A new kind of multifunctional macromolecular initiator with Sn-C bonds and polydiene arms was synthesized by living anionic polymerization. At first, polydiene-stannum chloride （PD-SnCl3） was prepared by the reactio...A new kind of multifunctional macromolecular initiator with Sn-C bonds and polydiene arms was synthesized by living anionic polymerization. At first, polydiene-stannum chloride （PD-SnCl3） was prepared by the reaction of n-butyl-Li （n-BuLi）, stannic chloride （SnCl4） and diene. Then PD-SnCl3 was used to react with the dilithium initiator to prepare the multifunctional organic macromolecular initiators. The result suggested that the initiators had a remarkable yield by GPC, nearly 90%. By using these multifunctional macromolecular initiators, styrene and butadiene were effectively polymefized via anionic polymerization, which gave birth to novel miktoarm star copolymers. The relative molecular weight and polydispersity index, microstructure contents, copolymerization components, glass transition temperature （Tg） and morphology of the miktoarm star copolymers were investigated by GPC-UV, ~H NMR, DSC and TEM, respectively. 2009 Xing Ying Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
A novel multifunctional macromolecular organolithium initiator （PD-Sn-（RLi）3） was prepared via living anionic polymerization and used for the synthesis of miktoarm star copolymers in cyclohexane. The average molec...A novel multifunctional macromolecular organolithium initiator （PD-Sn-（RLi）3） was prepared via living anionic polymerization and used for the synthesis of miktoarm star copolymers in cyclohexane. The average molecular weight, polydispersity index, microstructure and unit composition of the miktoarm star copolymers were characterized with GPC and 1H-NMR. Performances of the miktoarm star styrene-butadiene rubbers were investigated in comparison with those of the blend rubbers such as the tin-coupled star-shaped random copolymers of styrene-butadiene rubber（S-SBR）/natural rubber （NR） blend rubber and S-SBR/Cis-1, 4-polybutadiene rubber （Cis-BR） blend rubber.展开更多
In order to obtain the optimized structure rubber, a novel miktoarm star styrene-butadiene rubber （MS- SBR） was initiated by a multifunctional macromolecular initiator with polydiene arm and Sn-C bond. The propertie...In order to obtain the optimized structure rubber, a novel miktoarm star styrene-butadiene rubber （MS- SBR） was initiated by a multifunctional macromolecular initiator with polydiene arm and Sn-C bond. The properties of MS-SBR were investigated with respect to the morphology, mechanical properties, and dynamic viscoelasticity in comparison with those of the blends, natural rubber （NR）/star styrene-butadiene random rubber （S-SBR） blend rubber and cis-l,4-polybutadiene rubber （cis-BR）/S-SBR blend rubber. The samples were analyzed using transmission elec- tron microscopy （TEM）, dynamic mechanical thermal analyzer （DMTA）, and mechanical properties test. The analy- sis results show that MS-SBR possesses the desired combination of low rolling resistance and high antiskid resistance, and is promising for application in high performance tire tread.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
We report on the fabrication of self-assembled micelles from ABC-type miktoarm star polypeptide hybrid copolymers consisting of poly（ethylene oxide）, poly（L-lysine）, and poly（e-caprolactone） arms, PEO（-b-PLL）-...We report on the fabrication of self-assembled micelles from ABC-type miktoarm star polypeptide hybrid copolymers consisting of poly（ethylene oxide）, poly（L-lysine）, and poly（e-caprolactone） arms, PEO（-b-PLL）-b-PCL, and their functional applications as co-delivery nanocarriers of chemotherapeutic drugs and plasmid DNA. Miktoarm star copolymer precursors, PEO（-b-PZLL）-b-PCL, were synthesized at first via the combination of consecutive ＂click＂ reactions and ring-opening polymerizations （ROP）, where PZLL is poly（e-benzyloxycarbonyl-L-lysine）. Subsequently, the deprotection of PZLL arm afforded amphiphilic miktoarm star copolymers, PEO（-b-PLL）-b-PCL. In aqueous media at pH 7.4, PEO（-b-PLL）-b-PCL self-assembles into micelles consisting of PCL cores and hydrophilic PEO/PLL hybrid coronas. The hydrophobic micellar cores can effectively encapsulate model hydrophobic anticancer drug, paclitaxel; whereas positively charged PLL arms within mixed micellar corona are capable of forming electrostatic polyplexes with negatively charged plasmid DNA （pDNA） at N/P ratios higher than ca. 2. Thus, PEO（-b-PLL）-b-PCL micelles can act as co-delivery nanovehicles for both chemotherapeutic drugs and genes. Furthermore, polyplexes of pDNA with paclitaxel-loaded PEO（-b- PLL）-b-PCL micelles exhibited improved transfection efficiency compared to that of pDNA/blank micelles. We expect that the reported strategy of varying chain topologies for the fabrication of co-delivery polymeric nanocarriers can be further applied to integrate with other advantageous functions such as targeting, imaging, and diagnostics.展开更多
Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of...Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (Mn=122 kDa) via one-pot parallel click chemistry.The parallel click grafting strategy was demonstrated to be highly efficient (～100%),very fast (～ 2 h) and well controllable to the amphilicity of molecular brushes.Through adjusting the feeding ratio of hydrophobic and hydrophilic arms,a series of brushes with different arm ratios were readily obtained.The resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR),Fourier transform infrared (FT-IR) spectroscopy,gel permeation chromatography (GPC),and differential scanning calorimetry (DSC) measurements.The spherical molecular brushes showed high molecular weights up to 230 kDa,and thus could be visualized by atomic force microscopy (AFM).AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic arms.The brushes could self-assemble hierarchically into spherical micelles,and network-like fibre structures,and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of brushes.In addition,this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation,which promises the potential application of spherical molecular brushes in supramolecular chemistry.展开更多
It is well-known that amphiphilic star-shaped copolymers can self-assemble in selective solvents to form complicated micellar constructs as a synergistic result of both the topological constraints and relative volume ...It is well-known that amphiphilic star-shaped copolymers can self-assemble in selective solvents to form complicated micellar constructs as a synergistic result of both the topological constraints and relative volume fractions of the arms.Although the association phenomena of amphiphilic stars have been observed in nonselective solvents,both the structural detail and formation mechanism of these associates are not clear yet.Moreover,these experimental observations are controversial with respect to molecularly dispersed starlike copolymers in nonselective solvents as is popularly believed.To clarify these issues,we have synthesized a series of polyoxometalate-based polystyrene-poly(ethylene glycol)(PS-PEG)miktoarm star supramolecular copolymers(SEW-1–5)by coupling a Keggin-type polyoxometalate of K4[α-SiW12O40]with 1,2,3-triazolium bridged block copolymers of-PSn-b+-PEGmI-(n=17,26,39,57,81;m=45)through ionic exchange reactions,respectively.TEM imaging,contact angle and 1H NMR studies reveal that SEW-2–5 self-assemble in chloroform,THF,and toluene to create micellelike aggregates ranging from cylinder to sphere with a PS corona and a PEG core,while for SEW-1,reverse bilayers are captured with a PEG corona and a PS core.Among these aggregates,the Keggin clusters of[α-SiW12O40]4-localize at the core-corona interfaces between PS and PEG.In terms of solvent quality,chloroform,THF,and toluene are only slightly poorer for PEG than that for PS with a relative order of chloroform<THF<toluene.These unexpected aggregates originate from the topological constraints of the chemically different arms of PS and PEG in the miktoarm stars,where the weak incompatibility between the PS and PEG arms is intensified appropriately.The presence of the reverse bilayered structures of SEW-1 is due to the magnified steric hindrance of the PEG45 arm with decreasing the molecular weight of the PS17 arm.However,to the best of our knowledge,these are the first examples clearly indicating that miktoarm star copolymers can self-assemble in common good solvents or slightly selective solvents to generate micellelike aggregates.This scenario is not only in sharp contrast to the intuitively considered behavior of unimolecular miktoarm stars in nonselective solvents,but also rather different from the conventional selfassembly behavior of amphiphilic star copolymers in selective solvents.展开更多
通过胺化反应和原子转移自由基聚合(ATRP),合成了以β-环糊精(CD)为"核",以1条聚乙二醇(MPEG)和2～4条聚N-异丙基丙烯酰胺为"臂"的双亲水性星型杂臂聚合物(MPEG-CD-PNIPAMx).通过1 H NMR、13 C NMR和凝胶渗透色谱/...通过胺化反应和原子转移自由基聚合(ATRP),合成了以β-环糊精(CD)为"核",以1条聚乙二醇(MPEG)和2～4条聚N-异丙基丙烯酰胺为"臂"的双亲水性星型杂臂聚合物(MPEG-CD-PNIPAMx).通过1 H NMR、13 C NMR和凝胶渗透色谱/多角度激光光散射联用(SEC/MALLS)对其结构进行了表征.对1 H NMR峰面积积分计算得到聚N-异丙基丙烯酰胺"臂"数为2～4个.通过紫外-可见分光光度计测得该星型大分子的低溶液临界温度(LCST)为37℃.MPEG-CD-PNIPAMx在其水溶液温度达到LCST以上时呈现两亲性,并通过疏水相互作用自组装成以聚N-异丙基丙烯酰胺为"核",以β-环糊精及聚乙二醇为"壳"的纳米级胶束粒子.通过测定MPEG-CD-PNIPAMx及其胶束粒子在芘溶液中的荧光光谱,发现胶束粒子对疏水性客体小分子的包合可发生在壳层的β-环糊精疏水性空腔和胶束粒子的疏水性内核中.展开更多
