HELVETICA CHIMICA ACTA, Issue 2 2005
Antonella Leone
New Cs -symmetric aryl 1,4-diphosphine ligands were synthesized and tested in the copolymerization of carbon monoxide and propene. The electronic properties of the two different P-atoms did not affect the high enantioselectivity of the catalyst precursors, thus resulting in high ,regio'- and ,stereoregular' copolymers. [source]

Copolymerization of n -butylacrylate with methylmethacrylate by a novel photoinitiator, 1-(bromoacetyl)pyrene

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2007
Anuradha Mishra
The photopolymerization efficiency of pyrene (Py), 1-acetylpyrene (AP), and 1-(bromoacetyl)pyrene (BP) for copolymerization of n -butylacrylate (BA) with methylmethacrylate (MMA) was compared. A kinetic study of solution copolymerization in DMSO at 30 ± 0.2°C showed that the Py could not initiate copolymerization even after 20 h, whereas with AP as initiator, less than 1% conversion was observed. However, introduction of a Br in ,-methyl group of AP significantly enhanced the percent conversion. The kinetics and mechanism of copolymerization of BA with MMA using BP as photoinitiator have been studied in detail. The system follows nonideal kinetics (Rp,, [BP]0.67[BA]1[MMA]0.98), and degradative solvent transfer reasonably explains these kinetic nonidealities. The monomer reactivity ratios (MRRs) of MMA and BA have been estimated by the Finemann,Ross and Kelen,Tudos methods, by analyzing copolymer compositions determined by 1H-NMR spectra. The values of r1 (MMA) and r2 (BA) were found to be 2.17 and 0.44, respectively, which suggested the high concentration of alternating sequences in the random copolymers obtained. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 261,267, 2007 [source]

Cover Picture: Multipotent Polymer Coatings Based on Chemical Vapor Deposition Copolymerization (Adv. Mater.

ADVANCED MATERIALS, Issue 12 2006
12/2006)
Abstract The cover shows that chemical vapor deposition can be used to prepare copolymer thin films, on varying substrates, that can bind two different ligands with high selectivity. In work reported by Lahann and co-workers on p.,1521, the actual ligand ratios on the surface can be controlled by varying the copolymer composition. This technology may find applications in biomedical devices, high-throughput screening platforms, microfluidic analysis devices, and diagnostic platforms. [source]

Facile, Efficient Copolymerization of Ethylene with Bicyclic, Non-Conjugated Dienes by Titanium Complexes Bearing Bis(,-Enaminoketonato) Ligands

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009
Jing-yu Liu
Abstract Copolymerizations of ethylene with 5-vinyl-2-norbornene or 5-ethylidene-2-norbornene under the action of various titanium complexes bearing bis(,-enaminoketonato) chelate ligands of the type, [R1NC(R2)CHC(R3)O]2TiCl2 (1, R1=Ph, R2=CF3, R3=Ph; 2, R1=C6H4F- p, R2=CF3, R3=Ph; 3, R1=Ph, R2=CF3, R3=t- Bu; 4, R1=C6H4F- p, R2=CF3, R3=t- Bu; 5, R1=Ph, R2=CH3, R3=CF3; 6, R1=C6H4F- p, R2=CH3, R3=CF3), have been shown to occur with the regioselective insertion of the endocyclic double bond of the monomer into the copolymer chain, leaving the exocyclic vinyl double bond as a pendant unsaturation. The ligand modification strongly affects the copolymerization behaviour. High catalytic activities and efficient co-monomer incorporation can be easily obtained by optimizing the catalyst structures and polymerization conditions. [source]

Alternating Copolymerization of Cyclohexene Oxide and CO2 Catalyzed by Zinc Complexes with New 3-Amino-2-cyanoimidoacrylate Ligands

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2005
Mario Kröger
Abstract New 3-amino-2-cyanoimidoacrylate ligands with varying steric demands have been synthesized. Zinc acetate complexes of these ligands catalyze the copolymerisation of CO2 and cyclohexene oxide, showing high activities (TOF up to over 200,h,1). [source]

Ethylene/,-olefin copolymerization using diphenylcyclopentadienyl-phenoxytitanium dichloride/Al(iBu)3/[Ph3C][B(C6F5)4] catalyst systems

