The use of living, alkyllithium-initiated anionic polymerization to prepare chain-end functionalized polymers and heteroarm, star-branched polymers is discussed. The scope and limitations of specific termination react...The use of living, alkyllithium-initiated anionic polymerization to prepare chain-end functionalized polymers and heteroarm, star-branched polymers is discussed. The scope and limitations of specific termination reactions with a variety of electrophilic species are illustrated for carbonation, hydroxyethylation, amination, and sulfonation. The methodology of using substituted 1,1-diphenylethylenes to provide a general, quantitative functionalization procedure is outlined and illustrated with examples of amine and phenol end-functionalization. A methodology is described for the synthesis of functionalized, star-branched copolymers with compositionally heterogeneous arms of controlled molecular weight and narrow molecular weight distribution using 1, 3-bis(1-pbenylethenyl) benzene.展开更多
Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methac...Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methacrylate was carried out in the presence of a polyfunctional chain transfer agent,pentaerythritol tetrakis(3-mercaptopropinate).At appropriate monomer conversions,two-arm PMMA having two residual thiol groups at the chain center or three-arm PMMA having one residual thiol group at the core were o...展开更多
An amorphous,colorless,and highly transparent star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized from the poly(ethylene glycol)(PEG),pentaerythritol,and dichlorometh...An amorphous,colorless,and highly transparent star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized from the poly(ethylene glycol)(PEG),pentaerythritol,and dichloromethane by Williamson reaction.FTIR and ~1H-NMR measurement demonstrated that the polymer repeating units were C[CH_2-OCH_2O-(CH_2CH_2O)_m-CH_2O-(CH_2CH_2O)_n-CH_2O]_4.The polymer host held well mechanical properties for pentaerythritol cross-linking.The gel polymer electrolytes based on Lithium pe...展开更多
A star-shaped multifunctional styrene-isoprene copolymer was synthesized with n-BuLi as initiator, divinyl benzene as coupling agent, cyclobexane as solvent by living anionic polymerization. Using this polymer as graf...A star-shaped multifunctional styrene-isoprene copolymer was synthesized with n-BuLi as initiator, divinyl benzene as coupling agent, cyclobexane as solvent by living anionic polymerization. Using this polymer as grafting agent, a novel star-shaped branched polymer, containing several polyisobutylene, was prepared via cationic ~aolymerization. The star PS-b-PI and star-branched polyisobutylene were characterized by GPC, ＇HNMR and FT-IR, and the effects of different adding order and the amount of grafting agent were investigated.展开更多
The Rouse-Zimm model with slippage was improved and the basic parameters of modelwere modified to explain the rheological properties of star-type branched polymersolutions. The theoretical results show good agreement ...The Rouse-Zimm model with slippage was improved and the basic parameters of modelwere modified to explain the rheological properties of star-type branched polymersolutions. The theoretical results show good agreement with experimental data.展开更多
Newly designed miktoarm star-shaped copolymers made of poly[(benzyl methacrylate(BMA)-co-(ε-caprolacton)(CL)] and poly[(BMA-b-MMA-b-BMA)-co-ε-caprolacton)(CL)] were synthesized by combining ring-opening polymerizati...Newly designed miktoarm star-shaped copolymers made of poly[(benzyl methacrylate(BMA)-co-(ε-caprolacton)(CL)] and poly[(BMA-b-MMA-b-BMA)-co-ε-caprolacton)(CL)] were synthesized by combining ring-opening polymerization (ROP) of ε-caprolactone (CL) and poly(BMA) five membered lacton fuctionalized prepared via atom transfer radical polymerization (ATRP) of BMA, and ε-CL and P(BMA-b-MMA-b-BMA) dual functionalized diblock copolymer, in the presence of tin(II) bis(2-ethylhexanoate) (Sn(Oct)2). Although lactone ended poly(benzyl methacrylate) with ε-caprolactone monomer gave ring open polymerization by Sn(Oct)2, the macromonomer itself did not give any poly- merization The macromonomers, and the miktoarm star-shaped copolymers were analyzed by FT-IR and 1H-NMR spectroscopies and GPC (gel permeation chromatograph), Differential scanning calorimetry (DSC-50) and termo- gravimetric analysis (TGA-50). These copolymers exhibited the expected structure. The crystallization of star-shaped copolymers was studied by DSC. The results show that when the content of the BMA block increased, the Tm of the star-shaped block copolymer increased.展开更多