基金supported by National Natural Science Foundation of China(No.50573005)
文摘A new kind of multifunctional macromolecular initiator with Sn-C bonds and polydiene arms was synthesized by living anionic polymerization. At first, polydiene-stannum chloride （PD-SnCl3） was prepared by the reaction of n-butyl-Li （n-BuLi）, stannic chloride （SnCl4） and diene. Then PD-SnCl3 was used to react with the dilithium initiator to prepare the multifunctional organic macromolecular initiators. The result suggested that the initiators had a remarkable yield by GPC, nearly 90%. By using these multifunctional macromolecular initiators, styrene and butadiene were effectively polymefized via anionic polymerization, which gave birth to novel miktoarm star copolymers. The relative molecular weight and polydispersity index, microstructure contents, copolymerization components, glass transition temperature （Tg） and morphology of the miktoarm star copolymers were investigated by GPC-UV, ~H NMR, DSC and TEM, respectively. 2009 Xing Ying Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金Supported by the National Natural Science Foundation of China(50573005)
文摘A novel multifunctional macromolecular organolithium initiator （PD-Sn-（RLi）3） was prepared via living anionic polymerization and used for the synthesis of miktoarm star copolymers in cyclohexane. The average molecular weight, polydispersity index, microstructure and unit composition of the miktoarm star copolymers were characterized with GPC and 1H-NMR. Performances of the miktoarm star styrene-butadiene rubbers were investigated in comparison with those of the blend rubbers such as the tin-coupled star-shaped random copolymers of styrene-butadiene rubber（S-SBR）/natural rubber （NR） blend rubber and S-SBR/Cis-1, 4-polybutadiene rubber （Cis-BR） blend rubber.
基金Supported by National Natural Science Foundation of China (No.50573005)
文摘In order to obtain the optimized structure rubber, a novel miktoarm star styrene-butadiene rubber （MS- SBR） was initiated by a multifunctional macromolecular initiator with polydiene arm and Sn-C bond. The properties of MS-SBR were investigated with respect to the morphology, mechanical properties, and dynamic viscoelasticity in comparison with those of the blends, natural rubber （NR）/star styrene-butadiene random rubber （S-SBR） blend rubber and cis-l,4-polybutadiene rubber （cis-BR）/S-SBR blend rubber. The samples were analyzed using transmission elec- tron microscopy （TEM）, dynamic mechanical thermal analyzer （DMTA）, and mechanical properties test. The analy- sis results show that MS-SBR possesses the desired combination of low rolling resistance and high antiskid resistance, and is promising for application in high performance tire tread.
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supported by the National Natural Science Foundation of China (Nos. 21274137, 91027026 and 51033005)Fundamental Research Funds for the Central UniversitiesSpecialized Research Fund for the Doctoral Program of Higher Education (SRFDP, 20123402130010)
文摘We report on the fabrication of self-assembled micelles from ABC-type miktoarm star polypeptide hybrid copolymers consisting of poly（ethylene oxide）, poly（L-lysine）, and poly（e-caprolactone） arms, PEO（-b-PLL）-b-PCL, and their functional applications as co-delivery nanocarriers of chemotherapeutic drugs and plasmid DNA. Miktoarm star copolymer precursors, PEO（-b-PZLL）-b-PCL, were synthesized at first via the combination of consecutive ＂click＂ reactions and ring-opening polymerizations （ROP）, where PZLL is poly（e-benzyloxycarbonyl-L-lysine）. Subsequently, the deprotection of PZLL arm afforded amphiphilic miktoarm star copolymers, PEO（-b-PLL）-b-PCL. In aqueous media at pH 7.4, PEO（-b-PLL）-b-PCL self-assembles into micelles consisting of PCL cores and hydrophilic PEO/PLL hybrid coronas. The hydrophobic micellar cores can effectively encapsulate model hydrophobic anticancer drug, paclitaxel; whereas positively charged PLL arms within mixed micellar corona are capable of forming electrostatic polyplexes with negatively charged plasmid DNA （pDNA） at N/P ratios higher than ca. 2. Thus, PEO（-b-PLL）-b-PCL micelles can act as co-delivery nanovehicles for both chemotherapeutic drugs and genes. Furthermore, polyplexes of pDNA with paclitaxel-loaded PEO（-b- PLL）-b-PCL micelles exhibited improved transfection efficiency compared to that of pDNA/blank micelles. We expect that the reported strategy of varying chain topologies for the fabrication of co-delivery polymeric nanocarriers can be further applied to integrate with other advantageous functions such as targeting, imaging, and diagnostics.
