Anionic Polymerization (anionic + polymerization)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Anionic Polymerization

  • sequential anionic polymerization


  • Selected Abstracts


    Synthesis of Half-Channels by the Anionic Polymerization of Ethylene Oxide Initiated by Modified Cyclodextrin

    ADVANCED MATERIALS, Issue 40 2009
    Nezha Badi
    Amphiphilic star-shaped oligomers are produced by anionic polymerization of ethylene oxide (EO) using per-2,3-di- O -heptyl- , -(or ,)cyclodextrins as initiators , a versatile way of synthesizing artificial channels bearing one polyEO branch per glucose unit. The behavior of the amphiphilic molecules in lipid membranes is studied by electrical measurements, which confirms the formation of transient, well-defined dimeric ionic channels (see figure). [source]


    Two-Dimensional Chromatography of Complex Polymers, 7 , Detailed Study of Polystyrene- block -Polyisoprene Diblock Copolymers Prepared by Sequential Anionic Polymerization and Coupling Chemistry

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19 2008
    Valentina Mass
    Abstract Two-dimensional chromatographic methods were developed using LC-CC in the first and SEC in the second dimension. These methods were applied for the investigation of PS- b -PI diblock copolymers synthesized by different approaches: sequential living anionic polymerization and coupling of living precursor blocks. The first dimension separates according to the individual block length of PS or PI blocks, whereas the second dimension separates with respect to the total molar masses of components. 2D-LC analysis provides information on the purity of the reaction products, the presence of by-products, the chemical compositions and the molar masses of all product components. The accuracy and selectivity of 2D-LC is discussed. [source]


    Anionic Polymerization of 1,3-Cyclohexadiene: Reactivity of Poly(1,3-cyclohexadienyl)lithium

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 23 2006
    Itaru Natori
    Abstract Summary: The reactivity of poly(1,3-cyclohexadienyl)lithium (PCHDLi), as a species for the propagation of the anionic polymerization of 1,3-cyclohexadiene (1,3-CHD), was examined using a post-polymerization reaction of PCHDLi and 9-bromofluorene (9-BFL). The degree of nucleophilicity of the PCHDLi systems was determined as PCHDLi/1,4-diazabicyclo[2,2,2]octane (DABCO),>,PCHDLi/N,N,N,,N, -tetramethylethylenediamine (TMEDA),>,PCHDLi. The nucleophilicity of PCHDLi was strengthened by the complexation of TMEDA to Li, and was saturated when the TMEDA/Li molar ratio was over 1.0. The rate of polymerization increased with increasing nucleophilicity of PCHDLi. In addition, the molar ratio of the 1,2-addition (1,2-CHD unit)/1,4-addition (1,4-CHD unit) seemed to be strongly affected by both the nucleophilicity of PCHDLi and the steric hindrance of CLi bonds in PCHDLi. Post-polymerization reaction of poly(1,3-cyclohexadienyl)lithium (PCHDLi) and 9-bromofluorene (9-BFL). [source]


    Effect of LiClO4 and LiCl Additives on the Kinetics of Anionic Polymerization of Methyl Methacrylate in Toluene-Tetrahydrofuran Mixed Solvent

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2003
    Mahua G. Dhara
    Abstract The kinetics of anionic polymerization of MMA has been studied at ,78,C in toluene-THF (9:1 v/v) using 1,1,-diphenylhexyl lithium as initiator in the presence of lithium perchlorate and lithium chloride as Lewis acid additives. The control of the polymerization is lost in the absence of additives as evident from the non-linear first-order time-conversion plot and polymers with broad multimodal molecular weight distribution. The presence of LiClO4 and LiCl in 10:1 and 5:1 ratio, respectively, over the initiator brings about sufficient control, yielding polymers of narrow unimodal distribution throughout the polymerization. The reaction in the presence of the additives follows first-order kinetics free of termination and transfer. Moreover, the order with respect to the active centers is found to be almost unity, which signifies a probable disaggregation of ion-pairs to a single complexed propagating species. GPC elugrams at different conversions for MMA polymerization in the presence of LiClO4. [source]


    Defined Poly[styrene- block -(ferrocenylmethyl methacrylate)] Diblock Copolymers via Living Anionic Polymerization

