Preparation of highly syndiotactic block copolymers of methyl methacrylate and lauryl methacrylate and their characterization

Summary Highly syndiotactic diblock and triblock copolymers comprising lauryl methacrylate (LMA) and methyl methacrylate (MMA) with narrow molecular weight distributions were prepared by the living anionic polymerization with t-C₄H₉Li/(C₂H₅)₃Al in toluene at low temperature. The block copolymers were soluble in acetone which is a non-solvent for poly(lauryl methacrylate) (PLMA). ¹HNMR and vapor pressure osmometric analyses of the block copolymers indicated the aggregation of the copolymer in acetone through the interaction between PLMA blocks. Stereocomplex formation between the triblock copolymer and isotactic poly(methyl methacrylate) (PMMA) took place more effectively in solution than in the solid state.     

Stereoregular polymerization of polysiobutylene macromonomer having methacryloyl function

Summary The polysiobutylene (PIB) macromonomer having methacryloyl function was prepared from a hydroxy-terminated PIB, -phenyl--(2-hydroxy-1-methylethyl)-poly(1,1-dimethylethylene) and methacryloyl chloride in the presence of triethylamine. The macromonomer was polymerized by various anionic initiators to form stereoregular polymacromonomers. The polymerization of the macromonomer with t-C₄H₉MgBr and n-C₄H₉Li in toluene gave isotactic polymacromonomers. On the other hand, syndiotactic-rich polymacromonomers were obtained in the polymerizations with 1,1-diphenylhexyllithium in tetrahydrofuran and with t-C₄H₉Li/(C₂H₅)₃Al in toluene.     

Neutral Pd(II) and Ni(II) Acetylide Catalysts for the Polymerization of Methyl Methacrylate

Homogenous polymerization of methyl methacrylate using Pd(II)- and Ni(II)-based acetylide complexes as initiators has been investigated. M(PR'₃)₂(CCR)₂ (M=Pd, Ni; R'=PPh₃, Pn-Bu₃; R=Ph, CH₂OH, CH₂OOCCH₃, CH₂OOCPh, CH₂OOCPhOH-o) were found to be a novel type of effective initiators for the polymerization of methyl methacrylate. Among them, Pd(C CPh)₂(PPh₃)₂ (PPP) shows the highest activity in the MMA polymerization and the PMMA obtained is a syndiotactic polymer with high number-average molecular weight (M _n) of 14.1 × 10⁴. Some features and kinetic behavior of MMA polymerization initiated by PPP were studied in detail. The polymerization reaction is first-order with respect to both [PPP] and [MMA]. Radical polymerization mechanism is proposed.     

Lanthanide(II) amide complexes: Efficient initiators for the living polymerization of methyl methacrylate

Lanthanide(II) complexes supported by amido ligands, [(C₆H₅)(Me₃Si)N]₂Ln(DME)₂ [Ln = Sm ( 1 ) or Yb ( 2 ); DME = 1,2‐dimethoxyethane] and [(C₆H₃? ⁱPr₂‐2,6)(Me₃Si)N]₂Ln(THF)₂ [Ln = Sm ( 3 ) or Yb ( 4 ); THF = tetrahydrofuran], were found to initiate the polymerization of methyl methacrylate (MMA) as efficient single‐component initiators (in toluene for 3 and 4 and in toluene with a small amount of THF for 1 and 2 ) to produce syndiotactic polymers. The catalytic behavior was highly dependent on both the amido ligand and the polymerization temperature. Initiators 3 and 4 initiated MMA polymerization over a wide range of temperatures (20°C to ?40°C), whereas the polymerization with 1 and 2 proceeded smoothly only at low temperatures (≤0°C). The kinetic behavior and some features of the polymerizations of MMA initiated by 3 and 4 were studied at ?40°C. The polymerization rate was first‐order with the monomer concentration. The molar masses of the polymers increased linearly with the increase in the polymer yields, whereas the molar mass distributions remained narrow and unchanged throughout the polymerization; this indicated that these systems had living character. A polymerization mechanism initiated by bimetallic bisenolate formed in situ was proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Photopolymerization of methyl methacrylate and 2-(dimethylamino) ethyl methacrylate induced by diacetoxyiodobenzene in the presence of radical inhibitors