基金supported by the National Natural Science Foundation of China(50773038 & 20974093)National Basic Research Program of China(973 Program)(2007CB936000)+2 种基金the Fundamental Research Funds for the Central Universities(2009QNA4040)Qianjiang Talent Foundation of Zhejiang Province(2010R10021)the Foundation for the Author of National Excellent Doctoral Dissertation of China(200527)
文摘Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (Mn=122 kDa) via one-pot parallel click chemistry.The parallel click grafting strategy was demonstrated to be highly efficient (～100%),very fast (～ 2 h) and well controllable to the amphilicity of molecular brushes.Through adjusting the feeding ratio of hydrophobic and hydrophilic arms,a series of brushes with different arm ratios were readily obtained.The resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR),Fourier transform infrared (FT-IR) spectroscopy,gel permeation chromatography (GPC),and differential scanning calorimetry (DSC) measurements.The spherical molecular brushes showed high molecular weights up to 230 kDa,and thus could be visualized by atomic force microscopy (AFM).AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic arms.The brushes could self-assemble hierarchically into spherical micelles,and network-like fibre structures,and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of brushes.In addition,this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation,which promises the potential application of spherical molecular brushes in supramolecular chemistry.
基金supported by the National Natural Science Foundation of China(21674044,21504036,21474044)the Open Project of State Key Laboratory of Supramolecular Structure and Materials of Jilin University(sklssm201903)the Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences(2018-25)。
文摘It is well-known that amphiphilic star-shaped copolymers can self-assemble in selective solvents to form complicated micellar constructs as a synergistic result of both the topological constraints and relative volume fractions of the arms.Although the association phenomena of amphiphilic stars have been observed in nonselective solvents,both the structural detail and formation mechanism of these associates are not clear yet.Moreover,these experimental observations are controversial with respect to molecularly dispersed starlike copolymers in nonselective solvents as is popularly believed.To clarify these issues,we have synthesized a series of polyoxometalate-based polystyrene-poly(ethylene glycol)(PS-PEG)miktoarm star supramolecular copolymers(SEW-1–5)by coupling a Keggin-type polyoxometalate of K4[α-SiW12O40]with 1,2,3-triazolium bridged block copolymers of-PSn-b+-PEGmI-(n=17,26,39,57,81;m=45)through ionic exchange reactions,respectively.TEM imaging,contact angle and 1H NMR studies reveal that SEW-2–5 self-assemble in chloroform,THF,and toluene to create micellelike aggregates ranging from cylinder to sphere with a PS corona and a PEG core,while for SEW-1,reverse bilayers are captured with a PEG corona and a PS core.Among these aggregates,the Keggin clusters of[α-SiW12O40]4-localize at the core-corona interfaces between PS and PEG.In terms of solvent quality,chloroform,THF,and toluene are only slightly poorer for PEG than that for PS with a relative order of chloroform<THF<toluene.These unexpected aggregates originate from the topological constraints of the chemically different arms of PS and PEG in the miktoarm stars,where the weak incompatibility between the PS and PEG arms is intensified appropriately.The presence of the reverse bilayered structures of SEW-1 is due to the magnified steric hindrance of the PEG45 arm with decreasing the molecular weight of the PS17 arm.However,to the best of our knowledge,these are the first examples clearly indicating that miktoarm star copolymers can self-assemble in common good solvents or slightly selective solvents to generate micellelike aggregates.This scenario is not only in sharp contrast to the intuitively considered behavior of unimolecular miktoarm stars in nonselective solvents,but also rather different from the conventional selfassembly behavior of amphiphilic star copolymers in selective solvents.
文摘通过胺化反应和原子转移自由基聚合(ATRP),合成了以β-环糊精(CD)为"核",以1条聚乙二醇(MPEG)和2～4条聚N-异丙基丙烯酰胺为"臂"的双亲水性星型杂臂聚合物(MPEG-CD-PNIPAMx).通过1 H NMR、13 C NMR和凝胶渗透色谱/多角度激光光散射联用(SEC/MALLS)对其结构进行了表征.对1 H NMR峰面积积分计算得到聚N-异丙基丙烯酰胺"臂"数为2～4个.通过紫外-可见分光光度计测得该星型大分子的低溶液临界温度(LCST)为37℃.MPEG-CD-PNIPAMx在其水溶液温度达到LCST以上时呈现两亲性,并通过疏水相互作用自组装成以聚N-异丙基丙烯酰胺为"核",以β-环糊精及聚乙二醇为"壳"的纳米级胶束粒子.通过测定MPEG-CD-PNIPAMx及其胶束粒子在芘溶液中的荧光光谱,发现胶束粒子对疏水性客体小分子的包合可发生在壳层的β-环糊精疏水性空腔和胶束粒子的疏水性内核中.