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
Hongchun Li
Abstract Copolymerization of ethylene with 1-octene and 1-octadecene using constrained geometry catalysts 2-(3,4-diphenylcyclopentadienyl)-4,6-di- tert -butylphenoxytitanium dichloride (1), 2-(3,4-diphenylcyclopentadienyl)-6- tert -butylphenoxytitanium dichloride (2), 2-(3,4-diphenylcyclopentadienyl)-6-methylphenoxytitanium dichloride (3), and 2-(3,4-diphenylcyclopentadienyl)-6-phenylphenoxytitanium dichloride (4) was studied in the presence of Al(iBu)3 and [Ph3C][B(C6F5)4](TIBA/B). The effect of the catalyst structure, comonomer, and reaction conditions on the catalytic activity, comonomer incorporation, and molecular weight of the produced copolymers was also examined. The 1/TIBA/B catalyst system exhibits high catalytic activity and produces high molecular weight copolymers. The melting temperature and the degree of crystallinity of the copolymers show a decrease with the increase in the comonomer incorporation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Synthesis, characterization, and antimicrobial properties of novel quaternary amine methacrylate copolymers

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
Supriya Punyani
Abstract A novel amine methacrylate monomer trimethylolpropane trimethacrylate,piperazine,ethyleneglycol dimethacrylate (TMPTMA-PPZ-EGDMA) was synthesized by amination of trimethylolpropane trimethacrylate (TMPTMA) with excess of piperazine (PPZ) followed by reaction with ethyleneglycol dimethacrylate (EGDMA). Copolymerization of TMPTMA-PPZ-EGDMA with 2-hydroxyethyl methacrylate (HEMA) was carried out by free radical polymerization using ammonium persulfate (APS) and N,N,N,,N,-tetramethyl ethylenediamine (TEMED) as a redox initiator. The copolymers obtained were then quaternized with 1-iodooctane. The monomers were characterized by FTIR and 1H NMR spectral studies. The molecular weights and polydispersity values of the monomers were determined with gel permeation chromatography. Quaternized copolymers containing more than 20% amine methacrylate monomer showed microporosity in the range of 9.9,10.4 ,m. The antibacterial activity of the quaternized copolymers against Escherichia coli and Staphylococcus aureus was studied using UV,vis spectrophotometer and scanning electron microscopy. Quaternized copolymers showed broad-spectrum contact-killing antibacterial properties without releasing any active agent as checked by iodide selective ion meter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Copolymerization of carbon dioxide and propylene oxide with zinc glutarate as catalyst in the presence of compounds containing active hydrogen

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007
L. J. Gao
Abstract To enhance the catalytic copolymerization of CO2 and propylene oxide catalyzed by zinc glutarate, the influence of trace of water, ethanol, and propanal on the catalytic activity, the resulted copolymer structure, and the molecular weight and molecular weight distribution of the copolymer were investigated extensively. The experimental results showed that the catalytic activity decreased remarkably in the presence of either trace of ethanol or water, but increased in the presence of trace of propanal. Both 1H-NMR and 13C-NMR spectra suggested that the content of carbonate linkages of resulted copolymer was not effected obviously in the presence of above-mentioned impurities, giving completely alternating poly(propylene carbonate) (PPC). GPC results indicated that these impurities reduced the molecular weights but broadened the molecular weight distributions of resulted copolymers. Finally, the byproduct contents including both propylene carbonate determined by GC and polyether increased with the increase of three impurity concentrations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Copolymerization of D,L -lactide and glycolide in supercritical carbon dioxide with zinc octoate as catalyst

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008
Rosario Mazarro
Abstract The objective of the study is the development of a new technique based on supercritical technology for the production of bioabsorbable polymeric microparticles containing pharmaceutical principles, for their use in the controlled release of medicines. For this purpose, the ring-opening copolymerization of D,L -lactide and glycolide in supercritical carbon dioxide, using zinc(II) 2-ethylhexanoate (ZnOct2) as catalyst, was studied. The polymer obtained with ZnOct2 has similar characteristics to that obtained with stannous octoate (SnOct2), the conventional catalyst used up to now for this kind of polymerization process. Experiments were performed at various reaction times, pressures, and stirring rates. The most outstanding result was found by varying the stirring rate, where particles forming agglomerates seem to be obtained at the greater agitation levels. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source]