    MACROMOLECULAR RAPID COMMUNICATIONS, Issue 17 2009
    Markus Gallei
    Abstract Ferrocenylmethyl methacrylate (FMMA) is one of the very few metallocene-based monomers that are promising candidates for truly living anionic polymerization. Nevertheless, FMMA homopolymers with a narrow polydispersity, or block copolymerization studies that result in satisfying blocking efficiencies, are unknown so far. Here we describe a procedure that leads to highly regular FMMA-based polymers for the first time, characterized by polydispersity indices (PDI) of less that 1.05 and very high blocking efficiencies (>95%) in sequential copolymerization with styrene. Some of the obtained poly[styrene- block -(ferrocenylmethyl methacrylate)]s show unusual microphase morphologies, presumably the consequence of high Tgs causing ,frustrated' non-equilibrium states. [source]


    Kinetics of the Anionic Polymerization of Buta-1,3-diene Considering Different Reactivities of the cis, trans and vinyl Structural Units

    MACROMOLECULAR REACTION ENGINEERING, Issue 5 2008
    Jos A. Tenorio Lpez
    Abstract The anionic solution polymerization of buta-1,3-diene was modeled, considering the reactivity of the active sites to be different due to varying geometric configurations. With the first-order Markov model, expressions for the fraction of active sites and dyad distribution were obtained. The rate constants were determined by fitting to the conversion and dyad experimental data using the nonlinear least squares method. The kinetic model shows that the microstructure and the dyads do not depend on initiator and butadiene concentration but only on rate constants. Without a modifier, the butadiene addition mechanism is entropic; with a modifier, the mechanism changes to entropic-enthalpic. [source]


    Aluminate and Magnesiate Complexes as Propagating Species in the Anionic Polymerization of Styrene and Dienes

    MACROMOLECULAR SYMPOSIA, Issue 1 2004
    Alain Deffieux
    Abstract The influence of MgR2 and AlR3 additives on alkyllithium initiators in the anionic polymerization of butadiene has been investigated in non polar solvents. A strong decrease of the diene polymerization rate in the presence of the two Lewis acids was observed, similarly to that observed in the retarded anionic polymerisation of styrene. With n,s-Bu2Mg, the percentage of 1,2 vinyl units increases with the [Mg]/[Li] ratio. This behavior is specific to magnesium derivatives bearing secondary alkyl groups and likely results from the additional complexation of lithium species by free dialkylmagnesium and/or a 1,4- to 1,2- chain end isomerization process during chain exchanges between polybutadienyl active chains and dormant ones attached to magnesium species. These reversible exchanges also lead to the formation of one supplementary chain by initial dialkyl magnesium which acts as reversible chain transfer agent. On the contrary with the R3Al/RLi systems the number of chains is only determined by the concentration of initial alkyllithium and no modification of the polybutadiene microstructure compared to lithium initiators (1,4 units = 80%) is noticed. Dialkyl magnesiate complexes with alkali metal derivatives (i.e. alkoxide) are also able to influence the stereochemistry of the styrene insertion during the propagation reaction. Polystyrenes with different tacticities ranging from predominantly isotactic (85% triad iso) to syndiotactic (80% triad syndio) can be obtained with these initiators. [source]


    Design and Synthesis of Functionalized Styrene-Butadiene Copolymers by Means of Living Anionic Polymerization

    MACROMOLECULAR SYMPOSIA, Issue 1 2004
    Mayumi Hayashi
    Abstract Styrene-butadiene copolymers (SBR) end-functionalized with dimethylamino groups at the initiating and terminating chain-ends were successfully synthesized by a one-step methodology based on living anionic polymerization using 1-(4-dimethylaminophenyl)-1-phenylethylene. The expected structures of the resulting copolymers were confirmed by 1H-NMR, SEC, and SLS analyses, titration, and model reactions. Furthermore, the possible synthesis of tri-functionalized styrene-butadiene copolymer with dimethylamino groups in a chain by extending the methodology is described. [source]


    Preparation of isotactic-rich poly(dimethyl vinylphosphonate) and poly(vinylphosphonic acid) via the anionic polymerization of dimethyl vinylphosphonate

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2010
    Takehiro Kawauchi
    Abstract A vinylphosphonate monomer, dimethyl vinylphosphonate (DMVP), has been polymerized by anionic initiators. Anionic polymerization of DMVP with tert -butyllithium (t -BuLi) in combination with a Lewis acid, tributylaluminum (n -Bu3Al), in toluene proceeded smoothly to give an isotactic-rich poly(dimethyl vinylphosphonate) (PDMVP) with relatively narrow molecular weight distribution. Although all the PDMVPs were soluble in water, the isotactic-rich PDMVP was insoluble in acetone and in chloroform which are good solvents for an atactic PDMVP prepared by radical polymerization. The isotactic-rich PDMVP showed higher thermal property than that of the atactic PDMVP. Moreover, we successfully prepared poly(vinylphosphonic acid) (PVPA) through the hydrolysis of the isotactic-rich PDMVP, which formed a highly transparent, self-standing film. 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1677,1682, 2010 [source]