A series of high performance lubricants of water-soluble polymers with telechelic or star structures has been studied. Their average molecular weights (M) over bar are 1800-6000. The chemical structures of the lubrica...A series of high performance lubricants of water-soluble polymers with telechelic or star structures has been studied. Their average molecular weights (M) over bar are 1800-6000. The chemical structures of the lubricants are characterized by their hydrophilic groups (-CH2CH2O-), -COOH, -OH, -CONH2 and antiwear active elements (S,P,Zn and Mo). The results of assessing for the anti-wear property indicate that this kind of water-soluble polymeric lubricants possesses excellent watersolubility, lubricity and anti-wear property. A preliminary study on the anti-wear mechanism of the polymers is performed by means of electron probe and scanning electron microscopy (SEM).展开更多
A novel kind of hexa-armed fluorene-benzene copolymer based on a hexaazaisowurtzitane core was synthesized through Suzuki coupling polycondensation.The introduction of this bulky caged-core could not only enhance the ...A novel kind of hexa-armed fluorene-benzene copolymer based on a hexaazaisowurtzitane core was synthesized through Suzuki coupling polycondensation.The introduction of this bulky caged-core could not only enhance the photoluminescence quantum efficiency,but also improve the electroluminescence properties,especially suppress the common green-color emission of polyfluorenes(PFs) material during device operation.These features can be attributed to the successful suppression of PF's chain aggregation which prof...展开更多
Poly(vinyl alcohol)(PVA)has been widely used in industrial and consumer products.In this study,we aimed to address this challenge by synthesizing well-defined multiarm poly(vinyl acetate)(PVAc)through the use of nonhy...Poly(vinyl alcohol)(PVA)has been widely used in industrial and consumer products.In this study,we aimed to address this challenge by synthesizing well-defined multiarm poly(vinyl acetate)(PVAc)through the use of nonhydrolyzable vinyl ethertype multifunctional RAFT agents.The control over molecular weights was achieved by the RAFT process to afford polymers with dominant head-to-head linkages at the terminal.Especially,quantitative end-functionalization of the synthesized PVAc was performed using Michael thiol−ene or disulfide exchange reactions.Consequently,saponification of the PVAc enabled the synthesis of end-functionalized multiarm PVA in an efficient manner.This straightforward approach afforded well-defined functional PVAs,which enable further chemical modification,thus widening the utility of PVA in a range of applications,such as precisely controlled network synthesis and bioconjugation.展开更多
A novel star-comb polybutadiene(SC-PB) was synthesized with n-butyllithium(n-BuLi) as initiator,epoxidized star liquid polybutadiene(ESPB) as coupling agent,cyclohexane as solvent by living anionic polymerization and ...A novel star-comb polybutadiene(SC-PB) was synthesized with n-butyllithium(n-BuLi) as initiator,epoxidized star liquid polybutadiene(ESPB) as coupling agent,cyclohexane as solvent by living anionic polymerization and grafting-onto technology. The SC-PB was subsequently hydrogenated by homogeneous catalysis(catalytic hydrogenation using nickel naphthenate/ triisobutyl aluminum),to transform the SC-PB into the corresponding star-comb poly(ethylene-co-butene)(SC-PEB).The SC-PB was characterized by SEC-TALLS,~1...展开更多
We report here a method for the preparation of amphiphilic dendrimer-like copolymers with dendritic polystyrene (PS) core and protonated poly(2-vinyl pyridine)(P2VP) or poly(methacrylic acid)(PMAA) shell. The method e...We report here a method for the preparation of amphiphilic dendrimer-like copolymers with dendritic polystyrene (PS) core and protonated poly(2-vinyl pyridine)(P2VP) or poly(methacrylic acid)(PMAA) shell. The method employed the efficient coupling reaction of anionic living polymer chains and chlorosilane. The synthesis started from a functionalized 3rd generation dendritic polystyrene, G3PS-g-SiCl, used as the precursor. The dendrimer-like copolymer of styrene and 2-vinyl pyridine, G3PS-g-P2VP, was synthesized by direct coupling of living P2VPLi to the precursor. The dendrimer-like copolymer of styrene and Zer/-butyl methacrylate, G3PS-g-PtBMA, was synthesized by an indirect procedure in which a living polymer containing mainly PtBMA segment was attached to the precursor. Both methods resulted in the formation of dendrimer-like copolymers with the high molecular weights (up to 8.5 × 10^6 Da), large molecular sizes (diameter up to 73 nm), and dense shells (number of arms up to 1300). These products, G3PS-g-P2VP and G3PS-g- PtBMA, were protonated with trifluoroacetic acid and acidic hydrolyzed, respectively. After transformation, amphiphilic dendrimer-like copolymers, G3PS-g-P2VPH^+ and G3PS-g-PMAA, were obtained. Preliminary results on the solution properties of the amphiphilic products were presented.展开更多
