Research On Preraration And Properties Of Polyethylene Glycol(PEG)-poly(vinyl Carbazole)(PVK) Co-polymers

As an evergreen tree in polymer science,block copolymers are widely studied due to their special properties.Poly(vinyl carbazole)(PVK)is one of famous polymer semiconductors,which is a good hole transporting material and widely applied in optoelectronics.N-vinyl carbazole(NVK)is copolymerized with other functional monomers to form PVK-based block copolymers,which can entrust PVK with new properties and applications.In this thesis,the reversible addition-fragmentation chain transfer(RAFT)radical copolymerization was applied to obtain copolymers by using polyethylene glycol(PEG)RAFT agent.NVK was copolymerized with 2-((8-hydroxyquinoline-5-yl)methoxy)ethyl methacrylate(HQHEMA)and N-(2-methacryloyloxyethyl)-4-(N'-methyl-piperazine-1-yl)-1,8-naphthalimide(MMPN),respectively.And then,a series of amphiphilic block copolymers,PEG-b-PVK-co-PHQHEMA,PEG-b-PVK-co-Alq3 and PEG-b-PVK-co-PMMPN were successfully synthesized.The chemical structures and properties of these copolymers were characterized by Fourier transform infrared(FT-IR)spectroscopy,proton nuclear magnetic resonance(1H NMR)spectroscopy,high temperature gel permeation chromatography(GPC),ultraviolet-visible(UV-Vis)absorption spectra,photoluminescence(PL)spectra and thermogravimetric analysis(TGA).(1)Two monomers,HQHEMA and MMPN,were synthesized.Macro-RAFT agent(PEG-DDAT)was synthesized with methoxypolyethylene glycols and S-1-Dodecyl-S'-(a,a'-dimethyl-?"-aceticacid)trithiocarbonate(DDAT)via an esterification.The chemical structures of the monomers and RAFT agents were characterized by the 1H NMR and FT-IR spectra and the molecular weight of PEG-DD AT was calculated from the 1H NMR spectra.(2)The polymerization condition was optimized by adjusting polymerization temperature,feed ratio and feed type.A sires of copolymers(PEG-b-PVK-co-PHQHEMA)were synthesized via the RAFT radical polymerization and characterized by 1H NMR,GPC and FT-IR spectra,the mole ratios of the HQHEMA unit to the NVK unit in the copolymers were detected by 1H NMR spectra.The average molecule weights obtained from the GPC,1H NMR spectra and yields were compared and analyzed.(3)PEG-b-PVK-co-Alq3 was synthesized by the chelation of Pr-i-O-Alq2 and PEG-b-PVK-co-PHQHEMA.The chemical bonds between the aluminum and oxygen atoms were detected by the FT-IR spectra,in which the intensity of the characterized absorption peak was increased with the HQHEMA unit in the copolymers.The TGA results indicated that the decomposition temperatures of the copolymers were higher than 330?.The copolymer showed the different solubility in ethanol and dichloromethane(DCM),in which the conformations of the copolymer chains were different,and then,the different optical properties were observed.(4)PEG-b-PVK-co-PMMPN was synthesized from the NVK and MMPN monomers via the RAFT radical polymerization.The chemical structure of the copolymer was characterized by the 1H NMR,GPC and FT-IR spectra.The average numbers of the NVK and MMPN units in the copolymer were calculated according to the 1H NMR results.The PL intensity of the naphthalimide units was enhanced for excitation at 320 nm due to the resonance energy transfer from PVK to naphthalimides.The selectivity of the copolymer to Cu2+ was found in the THF solutions by researching the effects of pH value and metal ion on the optical properties of PEG-b-PVK-co-PMMPN.The aggregation of the copolymer lead to the increase of the energy transfer efficiency from PVK to naphthalimides in H2O.As a result,the enhanced PL intensity of naphthalimide was observed,but its selectivity towards metal ions was lost.