    Anionic polymerization of methyl methacrylate initiated with late transition-metal halides/organolithium/triisobutylaluminum systems

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2003
    Eiji Ihara
    Abstract Anionic polymerization of methyl methacrylate (MMA) initiated with late transition-metal halides [manganese chloride (MnCl2), iron dichloride (FeCl2), iron trichloride (FeCl3), cobalt chloride (CoCl2), or nickel bromide (NiBr2)]/organolithium [nButyllithium (nBuLi) or phenyllithium (PhLi)]/triisobutylaluminum (iBu3Al) systems is described. Except for the system with NiBr2, the polymerizations of MMA afforded narrow molecular weight distribution poly(methyl methacrylate)s (PMMAs) with high molecular weights in quantitative yields at 0 C in toluene. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses of the PMMAs obtained by the systems with FeCl2, FeCl3, and CoCl2 revealed that the polymers had hydrogen (H) at both chain ends. Accordingly, the reaction of the transition-metal halides with the organolithium in the presence of iBu3Al should result in the formation of transition-metal hydride [M-H], species, which was nucleophilic enough to initiate the MMA polymerization. Because the presence of a six-membered cyclic structure resulting from backbiting was confirmed from the MALDI-TOF MS analyses of the PMMA obtained with the metal halide (FeCl2, FeCl3, or CoCl2)/organolithium systems in the absence of iBu3Al, the introduction of H at the ,-chain end indicated that iBu3Al should prevent the backbiting. However, the MnCl2/nBuLi/iBu3Al initiating system gave PMMAs bearing H at the , chain end and six-membered cyclic structure at the , chain end. 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1962,1977, 2003 [source]


    Self-Supporting, Double Stimuli-Responsive Porous Membranes From Polystyrene- block -poly(N,N -dimethylaminoethyl methacrylate) Diblock Copolymers

    ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
    Felix Schacher
    Abstract Asymmetric membranes are prepared via the non-solvent-induced phase separation (NIPS) process from a polystyrene- block -poly(N,N -dimethylaminoethyl methacrylate) (PS- b -PDMAEMA) block copolymer. The polymer is prepared via sequential living anionic polymerization. Membrane surface and volume structures are characterized by scanning electron microscopy. Due to their asymmetric character, resulting in a thin separation layer with pores below 100,nm on top and a macroporous volume structure, the membranes are self-supporting. Furthermore, they exhibit a defect-free surface over several 100,m2. Polystyrene serves as the membrane matrix, whereas the pH- and temperature-sensitive minority block, PDMAEMA, renders the material double stimuli-responsive. Therefore, in terms of water flux, the membranes are able to react on two independently applicable stimuli, pH and temperature. Compared to the conditions where the lowest water flux is obtained, low temperature and pH, activation of both triggers results in a seven-fold permeability increase. The pore size distribution and the separation properties of the obtained membranes were tested through the pH-dependent filtration of silica particles with sizes of 12,100,nm. [source]


    Synthesis of Half-Channels by the Anionic Polymerization of Ethylene Oxide Initiated by Modified Cyclodextrin

    ADVANCED MATERIALS, Issue 40 2009
    Nezha Badi
    Amphiphilic star-shaped oligomers are produced by anionic polymerization of ethylene oxide (EO) using per-2,3-di- O -heptyl- , -(or ,)cyclodextrins as initiators , a versatile way of synthesizing artificial channels bearing one polyEO branch per glucose unit. The behavior of the amphiphilic molecules in lipid membranes is studied by electrical measurements, which confirms the formation of transient, well-defined dimeric ionic channels (see figure). [source]


    Structure of charge-transfer reaction complexes in anionic polymerization of isoprene: Quantum chemical calculations

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2005
    K. K. Kalninsh
    Abstract A new mechanism of isoprene anionic polymerization is proposed. Its central moment is thermal electronic excitation of a living polyisoprene,isoprene complex into the quasi-degenerate electronically excited state (S T)1, which is of the charge (electron) transfer character. It is asserted that the probability of chemical bond formation is determined by the free valence index on carbon atoms and by the geometry of reacting complex in the excited state (S T)1. Semi-empirical AM1 and ab initio 6-31G* quantum chemical calculations revealed low energies of triplet excited levels (<10 kcal/mole). Comparison of isoprene polymerization on free anions and on solvated ion pairs shows that both types of active centers produce vinyl 1,2 (4,3)-units. Free anions generate predominantly 1,2-units, whereas solvated ion pairs tend to form units with the 4,3-structure. Analysis of energies of excited isoprenyl lithium + isoprene complexes shows that the formation of 1,4 (4,1)- cis -polyisoprene in an inert media is most preferable. 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source]