Summary Polyvalent iodine compounds such as diacetoxyiodobenzene, (CH₃COO)₂IC₆H₅ (DAI), and bis(trifluoroacetoxy) iodobenzene, (CF₃COO)₂IC₆H₅ (BTI), are efficient initiators of cationic and radical polymerizations. To confirm the radical mechanism of DAI-induced polymerization of methyl methacrylate (MMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA), a study has been performed in the presence of the radical inhibitor 2,3,5,6-tetrachloro-p-benzoquinone (TCQ) and its complex with triethylamine (TEA). The polymerization kinetics and the effect of irradiation intensity have been studied.     

Studies of a Supported Titanium Catalyst System Using Magnesium Dichloride–Alcohol Adduct

Magnesium dichloride reacts with aliphatic alcohols [ROH; R = n-C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉, i-C₄H₉, t-C₄H₉, n-C₅H₁₁, n-C₆H₁₃, C₆H₁₂(C₂H₅)] to form well-defined solid adducts. Compositional analysis of adducts indicates that the stoichiometric ratio of magnesium dichloride to alcohol depends on length of alkyl group and nature of isomeric alcohol. Magnesium dichloride-2-ethyl-l-hexanol adduct was treated with diphenyldichlorosilane in the presence of dibutylphthalate to obtain active magnesium dichloride support. The titanation process of active magnesium dichloride gives supported magnesium–titanium catalyst (Mg–Ti). The catalyst was characterized by compositional analysis and specific surface area measurements. Performance of the catalyst for polymerization of propene was evaluated with triethylaluminum (TEAL) and phenyltriethoxysilane (PES) as cocatalyst. The yield and isotacticity of the polymer is governed by polymerization parameters such as Si/A1 ratio and polymerization time.     

Synthesis and polymerization of liquid crystalline α-oxiranes containing 4-cyanobiphenyl andp-methoxyphenyl benzoate mesogenic groups

Summary The synthesis of a new series of -oxiranes containing 4-cyanobiphenyl andp-methoxyphenyl benzoate mesogenic groups and the phase behaviour of synthesized compounds are described. Polymerization of -oxiranes with BF₃.O(C₂H_{5 2}) and Et₃Al/H₂O/Acetyl acetone as initiators was carried out. The first initiator produced oligomers displaying liquid crystalline properties while the second gave crystalline polymers with a high degree of polymerization.     

Ethylene polymerization by phenylenedimethylene‐bridged homobinuclear zirconocene/methylaluminoxane systems

In the presence of methylaluminoxane (MAO), ethylene polymerization was successfully performed with homobinuclear zirconocene complexes {[(C₅H₅)ZrCl₂](C₅H₄CH₂ C₆H₄CH₂C₅H₄)[(C₅H₅)ZrCl₂]; 3o , 4m , and 5p }, which were prepared conveniently by the reaction of disodium(phenylenedimethylene)dicyclopentadienide [C₆H₄(CH₂C₅H₄Na)₂] with 2 equiv of (N⁵‐Cyclopentadienyl)trichlorozirconium dimethoxyethane (CpZrCl₃(DME)) in tetrahydrofuran and characterized by ¹H‐NMR and elemental analysis. The effects of the polymerization parameters, such as the temperature, time, concentration of the catalyst, MAO/catalyst molar ratio, and isomeric difference of the homobinuclear metallocene complexes 3o , 4m , and 5p were studied in detail. The results showed that all three catalytic systems had moderate activities in ethylene polymerization and afforded polyethylene with relatively broad polydispersities. The catalytic activity of 4m was somewhat higher than that of 3o and 5p but lower than that of 4,4′‐bis(methylene)biphenylene‐bridged zirconocene catalysts; this indicated that the distance between the two metal centers was too short in comparison with a 4,4′‐bis(methylene)biphenylene bridge to increase the catalytic activity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Cationic ring-opening polymerization of 2-phenyl-1,2-oxaphospholane (deoxophostone)

Summary The ring-opening polymerization of deoxophostone 5, a five-membered cyclic phosphinite, has been studied. Some cationic initiators gave polymer whereas anionic and radical initiators as well as metal chloride (Lewis acid) catalysts did not yield polymer. The polymer consisted of a phosphine oxide repeating unit 6. The polymerization proceeded via the Arbuzov-type reaction. The reduction of polymer 6 with a HSiCl₃/Et₃N system gave polyphosphine 7.     