HTEMPO-functionalized central cores were formed with divinylbenzene in ＇＇core first＇＇ method,and the four or five arms star polymers were built via controlled/living free radical photopolymerization.The four arms ...HTEMPO-functionalized central cores were formed with divinylbenzene in ＇＇core first＇＇ method,and the four or five arms star polymers were built via controlled/living free radical photopolymerization.The four arms star polymers were also prepared with controlled/living free radical photopolymerization in ＇＇arm first＇＇ method.The resulting polymers had been confirmed by GPC and 1 H NMR.It showed that the star polymers had low polydispersities and molecular weight（M n） with the 85,000-560,000 g/mol range.展开更多
A series of 3-arm ABC and AA＇B and 4-arm ABCD, AA＇BC and AA＇A＂B heteroarm star polymers comprising one poly（4-methylphenyl vinyl sulfoxide） segment and other segments such as polystyrene, poly（a-methylstyrene）...A series of 3-arm ABC and AA＇B and 4-arm ABCD, AA＇BC and AA＇A＂B heteroarm star polymers comprising one poly（4-methylphenyl vinyl sulfoxide） segment and other segments such as polystyrene, poly（a-methylstyrene）, poly（4-methoxystyrene） and poly（4-trimethylsilylstyrene） were synthesized by living anionic polymerization based on diphenylethylene （DPE） chemistry. The DPE-functionalized polymers were synthesized by iterative methodology, and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers. The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide （MePVSO） initiated from the in situ formed polymer anion with two or three polymer segments. The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well. Both approaches could afford the target heteroarm star polymers with predetermined molecular weight, narrow molecular weight distribution （Mw/Mn 〈 1.03） and desired composition, evidenced by SEC, 1H-NMR and SLS analyses. These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.展开更多
We report a newly synthesized polymer of a star-shaped porphyrin compound(TPA-FxP) with four oligofluorene arms at its meso positions with the pronounced enhancement of the two-photon properties and the generation of ...We report a newly synthesized polymer of a star-shaped porphyrin compound(TPA-FxP) with four oligofluorene arms at its meso positions with the pronounced enhancement of the two-photon properties and the generation of singlet oxygen by utilizing the two-photon excited fluorescence resonance energy transfer.The steady-state spectra and transient triplet-triplet absorption spectra give evidence that the enhanced two-photon absorption cross section results from not only the through-space energy transfer(Frster) but also the through-bond energy transfer between conjugated peripheral oligofluorene arms and the porphyrin core.The two-photon absorption cross section at 780 nm up to 3360 GM(1 GM = 10-50 cm4·s/photon) of TPA-FxP was obtained,which is comparable to the highest values reported from other similar chemically modified porphyrin core compounds.Furthermore,the enhanced production of singlet oxygen under two-photon absorption conditions is also reported.展开更多
文摘The use of living, alkyllithium-initiated anionic polymerization to prepare chain-end functionalized polymers and heteroarm, star-branched polymers is discussed. The scope and limitations of specific termination reactions with a variety of electrophilic species are illustrated for carbonation, hydroxyethylation, amination, and sulfonation. The methodology of using substituted 1,1-diphenylethylenes to provide a general, quantitative functionalization procedure is outlined and illustrated with examples of amine and phenol end-functionalization. A methodology is described for the synthesis of functionalized, star-branched copolymers with compositionally heterogeneous arms of controlled molecular weight and narrow molecular weight distribution using 1, 3-bis(1-pbenylethenyl) benzene.
文摘Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methacrylate was carried out in the presence of a polyfunctional chain transfer agent,pentaerythritol tetrakis(3-mercaptopropinate).At appropriate monomer conversions,two-arm PMMA having two residual thiol groups at the chain center or three-arm PMMA having one residual thiol group at the core were o...
文摘An amorphous,colorless,and highly transparent star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized from the poly(ethylene glycol)(PEG),pentaerythritol,and dichloromethane by Williamson reaction.FTIR and ~1H-NMR measurement demonstrated that the polymer repeating units were C[CH_2-OCH_2O-(CH_2CH_2O)_m-CH_2O-(CH_2CH_2O)_n-CH_2O]_4.The polymer host held well mechanical properties for pentaerythritol cross-linking.The gel polymer electrolytes based on Lithium pe...