    Effect of surfactant on fabrication and characterization of paclitaxel-loaded polybutylcyanoacrylate nanoparticulate delivery systems

    JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2003
    Amitava Mitra
    ABSTRACT The feasibility of applying biodegradable polybutylcyanoacrylate (PBCA) nanoparticulate delivery systems (NDSs) for the controlled release of paclitaxel was investigated. Paclitaxel-loaded and unloaded PBCA-NDSs containing various surfactants (dextran 70, cholesterol, polyvinyl alcohol and lecithin) were prepared by anionic polymerization. The effects of surfactant (1% w/v), surfactant combination (1% w/v each), and surfactant concentration (0.05, 1.0 and 2.5% w/v) on PBCA-NDSs were evaluated and characterized by particle size, zeta potential, entrapment efficiency, and in-vitro paclitaxel release kinetics. The physicochemical characteristics of PBCA-NDSs incorporated with various surfactants were significantly improved compared with PBCA-NDS without any surfactant, by decreasing particle size at least 3-fold as well as by increasing the zeta potential up to 18-fold to minimize the agglomeration of nanoparticles. Moreover, PBCA-NDSs incorporated with various surfactants demonstrated higher entrapment efficiency of paclitaxel. Results from the in-vitro release kinetic studies indicated that a more controlled biphasic zero-order release pattern of paclitaxel was observed for PBCA-NDSs incorporated with various surfactants. Compared with dextran 70 and polyvinyl alcohol, the naturally occurring lipids, lecithin and cholesterol, indicated greater advantages in improving the physicochemical properties of PBCA-NDSs, in terms of smaller particle size, higher zeta potential and better drug entrapment efficiency, and better controlled release of paclitaxel, in terms of lower release rate and prolonged action from PBCA-NDSs. [source]


    Thermoresponsive brush copolymers with poly(propylene oxide- ran -ethylene oxide) side chains via metal-free anionic polymerization "grafting from" technique

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2010
    Junpeng Zhao
    Abstract Thermoresponsive brush copolymers with poly(propylene oxide- ran -ethylene oxide) side chains were synthesized via a "grafting from" technique. Poly(p -hydroxystyrene) was used as the backbone, and the brush copolymers were prepared by random copolymerization of mixtures of oxyalkylene monomers, using metal-free anionic ring-opening polymerization, with the phosphazene base (t -BuP4) being the polymerization promoter. By controlling the monomer feed ratios in the graft copolymerization, two samples with the same side-chain length and different compositions were prepared, both of which possessed high molecular weights and low molecular weight distributions. The results from light scattering and fluorescence spectroscopy indicated that the brush copolymers in their dilute aqueous solutions were near completely solvated at low temperature and underwent slight intramolecular chain contraction/association and much more profound intermolecular aggregation at different stages of the step-by-step heating process. Above 50 C, very turbid solutions, followed by macrophase separation, were observed for both of the samples, which implied that it was difficult for the brush copolymers to form stable nanoscopic aggregates at high temperature. All these observations were attributed, at least partly, to the distribution of the oxyalkylene monomers along the side chains and the overall brush-like molecular architecture. 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2320,2328, 2010 [source]


    Preparation of isotactic-rich poly(dimethyl vinylphosphonate) and poly(vinylphosphonic acid) via the anionic polymerization of dimethyl vinylphosphonate

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2010
    Takehiro Kawauchi
    Abstract A vinylphosphonate monomer, dimethyl vinylphosphonate (DMVP), has been polymerized by anionic initiators. Anionic polymerization of DMVP with tert -butyllithium (t -BuLi) in combination with a Lewis acid, tributylaluminum (n -Bu3Al), in toluene proceeded smoothly to give an isotactic-rich poly(dimethyl vinylphosphonate) (PDMVP) with relatively narrow molecular weight distribution. Although all the PDMVPs were soluble in water, the isotactic-rich PDMVP was insoluble in acetone and in chloroform which are good solvents for an atactic PDMVP prepared by radical polymerization. The isotactic-rich PDMVP showed higher thermal property than that of the atactic PDMVP. Moreover, we successfully prepared poly(vinylphosphonic acid) (PVPA) through the hydrolysis of the isotactic-rich PDMVP, which formed a highly transparent, self-standing film. 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1677,1682, 2010 [source]