Copolymerization of amino acid and amino ester functionalized norbornenes via living ring-opening metathesis polymerization

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2008
Stefano C. G. Biagini
Abstract The block and random copolymerization of a series of amino acid and amino ester functionalized norbornenes by ring-opening metathesis polymerization (ROMP) induced by the well-defined molybdenum [Mo(N -2,6- iPrC6H3)(CHCMe2)Ph)(OCMe3)2] or ruthenium [Ru(PCy)2Cl2(CHPh)] based initiators is described. The monomers are derived from the amino acids glycine, alanine, and isoleucine or the methyl esters of these amino acids and either endo- or exo- norborn-5-ene-2,3-dicarboxylic anhydride. Enantiomerically pure monomers afforded optically active polymers, and the mechanism and kinetics of the copolymerizations are investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7985,7995, 2008 [source]

Dispersion polymerization of vinyl monomers in supercritical carbon dioxide in the presence of drug molecules: A one-pot route for the preparation of controlled delivery systems

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2008
Alessandro Galia
Abstract The polymerization of 1-vinyl-2-pyrrolidone in supercritical carbon dioxide in the presence of ibuprofen as a model drug was investigated as a new one-pot process for the preparation of polymer-based drug delivery systems (DDSs). The composites were prepared at 65 °C and P = 31,42 MPa by changing the initial concentration of the drug and the concentration of a crosslinking agent and that of a hydrophobic comonomer. The effects of these parameters on the performances of the polymerization and on the in vitro release kinetics of ibuprofen were studied. In all the experiments, part of the drug was entrapped inside the polymer particles and dissolved more slowly with respect to the pure compound. Copolymerization with methyl methacrylate was the most effective route to obtain a DDS with sustained temporal release of the drug molecule. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7429,7446, 2008 [source]

Copolymerization of vinyl acetate with 1-octene and ethylene by cobalt-mediated radical polymerization

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2007
Rayna Bryaskova
Abstract The cobalt-mediated radical polymerization of vinyl acetate was extended to copolymerization with 1-alkenes (ethylene or 1-octene). In agreement with the low amount of 1-alkene that could be incorporated into the copolymer, a gradient structure was predictable, but a rather low polydispersity was observed. A poly(vinyl acetate)- b -poly(octene) copolymer was also successfully synthesized, leading to a poly (vinyl alcohol)- b -poly(octene) amphiphilic copolymer upon the methanolysis of the poly (vinyl acetate) block. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2532,2542, 2007 [source]

Copolymerization of vinylcyclohexane with ethene and propene using zirconocene catalysts

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2006
Erkki Aitola
Abstract Vinylcyclohexane (VCH) was copolymerized with ethene and propene using methylaluminoxane-activated metallocene catalysts. The catalyst precursor for the ethene copolymerization was rac -ethylenebis(indenyl)ZrCl2 (1). Propene copolymerizations were further studied with Cs -symmetric isopropylidene(cyclopentadienyl)(fluorenyl)ZrCl2 (2), C1 -symmetric ethylene(1-indenyl-2-phenyl-2-fluorenyl)ZrCl2 (3), and "meso"-dimethylsilyl[3-benzylindenyl)(2-methylbenz[e]indenyl)]ZrCl2 (4). Catalyst 1 produced a random ethene,VCH copolymer with very high activity and moderate VCH incorporation. The highest comonomer content in the copolymer was 3.5 mol %. Catalysts 1 and 4 produced poly(propene- co -vinylcyclohexane) with moderate to good activities [up to 4900 and 15,400 kg of polymer/(mol of catalyst × h) for 1 and 4, respectively] under similar reaction conditions but with fairly low comonomer contents (up to 1.0 and 2.0% for 1 and 4, respectively). Catalysts 2 and 3, both bearing a fluorenyl moiety, gave propene,VCH copolymers with only negligible amounts of the comonomer. The homopolymerization of VCH was performed with 1 as a reference, and low-molar-mass isotactic polyvinylcyclohexane with a low activity was obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6569,6574, 2006 [source]