文摘A star-shaped multifunctional styrene-isoprene copolymer was synthesized with n-BuLi as initiator, divinyl benzene as coupling agent, cyclobexane as solvent by living anionic polymerization. Using this polymer as grafting agent, a novel star-shaped branched polymer, containing several polyisobutylene, was prepared via cationic ~aolymerization. The star PS-b-PI and star-branched polyisobutylene were characterized by GPC, ＇HNMR and FT-IR, and the effects of different adding order and the amount of grafting agent were investigated.
文摘The Rouse-Zimm model with slippage was improved and the basic parameters of modelwere modified to explain the rheological properties of star-type branched polymersolutions. The theoretical results show good agreement with experimental data.
基金The authors wish to thank the Firat University Research Fund for financial support of this Project(FUBAP-1650)M.Fatih Coskun,who provided chromatograms(GPC)at our university.
文摘Newly designed miktoarm star-shaped copolymers made of poly[(benzyl methacrylate(BMA)-co-(ε-caprolacton)(CL)] and poly[(BMA-b-MMA-b-BMA)-co-ε-caprolacton)(CL)] were synthesized by combining ring-opening polymerization (ROP) of ε-caprolactone (CL) and poly(BMA) five membered lacton fuctionalized prepared via atom transfer radical polymerization (ATRP) of BMA, and ε-CL and P(BMA-b-MMA-b-BMA) dual functionalized diblock copolymer, in the presence of tin(II) bis(2-ethylhexanoate) (Sn(Oct)2). Although lactone ended poly(benzyl methacrylate) with ε-caprolactone monomer gave ring open polymerization by Sn(Oct)2, the macromonomer itself did not give any poly- merization The macromonomers, and the miktoarm star-shaped copolymers were analyzed by FT-IR and 1H-NMR spectroscopies and GPC (gel permeation chromatograph), Differential scanning calorimetry (DSC-50) and termo- gravimetric analysis (TGA-50). These copolymers exhibited the expected structure. The crystallization of star-shaped copolymers was studied by DSC. The results show that when the content of the BMA block increased, the Tm of the star-shaped block copolymer increased.
基金This study is supported by the National Natural Science Foundation of China
文摘A series of high performance lubricants of water-soluble polymers with telechelic or star structures has been studied. Their average molecular weights (M) over bar are 1800-6000. The chemical structures of the lubricants are characterized by their hydrophilic groups (-CH2CH2O-), -COOH, -OH, -CONH2 and antiwear active elements (S,P,Zn and Mo). The results of assessing for the anti-wear property indicate that this kind of water-soluble polymeric lubricants possesses excellent watersolubility, lubricity and anti-wear property. A preliminary study on the anti-wear mechanism of the polymers is performed by means of electron probe and scanning electron microscopy (SEM).
文摘A novel kind of hexa-armed fluorene-benzene copolymer based on a hexaazaisowurtzitane core was synthesized through Suzuki coupling polycondensation.The introduction of this bulky caged-core could not only enhance the photoluminescence quantum efficiency,but also improve the electroluminescence properties,especially suppress the common green-color emission of polyfluorenes(PFs) material during device operation.These features can be attributed to the successful suppression of PF's chain aggregation which prof...
文摘Poly(vinyl alcohol)(PVA)has been widely used in industrial and consumer products.In this study,we aimed to address this challenge by synthesizing well-defined multiarm poly(vinyl acetate)(PVAc)through the use of nonhydrolyzable vinyl ethertype multifunctional RAFT agents.The control over molecular weights was achieved by the RAFT process to afford polymers with dominant head-to-head linkages at the terminal.Especially,quantitative end-functionalization of the synthesized PVAc was performed using Michael thiol−ene or disulfide exchange reactions.Consequently,saponification of the PVAc enabled the synthesis of end-functionalized multiarm PVA in an efficient manner.This straightforward approach afforded well-defined functional PVAs,which enable further chemical modification,thus widening the utility of PVA in a range of applications,such as precisely controlled network synthesis and bioconjugation.
基金sponsored by the National High Technology Research and Development Program of China(No. 2007AA03Z532)the National Natural Science Foundation of China(Nos.20674007 & 20774015)
文摘A novel star-comb polybutadiene(SC-PB) was synthesized with n-butyllithium(n-BuLi) as initiator,epoxidized star liquid polybutadiene(ESPB) as coupling agent,cyclohexane as solvent by living anionic polymerization and grafting-onto technology. The SC-PB was subsequently hydrogenated by homogeneous catalysis(catalytic hydrogenation using nickel naphthenate/ triisobutyl aluminum),to transform the SC-PB into the corresponding star-comb poly(ethylene-co-butene)(SC-PEB).The SC-PB was characterized by SEC-TALLS,~1...