    Titanium-mediated [CpTiCl2(OEt)] ring-opening polymerization of lactides: A novel route to well-defined polylactide-based complex macromolecular architectures

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2010
    Nikolaos Petzetakis
    Abstract Among three cyclopentadienyl titanium complexes studied, CpTiCl2(OEt), containing a 5% excess CpTiCl3, has proven to be a very efficient catalyst for the ring-opening polymerization (ROP) of L -lactide (LLA) in toluene at 130 C. Kinetic studies revealed that the polymerization yield (up to 100%) and the molecular weight increase linearly with time, leading to well-defined PLLA with narrow molecular weight distributions (Mw/Mn , 1.1). Based on the above results, PS- b -PLLA, PI- b -PLLA, PEO- b -PLLA block copolymers, and a PS- b -PI- b -PLLA triblock terpolymer were synthesized. The synthetic strategy involved: (a) the preparation of OH-end-functionalized homopolymers or diblock copolymers by anionic polymerization, (b) the reaction of the OH-functionalized polymers with CpTiCl3 to give the corresponding Ti-macrocatalyst, and (c) the ROP of LLA to afford the final block copolymers. PMMA- g -PLLA [PMMA: poly(methyl methacrylate)] was also synthesized by: (a) the reaction of CpTiCl3 with 2-hydroxy ethyl methacrylate, HEMA, to give the Ti-HEMA-catalyst, (b) the ROP of LLA to afford a PLLA methacrylic-macromonomer, and (c) the copolymerization (conventional and ATRP) of the macromonomer with MMA to afford the final graft copolymer. Intermediate and final products were characterized by NMR spectroscopy and size exclusion chromatography, equipped with refractive index and two-angle laser light scattering detectors. 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1092,1103, 2010 [source]


    Asymmetric anionic polymerization of 7-cyano-7-ethoxycarbonyl-1,4-benzoquinone methide

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2009
    Noboru Nakagaki
    An optically active polymer having configurational chirality in the main chain was synthesized from a prochiral monomer, 7-cyano-7-ethoxycarbonyl-1,4-benzoquinone methide (1), by asymmetric anionic polymerization using various chiral anionic initiators. The effects of the chiral ligand and solvent polarity on the specific rotations of the resulting polymers were investigated. The polymerization of 1 using iPrPhOLi/(,)-PhBox complex initiator in a mixture solution of dichloromethane/toluene ratio of 30/70 (in vol %) at ,78 C afforded an optically active polymer with a large positive specific rotation ([,]435 = +90.4). [source]


    Controlled synthesis of poly(dimethylsiloxane) homopolymers using high-vacuum anionic polymerization techniques

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2009
    Mario D. Ninago
    Abstract The controlled synthesis of poly(dimethylsiloxane) homopolymers (PDMS) using hexamethyl(cyclotrisiloxane) monomer (D3), a mixture of ciclohexane/tetrahydrofuran 50/50 v/v and sec- Bu,Li+ as initiator was studied using different experimental conditions, and whole-sealed glass reactors according to standards procedures in high-vacuum anionic polymerization. It was observed that polydispersity indexes (PD) and conversions strongly depend on temperature and reaction times. For PDMS homopolymers with molar masses below 100,000 g/mol, high conversion (>90%) and PD < 1.1 can be achieved at long reaction times (24 h) and mild temperature conditions (below or up to 30 C). On the other hand, to synthesize PDMS homopolymers with molar masses higher than 100,000 g/mol and PD < 1.1 it is necessary to increase the temperature up to 50 C and decrease the reaction time (8 h). However, under these reaction conditions, it was observed that the conversion decreases (about 65,70% conversion is achieved). Apparently, the competition between propagation and secondary reactions (redistribution, backbiting, and reshuffling) depends on the molar masses desired. According to the results obtained in this study,which were compared with others found in the scientific literature,propagation is favored when Mn < 100,000 g/mol, whereas secondary reactions seem to become important for higher molar masses. Nevertheless, model PDMS homopolymers with high molar masses can still be obtained increasing the reaction temperature and shortening the total reaction time. It seems that the combined effect of these two facts favors propagation against secondary reactions, and provides model PDMS homopolymers with molar masses quite close to the expected ones. 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4774,4783, 2009 [source]


    Synthesis and degradation of biomedical materials based on linear and star shaped polyglycidols