Copolymerization of norbornene and styrene catalyzed by a novel anilido,imino nickel complex/methylaluminoxane system

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2006
Haiyang Gao
Abstract Copolymerizations of norbornene with styrene were carried out with a catalytic system of anilido,imino nickel complex (ArNCHC6H4NAr)NiBr (Ar = 2,6-dimethylphenyl) and methylaluminoxane in toluene. The influence of the comonomer feed content and polymerization temperature on the conversion and composition of the copolymers with (ArNCHC6H4NAr)NiBr/methylaluminoxane was investigated. An increase in the initial styrene feed content led to an increase in the incorporated styrene content of the resulting copolymer. The determination of the reactivity ratios showed a much high reactivity for norbornene (reactivity ratio for styrene = 0.26, reactivity ratio for norbornene = 20.78), which was consistent with a coordination mechanism. NMR analysis of the end groups further confirmed that the chain was initiated through a styrene secondary insertion or a norbornene insertion into NiH and terminated through ,-H elimination from an inserted styrene unit. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5237,5246, 2006 [source]

Copolymerization of poly(vinyl alcohol)- graft -poly(1,4-dioxan-2-one) with designed molecular structure by a solid-state polymerization method

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2006
Si-Chong Chen
Abstract Poly(vinyl alcohol)- graft -poly(1,4-dioxan-2-one) (PVA- g -PPDO) with designed molecular structure was synthesized by a solid-state polymerization. The solid-state copolymerization was preceded by a graft copolymerization of PDO initiated with PVA as a multifunctional initiator, and Sn (Oct)2 as a coininitiator/catalyst in a homogeneous molten state. The polymerization temperature was then decreased and the copolymerization was carried out in a solid state. The products prepared by solid-state polymerization were characterized by 1H NMR and DSC, and were compared with those synthesized in the homogeneous molten state. The degree of polymerization (Dp), degree of substitution (Ds), yield and the average molecular weight of the graft copolymer with different molecular structure were calculated from the 1H NMR spectra. The results show that the crystallization process during the solid-state polymerization may suppress the undesirable inter- or intramolecular side reactions, then resulting in a controlled molecular structure of PVA- g -PPDO. The results of DSC measurement show that the molecular structures determine the thermal behavior of the PVA- g -PPDO. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3083,3091, 2006 [source]

Copolymerization of ethylene with styrene catalyzed by a linked bis(phenolato) titanium catalyst

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2006
Carmine Capacchione
Abstract Copolymerization of ethylene with styrene, catalyzed by 1,4-dithiabutanediyl-linked bis(phenolato) titanium complex and methylaluminoxane, produced exclusively ethylene,styrene copolymers with high activity. Copolymerization parameters were calculated to be rE = 1.2 for ethylene and rS = 0.031 for styrene, with rErS = 0.037 indicating preference for alternating copolymerization. The copolymer microstructure can be varied by changing the ratio between the monomers in the copolymerization feed, affording copolymers with styrene content up to 68%. The copolymer microstructure was fully elucidated by 13C NMR spectroscopy revealing, in the copolymers with styrene content higher than 50%, the presence of long styrene,styrene homosequences, occasionally interrupted by isolated ethylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1908,1913, 2006 [source]

Copolymerization of vinylidene difluoride with hexafluoropropene in supercritical carbon dioxide

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2006
Uwe Beginn
Abstract Vinylidene difluoride and hexafluoropropene are copolymerized in supercritical carbon dioxide at 280 bar and 50 °C by means of free radical copolymerization, initiated by diethyl peroxydicarbonate. The first stages of the reaction were monitored by turbidity measurements and the time/conversion curve was followed gravimetrically to measure the initial rates of polymerization. The obtained copolymers possessed bimodal molecular weight distributions, their average comonomer composition was well described by the Lewis-Mayo equation with the copolymerization parameters rVDF = 4.8 and rHFP = 0. The glass transition and melting temperatures of the copolymers are similar to that of the materials resulting from aqueous emulsion polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1299,1316, 2006 [source]

Copolymerization of ethylene and N -(vinylphenyl)carbazole with titanium and zirconium catalysts

