Poly （methyl methacrylate） （PMMA） brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization （SI-ATRP）. Energy disperse spectroscopy （EDS） and atomic force microsco...Poly （methyl methacrylate） （PMMA） brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization （SI-ATRP）. Energy disperse spectroscopy （EDS） and atomic force microscopy （AFM） confirmed that PMMA brushes were successfully prepared on the silicon wafers, and the surface became more hydrophobic according to the contact angle of 69~. It is found that CuCI/1, 1, 4, 7, 10, 10-hexamethyl triethylenetetramine （HMTETA） system is more suitable than CuBr/N, N, N′, N″, N′″-pentamethyl diethylenetriamine （PMDETA） system to control the free radical polymerization of MMA in solution. Nevertheless, better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuC1/HMTETA due to higher activity and better reversibility of the former system.展开更多
An efficient route to macrocyclic polymers via “click” cyclization was presented.The α-bromine and ω-alkyne PMMA were prepared using the standard ATRP technique,initiated with propargyl 2-bromoisobutyrate,Cu(Ⅰ)Br...An efficient route to macrocyclic polymers via “click” cyclization was presented.The α-bromine and ω-alkyne PMMA were prepared using the standard ATRP technique,initiated with propargyl 2-bromoisobutyrate,Cu(Ⅰ)Br and N,N,N’,N″,N-pentamethyldiethylenetriamine(PMDETA).Azidation of the terminal bromine was followed in DMF with sodium azide,and α-azide,ω-alkyne PMMA precursor was obtained.Then the “click” cylcization of precursor between terminal azide and alkyne was carried out under the catalysis of CuBr/PMDETA,during the course of the reaction,a pseudo-high dilution technique was utilized to ensure the favored intramolecular cylcization.The nearly complete cylcization has been confirmed by a combination of IR,1H NMR and GPC analysis,and cyclo-PMMA with an Mn of 15000,PDI of 1.38 was obtained.展开更多
A novel hydroxy-capped comb-like block polymer, poly[poly(ethylene glycol)](HCPEG), was prepared via atom transfer radical polymerization(ATRP) of α-methylacryloyl-ω-hydroxyl-poly(ethylene glycol). The polymerizatio...A novel hydroxy-capped comb-like block polymer, poly[poly(ethylene glycol)](HCPEG), was prepared via atom transfer radical polymerization(ATRP) of α-methylacryloyl-ω-hydroxyl-poly(ethylene glycol). The polymerization kinetics of the PHPEGMA was studied by gel permeation chromatography and 1H NMR. The semilogarithmic plot of monomer conversion vs. reaction time increases linearly before the conversion is up to more than 70% and the number-average molecular weights(M_n) by GPC increased linearly with increase of the monomer conversion up to 100%, while the polydispersity index remained fairly narrow with M_w/M_n<1.2.展开更多
A new approach to the synthesis of dendrimer-like star polymer,[(PMMA)2PSt]4,was presented via the combination of atom transfer radical polymerization(ATRP) and ckick chemistry.Firstly four-arm bromine-terminated poly...A new approach to the synthesis of dendrimer-like star polymer,[(PMMA)2PSt]4,was presented via the combination of atom transfer radical polymerization(ATRP) and ckick chemistry.Firstly four-arm bromine-terminated polystyrene(PSt-Br)4 was obtained from ATRP of styrene using pentaerythritol tetra(2-bromoisobutyrate) as an initiator,and the(PSt-Br)4 was efficiently converted to the azido-terminated polymers[(PSt-N3)4] through the bromine substitution reaction with sodium azide.Furthermore,the(PSt-N3)4 reacted with propargyl 2,2-bis[2-(bromomethyl)propionato]propionyrate via a click reaction,1,3-dipolar cycloaddition reaction,and the polymer[(PSt-Br2)4] containing eight end-bromine was obtained.The(PSt-Br2)4 could further serve as a macroinitiator for the ATRP of methyl methacrylate(MMA).Accordingly,the dendrimer-like star polymer,[(PMMA)2PSt]4 was successfully prepared.The structure of [(PMMA)2PSt]4 was characterized via IR,1H NMR,GPC and DSC.展开更多