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2009
    Helmut Keul
    Abstract Linear and star shaped polyglycidols (synonym with polyglycerols) are prepared in a controlled ring opening polymerization of protected glycidols. Beside the molar mass and the polydispersity, the architecture of the polyglycidols is controlled by using mono- and multifunctional mono- and polydispers initiators. Copolymers of dissimilarly protected glycidols as well as copolymers with nonfunctional oxiranes were prepared by means of anionic polymerization while copolymers of protected glycidol with tetrahydrofuran were prepared by means of cationic polymerization. Polyethers with functional groups in the side chains (functional polyethers) with special emphasis on polyglycidols (containing hydroxymethyl groups in the side chains) were used to prepare multifunctional polymers and (hetero)grafted polymer brushes via chemical and enzyme catalyzed reaction. The potential of poly(glycidol- graft -,-caprolactone)- co -glycidol) prepared via enzyme catalyzed grafting of polyglycidols using ,-caprolactone as a monomer and Lipase B from Candida antarctica as a catalyst is presented. Finally, comparative degradation studies of densely and loosely grafted polyglycidols are presented and discussed. 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3209,3231, 2009 [source]


    Ferrocenyl-functionalized long chain branched polydienes

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2009
    Frederik Wurm
    Abstract A convenient two-step approach for the synthesis of ferrocenyl-functionalized long chain branched polydienes, based on both butadiene and isoprene, respectively, is presented. Classical living anionic polymerization was used to synthesize different ABn type poly(diene) macromonomers with moderate molecular weights between 1700 and 3200 g/mol and narrow polydispersity. Quantitative end-capping with chlorodimethylsilane resulted in the desired ABn macromonomer structures. In the ensuing Pt-catalyzed hydrosilylation polyaddition, branched, functionalized polydienes were obtained by a concurrent ABn + AR type of copolymerization with mono- and difunctional ferrocenyl silanes (fcSiMe2H or fc2SiMeH). Molecular weights of the branched polymers were in the range of 10,000 to 44,000 g/mol (SEC/MALLS). Because of the large number of functional end groups, high loading with ferrocene units up to 63 wt % of ferrocene was achieved. Detailed studies showed full conversion of the functional silanes and incorporation into the branched polymer. Further studies using DSC, TGA, and cyclovoltammetry (CV) measurements have been performed. Electrochemical studies demonstrated different electrochemical properties for fcSiMe2 - and fc2SiMe-units. The CVs of polymers modified with diferrocenylsilane units exhibit the pattern of communicating ferrocenyl sites with two distinct, separate oxidation waves. The polymers were also deposited on an electrode surface and the electrodes investigated via CV, showing formation of electroactive films with promising results for the use of the materials in biosensors. 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2518,2529, 2009 [source]


    Well-defined complex macromolecular architectures by anionic polymerization of styrenic single and double homo/miktoarm star-tailed macromonomers

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2008
    Paraskevi Driva
    Abstract Styrenic single and double star-tailed macromonomers were synthesized by selective reaction of living homo/miktoarm stars with the chlorosilane groups of 4-(chlorodimethylsilyl)- and 4-(dichloromethylsilyl)styrene, respectively. The in situ anionic homopolymerization of macromonomers with sec -BuLi and copolymerization with butadiene and styrene, led to single/double homo/miktoarm star-tailed molecular brushes and combs, as well as a block copolymer consisting of a linear polystyrene chain and a double miktoarm (PBd/PS) star-tailed brush-like block. Molecular characterization by size exclusion chromatography, size exclusion chromatography/two-angle laser light scattering, and NMR spectroscopy, revealed the high molecular/compositional homogeneity of all intermediate and final products. These are only a few examples of the plethora of complex architectures possible using the above macromonomers. 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1826,1842, 2008 [source]


    Chain transfer to ionic liquid in an anionic polymerization of methyl methacrylate

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2007
    Tadeusz Biedro
    When methyl methacrylate is polymerized with alkyllithium as initiator in imidazolium ionic liquids, low molecular weight polymers are formed in high yield. The head-groups are, however, not those alkyl groups that are present in alkyllithium, but predominantly those that are originally present at 1-position in imidazolium cation indicating extensive chain transfer to imidazolium ionic liquid. [source]


    Precise synthesis of well-defined dendrimer-like star-branched polymers by iterative methodology based on living anionic polymerization

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2006
    Akira Hirao
    Abstract Dendrimer-like star-branched polymers recently developed as a new class of hyperbranched polymers, which resemble well-known dendrimers in branched architecture, but comprise polymer chains between junctions, are reviewed in this highlight article. In particular, we focus on the precise synthesis of various dendrimer-like star-branched polymers and block copolymers by the recently developed methodology based on iterative divergent approach using living anionic polymers and 1,1-bis(3- tert -butyldimethylsilyloxymethylphenyl)ethylene. 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6659,6687, 2006 [source]