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2005
Naofumi Naga
Copolymerization of ethylene and N -(vinylphenyl)carbazole (VPC) was investigated with dimethylsilylene(tetramethylcyclopentadienyl)(N-tert -butyl)titanium dichloride (1) and isopropylidenebis(indenyl)zirconium dichloride (2) catalysts. The corresponding copolymers were obtained in the copolymerization, and the copolymerization behavior and structure of the resulting copolymer were studied. [source]

Copolymerization of carbon dioxide and epoxide

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2004
Hiroshi Sugimoto
Abstract An erratum has been published for this article in J Polym Sci Part A: Polym Chem (2005) 43(4) 916. The alternating copolymerization of carbon dioxide and epoxide to produce polycarbonate has attracted the attention of many chemists because it is one of the most promising methodologies for the utilization of carbon dioxide as a safe, clean, and abundant raw material in synthetic chemistry. Recent development of catalysts for alternating copolymerization is based on the rational design of metal complexes, particularly complexes of transition metals with well-defined structures. In this article, the history and recent successful examples of the alternating copolymerization of carbon dioxide and epoxide are described. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5561,5573, 2004 [source]

Copolymerization of ethylene with 1-hexene over metallocene catalyst supported on complex of magnesium chloride with tetrahydrofuran

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2004
Krystyna Czaja
Abstract The study of ethylene/1-hexene copolymerization with the zirconocene catalyst, bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2)/methylaluminoxane (MAO), anchored on a MgCl2(THF)2 support was carried out. The influence of 1-hexene concentration in the feed on catalyst productivity and comonomer reactivity as well as other properties was investigated. Additionally, the effect of support modification by the organoaluminum compounds [(MAO, trimethlaluminum (AlMe3), or diethylaluminum chloride (Et2AlCl)] on the behavior of the MgCl2(THF)2/Cp2ZrCl2/MAO catalyst in the copolymerization process and on the properties of the copolymers was explored. Immobilization of the Cp2ZrCl2 compound on the complex magnesium support MgCl2(THF)2 resulted in an effective system for the copolymerization of ethylene with 1-hexene. The modification of the support as well as the kind of organoaluminum compound used as a modifier influenced the activity of the examined catalyst system. Additionally, the profitable influence of immobilization of the homogeneous catalyst as well as modification of the support applied on the molecular weight and molecular weight distribution of the copolymers was established. Finally, with the successive self-nucleation/annealing procedure, the copolymers obtained over both homogeneous and heterogeneous metallocene catalysts were heterogeneous with respect to their chemical composition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2512,2519, 2004 [source]

Copolymerization of diglycidyl ether of bisphenol A with ,-butyrolactone catalyzed by ytterbium triflate: Shrinkage during curing

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2003
Cristina Mas
Abstract Diglycidyl ether of bisphenol A (DGEBA) was cured with ,-butyrolactone (,-BL) with ytterbium triflate as a catalyst. The curing was studied with differential scanning calorimetry, Fourier transform infrared (FTIR), and thermomechanical analysis. FTIR studies confirmed that four elemental reactions took place during the curing process: the formation of a spiroorthoester (SOE) by the reaction of DGEBA with ,-BL, the homopolymerization of SOE, the homopolymerization of DGEBA, and the copolymerization of SOE and DGEBA. Moderate proportions of ,-BL produced materials with higher glass-transition temperatures, and the curing occurred with lower shrinkage after gelation because of the polymerization of SOE, with near-zero shrinkage during the final stages of the curing. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2794,2808, 2003 [source]

Copolymerization of (2-phenyl-1,3-dioxolane-4-yl)methyl methacrylate with alkyl methacrylates: Reactivity ratios and copolymer characterization

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2002
Mehmet Co
Abstract The radical copolymerizations of (2-phenyl-1,3-dioxolane-4-yl-)methyl methacrylate (PDMMA) with methyl methacrylate (MMA), ethyl methacrylate (EMA), and butyl methacrylate (BMA) were studied in dioxane at 60 °C with benzoyl peroxide as an initiator. The glass-transition temperatures of poly(PDMMA- co -MMA), poly(PDMMA- co -EMA), and poly(PDMMA- co -BMA) varied from 130 to 138 °C, from 100 to 134 °C, and from 63 to 122 °C, respectively, depending on the copolymer composition. Along with some physicochemical properties and thermal stability investigations of the copolymers, the monomer reactivity ratios were also determined with the conventional Finemann,Ross and Kelen,Tüdös linearization methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1184,1191, 2002 [source]