基金Project(21376271)supported by the National Natural Science Foundation of ChinaProject(2013)supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,China+2 种基金Projects(CL12129,201310533008)supported by the Undergraduates Innovative Training Foundation of Central South University,ChinaProject(Z12060)supported by the Undergraduate Free Exploration Innovation Foundation of Central South University,ChinaProject(CSUZC2013008)supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘Poly （methyl methacrylate） （PMMA） brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization （SI-ATRP）. Energy disperse spectroscopy （EDS） and atomic force microscopy （AFM） confirmed that PMMA brushes were successfully prepared on the silicon wafers, and the surface became more hydrophobic according to the contact angle of 69~. It is found that CuCI/1, 1, 4, 7, 10, 10-hexamethyl triethylenetetramine （HMTETA） system is more suitable than CuBr/N, N, N′, N″, N′″-pentamethyl diethylenetriamine （PMDETA） system to control the free radical polymerization of MMA in solution. Nevertheless, better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuC1/HMTETA due to higher activity and better reversibility of the former system.
文摘An efficient route to macrocyclic polymers via “click” cyclization was presented.The α-bromine and ω-alkyne PMMA were prepared using the standard ATRP technique,initiated with propargyl 2-bromoisobutyrate,Cu(Ⅰ)Br and N,N,N’,N″,N-pentamethyldiethylenetriamine(PMDETA).Azidation of the terminal bromine was followed in DMF with sodium azide,and α-azide,ω-alkyne PMMA precursor was obtained.Then the “click” cylcization of precursor between terminal azide and alkyne was carried out under the catalysis of CuBr/PMDETA,during the course of the reaction,a pseudo-high dilution technique was utilized to ensure the favored intramolecular cylcization.The nearly complete cylcization has been confirmed by a combination of IR,1H NMR and GPC analysis,and cyclo-PMMA with an Mn of 15000,PDI of 1.38 was obtained.
文摘A novel hydroxy-capped comb-like block polymer, poly[poly(ethylene glycol)](HCPEG), was prepared via atom transfer radical polymerization(ATRP) of α-methylacryloyl-ω-hydroxyl-poly(ethylene glycol). The polymerization kinetics of the PHPEGMA was studied by gel permeation chromatography and 1H NMR. The semilogarithmic plot of monomer conversion vs. reaction time increases linearly before the conversion is up to more than 70% and the number-average molecular weights(M_n) by GPC increased linearly with increase of the monomer conversion up to 100%, while the polydispersity index remained fairly narrow with M_w/M_n<1.2.
文摘A new approach to the synthesis of dendrimer-like star polymer,[(PMMA)2PSt]4,was presented via the combination of atom transfer radical polymerization(ATRP) and ckick chemistry.Firstly four-arm bromine-terminated polystyrene(PSt-Br)4 was obtained from ATRP of styrene using pentaerythritol tetra(2-bromoisobutyrate) as an initiator,and the(PSt-Br)4 was efficiently converted to the azido-terminated polymers[(PSt-N3)4] through the bromine substitution reaction with sodium azide.Furthermore,the(PSt-N3)4 reacted with propargyl 2,2-bis[2-(bromomethyl)propionato]propionyrate via a click reaction,1,3-dipolar cycloaddition reaction,and the polymer[(PSt-Br2)4] containing eight end-bromine was obtained.The(PSt-Br2)4 could further serve as a macroinitiator for the ATRP of methyl methacrylate(MMA).Accordingly,the dendrimer-like star polymer,[(PMMA)2PSt]4 was successfully prepared.The structure of [(PMMA)2PSt]4 was characterized via IR,1H NMR,GPC and DSC.
