1-C8or D2-C16resulted in the novel supramolecular complexes with hydrophilic HPEI as core and hydrophobic D1-C16, D1-C8orD2-C16as shell. These supramolecular complexes could be used as nanocarriersto efficiently accommodate the hydrophilic anionic guests. Compared with thecorresponding nanocarriers with linear shell, those with dendritic shell showedbig advantages, such as higher encapsulation capacity, better resistance to theemulsion, high encapsulation capacity using a less amount of polymer and lesshydrophobic chains.5. A series of novel water-soluble hyperbranched copolymers were preparedthrough the anionic ring-opening polymerization of glycidol using differentmolecular-weight HPEI as the macroinitiator. The polymerization condition andpurification method were optimized. Furthermore, these novel amphiphilichyperbranched copolymers could be used as template and stabilizer to preparewater-soluble AuNPs.