Copolymerization of propylene with various higher ,-olefins using silica-supported rac -Me2Si(Ind)2ZrCl2

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2001
Jun-Ting Xu
Abstract The copolymerization of propylene with 1-hexene, 1-octene, 1-decene, and 1-dodecene was carried out with silica-supported rac -Me2Si(Ind)2ZrCl2 as a catalyst. The copolymerization activities of the homogeneous and supported catalysts and the microstructures of the resulting copolymers were compared. The activity of the supported catalyst was only one-half to one-eighth of that of the homogeneous catalyst, depending on the comonomer type. The supported catalyst copolymerized more comonomer into the polymer chain than the homogeneous catalyst at the same monomer feed ratio. Data of reactivity ratios showed that the depression in the activity of propylene instead of an enhancement in the activity of olefinic comonomer was responsible for this phenomenon. We also found that copolymerization with ,-olefins and supporting the metallocene on a carrier improved the stereoregularity and regioregularity of the copolymers. The melting temperature of all the copolymers decreased linearly with growing comonomer content, regardless of the comonomer type and catalyst system. Low mobility of the propagation chain in the supported catalyst was suggested as the reason for the different polymerization behaviors of the supported catalyst with the homogeneous system. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3294,3303, 2001 [source]

Preparation and Biodegradation of Sugar-Containing Poly(vinyl acetate) Emulsions

MACROMOLECULAR BIOSCIENCE, Issue 2 2008
Akinori Takasu
Abstract To accelerate the biodegradability of poly(vinyl acetate)-based emulsions, emulsion copolymerizations of vinyl sugars, including triacetylated N -acetyl- D -glucosamine (GlcNAc)-substituted 2-hydroxyethyl methacrylate (GlcNAc(Ac)3 -substituted HEMA), glucose-substituted HEMA (GEMA) and 6- O -vinyladipoyl- D -glucose (6- O -VAG) with vinyl acetate (VAc), were carried out using poly(vinyl alcohol) as an emulsifying agent in the presence of poly[(butylene succinate)- co -(butylene adipate)] [poly(BS- co -BA)]. Copolymerization with GEMA produced a stable emulsion and that with 6- O -VAG also produced a homogeneous emulsion. Their biodegradation tests indicated that PVAc main chain scission was accelerated by copolymerization with vinyl sugars. [source]

Lactic Acid-Based Functionalized Polymers via Copolymerization and Chemical Modification

MACROMOLECULAR BIOSCIENCE, Issue 3 2004
Benjamin Saulnier
Abstract Summary: Poly(lactic acid) polymers (PLA) are presently the most attractive compounds in the field of artificial degradable and biodegradable polymers. In order to enlarge the family, and thus the range of accessible properties, stereocopolymers and copolymers with various co-monomers have been synthesized. However, very few are functionalized, i.e. include functional groups attached to the main chains or as part of the side chains. In the search for degradable PLA-type polymers bearing functional groups to serve as intermediates for further chemical modifications, we are exploring two different routes. The first one is copolymerization with a protected hydroxyl-bearing lactide-type monomer, namely 3-(1,2,3,4-tetraoxobutyldiisopropylidene)dioxane-2,5-dione. The second route consists of the formation of a carbanionic site in the , -position to intrachain carbonyl functions by using lithium N,N -diisopropylamide followed by the coupling of electrophiles. Recent advances in this search are presented using several examples. In particular, it is shown that OH-functionalized PLA-type macromolecules can be made fluorescent by chemical coupling. It is also shown that substituents can be attached to PLA-type macromolecules in solution or to the surface of PLA-based devices selectively. Example of chemical modifications of hydroxyl-bearing PLA-type polymers derived from gluconic and glycolic acids (via gluconolactone) and lactic acid (via lactide). [source]

