Synthesis Of Hydrophilic Hyperbranchedgraft-hyperbranched Copolymers And Their Applications In The Preparation Of Nanoparticles

In this dissertation,hydrophilic hyperbranched-graft-hyperbranched copolymer HPEI-g-HPG bearing hyperbranched polyethyleneimine(HPEI)core and hyperbranched polyglycidol(HPG)shell was synthesized.The synthesis,purification and intrinstic fluorescene of as-prepared copolymers were studied.Besides,the copolymers' applications in preparing semiconductor nanocrystals and gold nanoparticles were also studied.The details were as follows:1.HPEI was firstly modified by glycidol to get HPEI-OH with plenty hydroxyl end groups.Then HPEI-OH was used as macroinitiator of the anionic ring-opening polymerization of glycidol to get HPEI-g-HPG copolymers.The reaction conditions,including temperature,deprotonation rato,quantity of solvent and monomer dropping speed were optimized.Copolymer with different thickness of HPG shell were synthesized by changing the feed ratio of monomer and macroinitiator under optimized conditions.An acidification method was utilized to purify products in order to get rid of HPG homopolymers.A series of characterizations including 1H-NMR,13C-NMR,FTIR and GPC were used to fully characterize as-prepared copolymers.The mechanism and influences of copolymers' intrinstic fluorescence were also studied,and the oxydate of tertiary amine groups were regarded as the key factor of the polymers' PL properties.2.The as-prepared HPEI-g-HPGx copolymers were used as templates to stabilize semiconductor nanocrystals(QDs)in water.Water-soluble Cd S QDs were prepared with HPEI-g-HPGx as templates.The size and PL properties of QDs could be controlled by adjusting the temperature,nucleation time,Cd/S ratio,and N/S ratio during QDs preparation process.It's clear that when the N/S ratio was fixed,copolymer with a thicker HPG shell would be able to make the as-prepared QDs more stable and better in PL properties.The as-prepared Cd S QDs were used to detect metal ions and small molecules with thiols.It's found that HPEI-g-HPGx stabilized Cd S QDs were capable of detecting Hg2+ and L-cysteine with a LOD of 1.50×10-8 mol/L and 1.32×10-5 mol/L,respectively.Moreover,the ion selectivity of QDs became better as the shell of the polymer template became thicker.The asprepared QDs were used in the detection of Hg2+ in real water samples and Lcysteine in solutions of multiple amino acids,a relatively high recovery of target analytes was reached.Moreover,as-prepared Cd S QDs can also be used as effective photocatalysts in the degradation of methylene blue.3.HPEI-g-HPGx copolymers were used as stabilizer as well as reducer to prepared water-soluble Au NPs in situ.Experiments had discovered that stable Au NPs with small particle size could be prepared by adjusting the temperature,p H,shell thickness and quantity of polymer during preparation pocess.The as-preapared polymer stabilized Au NPs were compound with Fe3O4 NPs and used as heterogeneous catalysts in the reduction of p-nitrophenol.It's found that the shell of the copolymer could effectively protect the Au NPs from aggregation.