基金financially supported by the National Natural Science Foundation of China (No. 21474016)Senior Visiting Scholar Foundation of Key Laboratory in Fudan University (Nos. 16FHJ08 & 18FGJ01)
文摘We report here a method for the preparation of amphiphilic dendrimer-like copolymers with dendritic polystyrene (PS) core and protonated poly(2-vinyl pyridine)(P2VP) or poly(methacrylic acid)(PMAA) shell. The method employed the efficient coupling reaction of anionic living polymer chains and chlorosilane. The synthesis started from a functionalized 3rd generation dendritic polystyrene, G3PS-g-SiCl, used as the precursor. The dendrimer-like copolymer of styrene and 2-vinyl pyridine, G3PS-g-P2VP, was synthesized by direct coupling of living P2VPLi to the precursor. The dendrimer-like copolymer of styrene and Zer/-butyl methacrylate, G3PS-g-PtBMA, was synthesized by an indirect procedure in which a living polymer containing mainly PtBMA segment was attached to the precursor. Both methods resulted in the formation of dendrimer-like copolymers with the high molecular weights (up to 8.5 × 10^6 Da), large molecular sizes (diameter up to 73 nm), and dense shells (number of arms up to 1300). These products, G3PS-g-P2VP and G3PS-g- PtBMA, were protonated with trifluoroacetic acid and acidic hydrolyzed, respectively. After transformation, amphiphilic dendrimer-like copolymers, G3PS-g-P2VPH^+ and G3PS-g-PMAA, were obtained. Preliminary results on the solution properties of the amphiphilic products were presented.
文摘HTEMPO-functionalized central cores were formed with divinylbenzene in ＇＇core first＇＇ method,and the four or five arms star polymers were built via controlled/living free radical photopolymerization.The four arms star polymers were also prepared with controlled/living free radical photopolymerization in ＇＇arm first＇＇ method.The resulting polymers had been confirmed by GPC and 1 H NMR.It showed that the star polymers had low polydispersities and molecular weight（M n） with the 85,000-560,000 g/mol range.
基金supported by the National Natural Science Foundation of China(Nos.20844001 and 20874067)the Key Project of Chinese Ministry of Education(No.209049)Natural Science Fund for Colleges and Universities of Jiangsu Province(No.08KJB150015).
文摘A series of 3-arm ABC and AA＇B and 4-arm ABCD, AA＇BC and AA＇A＂B heteroarm star polymers comprising one poly（4-methylphenyl vinyl sulfoxide） segment and other segments such as polystyrene, poly（a-methylstyrene）, poly（4-methoxystyrene） and poly（4-trimethylsilylstyrene） were synthesized by living anionic polymerization based on diphenylethylene （DPE） chemistry. The DPE-functionalized polymers were synthesized by iterative methodology, and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers. The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide （MePVSO） initiated from the in situ formed polymer anion with two or three polymer segments. The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well. Both approaches could afford the target heteroarm star polymers with predetermined molecular weight, narrow molecular weight distribution （Mw/Mn 〈 1.03） and desired composition, evidenced by SEC, 1H-NMR and SLS analyses. These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20773139, 20825314, and 20833008)State Key Project for Fundamental Research (Grant Nos. 2006CB806000 and 2007CB815200)the Chinese Academy of Sciences (Grant No. KJCX2.Y.W.H06)
文摘We report a newly synthesized polymer of a star-shaped porphyrin compound(TPA-FxP) with four oligofluorene arms at its meso positions with the pronounced enhancement of the two-photon properties and the generation of singlet oxygen by utilizing the two-photon excited fluorescence resonance energy transfer.The steady-state spectra and transient triplet-triplet absorption spectra give evidence that the enhanced two-photon absorption cross section results from not only the through-space energy transfer(Frster) but also the through-bond energy transfer between conjugated peripheral oligofluorene arms and the porphyrin core.The two-photon absorption cross section at 780 nm up to 3360 GM(1 GM = 10-50 cm4·s/photon) of TPA-FxP was obtained,which is comparable to the highest values reported from other similar chemically modified porphyrin core compounds.Furthermore,the enhanced production of singlet oxygen under two-photon absorption conditions is also reported.