Efficient Molecular Weight Control with Trialkylaluminum in Ethylene/Norbornene Copolymerization by [Ph2C(Flu)(3-MeCp)]ZrCl2/Methylaluminoxane Catalyst

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19 2010
Tomoyuki Tada
Abstract Ethylene/norbornene copolymerizations were conducted with [Ph2C(Flu)(3-RCp)]ZrCl2 [R: Me (1) or Me3Si (2)], which give alternating EN copolymers. The activity of 1 in the absence of R3Al was approximately twice that of 2 and increased further upon addition of R3Al. Et3Al increased the activity most effectively, and the of the produced polymer decreased from 100 000 to 25 000,g,·,mol,1. On the other hand, the value increased upon addition of iBu3Al from 100 000 to 209 000,g,·,mol,1 accompanied by an ,2.5-fold increase of activity. Consequently, 1 was found to be one of the most promising complexes for the synthesis of alternating EN copolymers, of which value was efficiently controlled by the kind and the amount of R3Al added. [source]

Facile Synthesis of Spherical Polyelectrolyte Brushes as Carriers for Conducting Polymers to be Used in Plastic Electronics

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 18 2009
Jianjun Wang
Abstract A two-step method for the preparation of spherical polyelectrolyte brushes (SPBs) has been developed. Copolymerization of styrene and divinyl benzene at the particle surface resulted in a large number of accessible vinyl groups. These vinyl groups reacted with sodium styrene sulfonate to give SPBs. The SPBs were used as carriers for conducting polymers resulting in redispersible conducting inks with good film forming properties. Direct current (DC) conductivity of the polypyrrole (PPy) loaded samples showed a percolating behavior as probed by impedance spectroscopy. Finally, device performance of organic light-emitting diodes based on the conducting thin films assembled from the PPy loaded particles was tested. [source]

Alternating Copolymerization of Carbon Dioxide and Propylene Oxide Catalyzed by Cobalt Schiff Base Complex

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2009
Yongsheng Niu
Abstract Cobalt 2,4-dinitrophenolate (complex 1) based upon a N,N,O,O -tetradentate Schiff base ligand framework was prepared. X-ray diffraction analysis confirmed that complex 1 was triclinic species with a six-coordinated central cobalt octahedron in the solid. Asymmetric alternating copolymerization of carbon dioxide (CO2) with racemic propylene oxide (rac -PO) proceeded effectively by complex 1 in conjunction with (4-dimethylamino)pyridine (DMAP), yielding a perfectly alternating and bimodal molecular weight distribution PO/CO2 poly(propylene carbonate) (PPC) with a small amount of cyclic carbonate byproducts. [source]

Free Radical Graft Copolymerization of Methyl Methacrylate onto Polyolefin Backbone: Kinetics Modeling through Model Compounds Approach

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13-14 2009
Thierry Badel
Abstract The grafting of poly(methyl methacrylate) (PMMA) from poly[ethylene- co -(1-octene)] in the molten state by in situ radical polymerization of methyl methacrylate (MMA) was investigated through a kinetic modeling using a model compound approach. We resorted to pentadecane (C15H32) and 2,6,10,15,19,23-hexamethyltetracosane (Squalane, C30H62) as models for both the copolymer ethylene and octene moieties. The attention was focused on the simulation of MMA conversion and PMMA average polymerization degree according to temperature, reaction time, and initiator ratio required for the polymerization of MMA in the presence of alkoxyl radicals and alkanes. [source]

Copolymerization of Ethylene with 2,7-Octadienyl Methyl Ether in the Presence of Metallocene and Nickel Diimine Catalysts

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2009
Mércia Fernandes
Abstract In this work, copolymers of ethylene with 2,7-octadienyl methyl ether have been synthesized in the presence of three single-site catalysts. The obtained copolymers not only have a polar ether function but also a double bond in the side chains that is useful for secondary reactions. The polymers were characterized by GPC, EA, DSC, NMR, and FT-IR. The catalytic activity depends on the kind of catalysts, the concentration of the polar monomer, and the concentration of the protecting agent. Up to 7.3 wt.-% of MODE could be incorporated by the metallocene catalyst. These are in average 120 functional side groups in a polymer molecule with a molecular mass of 230,000. [source]