    Synthesis of amphiphilic copolymer brushes: Poly(ethylene oxide)-graft-polystyrene

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2006
    Zhongyu Li
    Abstract A well-defined amphiphilic copolymer brush with poly(ethylene oxide) as the main chain and polystyrene as the side chain was successfully prepared by a combination of anionic polymerization and atom transfer radical polymerization (ATRP). The glycidol was first protected by ethyl vinyl ether to form 2,3-epoxypropyl-1-ethoxyethyl ether and then copolymerized with ethylene oxide by the initiation of a mixture of diphenylmethylpotassium and triethylene glycol to give the well-defined polymer poly(ethylene oxide- co -2,3-epoxypropyl-1-ethoxyethyl ether); the latter was hydrolyzed under acidic conditions, and then the recovered copolymer of ethylene oxide and glycidol {poly(ethylene oxide- co -glycidol) [poly(EO- co -Gly)]} with multiple pending hydroxymethyl groups was esterified with 2-bromoisobutyryl bromide to produce the macro-ATRP initiator [poly(EO- co -Gly)(ATRP). The latter was used to initiate the polymerization of styrene to form the amphiphilic copolymer brushes. The object products and intermediates were characterized with 1H NMR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, Fourier transform infrared, and size exclusion chromatography in detail. In all cases, the molecular weight distribution of the copolymer brushes was rather narrow (weight-average molecular weight/number-average molecular weight < 1.2), and the linear dependence of ln[M0]/[M] (where [M0] is the initial monomer concentration and [M] is the monomer concentration at a certain time) on time demonstrated that the styrene polymerization was well controlled. This method has universal significance for the preparation of copolymer brushes with hydrophilic poly(ethylene oxide) as the main chain. 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4361,4371, 2006 [source]


    Synthesis of silicon nitride based ceramic nanoparticles by the pyrolysis of silazane block copolymer micelles

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2006
    Kozo Matsumoto
    Abstract Diblock copolymer poly(1,1,3,N,N,-pentamethyl-3-vinylcyclodisilazane)- block- polystyrene (polyVSA- b -polySt) and triblock copolymer poly(1,1,3,N,N,-pentamethyl-3-vinylcyclodisilazane)- block- polystyrene- block -poly(1,1,3,N,N,-pentamethyl-3-vinylcyclodisilazane) (polyVSA- b -polySt- b -polyVSA), consisting of silazane and nonsilazane segments, were prepared by the living anionic polymerization of 1,1,3,N,N,-pentamethyl-3-vinylcyclodisilazane and styrene. PolyVSA- b -polySt formed micelles having a poly(1,1,3,N,N,-pentamethyl-3-vinylcyclodisilazane) (polyVSA) core in N,N -dimethylformamide, whereas polyVSA- b -polySt and polyVSA- b -polySt- b -polyVSA formed micelles having a polyVSA shell in n -heptane. The micelles with a polyVSA core were core-crosslinked by UV irradiation in the presence of diethoxyacetophenone as a photosensitizer, and the micelles with a polyVSA shell were shell-crosslinked by UV irradiation in the presence of diethoxyacetophenone and 1,6-hexanedithiol. These crosslinked micelles were pyrolyzed at 600 C in N2 to give spherical ceramic particles. The pyrolysis process was examined by thermogravimetry and thermogravimetry/mass spectrometry. The morphologies of the particles were analyzed by atomic force microscopy and transmission electron microscopy. The chemical composition of the pyrolysis products was analyzed by X-ray fluorescence spectroscopy and Raman scattering spectroscopy. 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4696,4707, 2006 [source]


    Preparation of novel poly(ethylene oxide- co -glycidol)-graft-poly(,-caprolactone) copolymers and inclusion complexation of the grafted chains with ,-cyclodextrin

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2006
    Juan Huang
    Abstract A well-defined comblike copolymer of poly(ethylene oxide- co -glycidol) [(poly(EO- co -Gly)] as the main chain and poly(,-caprolactone) (PCL) as the side chain was successfully prepared by the combination of anionic polymerization and ring-opening polymerization. The glycidol was protected by ethyl vinyl ether to form 2,3-epoxypropyl-1-ethoxyethyl ether (EPEE) first, and then ethylene oxide was copolymerized with EPEE by an anionic mechanism. The EPEE segments of the copolymer were deprotected by formic acid, and the glycidol segments of the copolymers were recovered after saponification. Poly(EO- co -Gly) with multihydroxyls was used further to initiate the ring-opening polymerization of ,-caprolactone in the presence of stannous octoate. When the grafted copolymer was mixed with ,-cyclodextrin, crystalline inclusion complexes (ICs) were formed, and the intermediate and final products, poly(ethylene oxide- co -glycidol)- graft -poly(,-caprolactone) and ICs, were characterized with gel permeation chromatography, NMR, differential scanning calorimetry, X-ray diffraction, and thermogravimetric analysis in detail. The obtained ICs had a channel-type crystalline structure, and the ratio of ,-caprolactone units to ,-cyclodextrin for the ICs was higher than 1:1. 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3684,3691, 2006 [source]


    Experimental techniques in high-vacuum anionic polymerization

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2005
    David Uhrig
    Abstract Experimental methods used in high-vacuum anionic polymerization are described in detail, with extensive illustrations to demonstrate proper procedures and techniques. These descriptions include construction and operation of the vacuum line, handling purification chemicals, ampulization techniques, short-path distillations, initiator synthesis, polymerization procedures, and linking reactions using chlorosilanes. A primary emphasis is placed on safety. We believe that this review of these methods will be useful to scientists working in the field of anionic polymerization and may also benefit other researchers in performing tasks requiring ultra-high-purity reaction conditions. 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6179,6222, 2005 [source]


    Synthesis and characterization of poly[styrene- b -methyl(3,3,3-trifluoropropyl)siloxane] diblock copolymers via anionic polymerization

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2005
    Lingmin Yi
    Abstract A series of narrow molecular weight distribution (MWD) polystyrene- b -poly[methyl(3,3,3-trifluoropropyl)siloxane] (PS- b -PMTFPS) diblock copolymers were synthesized by the sequential anionic polymerization of styrene and trans -1,3,5-trimethyl-1,3,5-tris(3,,3,,3,-trifluoropropyl)cyclotrisiloxane in tetrahydrofuran (THF) with n -butyllithium as the initiator. The diblock copolymers had narrow MWDs ranging from 1.06 to 1.20 and number-average molecular weights ranging from 8.2 103 to 37.1 103. To investigate the properties of the copolymers, diblock copolymers with different weight fractions of poly[methyl(3,3,3-trifluoropropyl)siloxane] (15.4,78.8 wt %) were prepared. The compositions of the diblock copolymers were calculated from the characteristic proton integrals of 1H NMR spectra. For the anionic ring-opening polymerization (ROP) of 1,3,5-trimethyl-1,3,5-tris(3,,3,,3,-trifluoropropyl)cyclotrisiloxane (F3) initiated by polystyryllithium, high monomer concentrations could give high polymer yields and good control of MWDs when THF was used as the polymerization solvent. It was speculated that good control of the block copolymerization under the condition of high monomer concentrations was due to the slowdown of the anionic ROP rate of F3 and the steric hindrance of the polystyrene precursors. There was enough time to terminate the ROP of F3 when the polymer yield was high, and good control of block copolymerization could be achieved thereafter. The thermal properties (differential scanning calorimetry and thermogravimetric analysis) were also investigated for the PS- b -PMTFPS diblock copolymers. 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4431,4438, 2005 [source]


    First diphosphinoamine ligand bearing a polymerizable side chain: Complexation with copper(I)

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2005
    Ritu Ahuja
    Abstract A diphosphinoamine ligand with a polymerizable side chain, (PPh2)2NCH2C6H4CHCH2 (vbzpnp or 1), was synthesized. The ligand could be polymerized by anionic polymerization with n -butyllithium as the initiator. Polyvbzpnp was soluble in tetrahydrofuran and chloroform but was insoluble in methanol and was characterized with NMR, IR, and gel permeation chromatography. The number-average and weight-average molecular weights were 40,050 and 55,690, respectively, and the polydispersity index was 1.39. [Cu(CH3CN)4]ClO4 formed a bischelated complex with the monomer and produced [Cu(1)2]ClO4 (2), and CuCl formed a tetramer, Cu4(1)2Cl4 (3). All the compounds (1, 2, and 3) were characterized with single-crystal-structure determination, NMR, and IR spectroscopy. The addition of [Cu(CH3CN)4]ClO4 to polyvbzpnp resulted in an insoluble crosslinked polymer, which was characterized with solid-state 31P {1H} magic-angle-spinning NMR. The copolymerization of styrene and 1 produced a styrene,vbzpnp copolymer that was found to be soluble in common organic solvents. 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3411,3420, 2005 [source]