Characterization of the anionic polymerization of 2-(ethoxy)ethyl methacrylate by t-C4H9MgBr in toluene

Anionic polymerizations of 2-(ethoxy)ethyl methacrylate (EOEMA) were carried out under several conditions that allowed for living polymerization of methyl methacrylate (MMA). It was found that the polymerization rate of EOEMA by t-C₄H₉MgBr in toluene was much lower than that of MMA under these conditions. However, the polymerization rate of EOEMA by t-C₄H₉MgBr in tetrahydrofuran was not much lower than the polymerization of MMA. Interactions between the counter cation (magnesium) and the ether oxygen of the ester moiety in the EOEMA unit are considered important to delay the polymerization. Random and block copolymerizations of EOEMA and MMA by t-C₄H₉MgBr in toluene were also carried out and the results support the interaction of ether oxygen. 4-(Ethoxy)butyl methacrylate (EOBMA) was successfully prepared from 4-ethoxy-1-butanol and methacryloyl chloride and purified. Polymerization of EOBMA with t-C₄H₉MgBr in toluene provides a polymer with good yield, suggesting that the number of carbon atoms between the ester group and the ether oxygen is important to the interactions with the ether oxygen. Some of the thermal properties of the polymers and copolymers, including their glass transition temperature and thermal stability, were also evaluated.     

Preparation of poly(methyl methacrylate) by ATRP using initiators for continuous activator regeneration (ICAR) in ionic liquid/microemulsions

In this study, we reported the synthesis of poly(methyl methacrylate) (PMMA) polymers via initiators for continuous activator regeneration atom transfer radical polymerization using CCl₄ as initiator, FeCl₃·6H₂O/hexamethylene tetramine as catalyst complex, and 2,2′-azobis(isobutyronitrile) (AIBN) as reducing agent. The polymerization was conducted at 60 °C in the ionic liquid based microemulsion with hexadecyl trimethyl ammonium bromide (CTAB) as surfactant. Kinetics experimental results showed that the polymerization proceeded in a controlled/‘living’ process. The effects of the molar ratio of [CCl₄]/[FeCl₃·6H₂O], the concentration of AIBN, temperature and the concentration of CTAB on the polymerization was investigated. The effect of CTAB concentration on the resulting PMMA particle size was also investigated. The obtained polymer was characterized by proton nuclear magnetic resonance and gel permeation chromatography. The living characteristics were demonstrated by chain extension experiment.     

Ethylene polymerization by 3‐oxa‐pentamethylene bridged asymmetric dinuclear titanocene/MAO system

An asymmetric 3‐oxa‐pentamethylene bridged dinuclear titanocenium complex (CpTiCl₂)₂(η⁵‐η⁵‐C₉H₆(CH₂CH₂OCH₂CH₂)C₅H₄) ( 1 ) has been prepared by treating two equivalents of CpTiCl₃ with the corresponding dilithium salts of the ligand C₉H₇(CH₂CH₂OCH₂ CH₂)C₅H₅. The complex 1 was characterized by ¹H‐, ¹³C‐NMR, and elemental analysis. Homogenous ethylene polymerization catalyzed using complex 1 has been conducted in the presence of methylaluminoxane (MAO). The influences ofreaction parameters, such as [MAO]/[Cat] molar ratio, catalyst concentration, ethylene pressure, temperature, and time have been studied in detail. The results show that the catalytic activity and the molecular weight (MW) of polyethylene produced by 1 /MAO decrease gradually with increasing the catalyst concentration or polymerization temperature. The most important feature of this catalytic system is the molecular weight distribution (MWD) of polyethylene reaching 12.4, which is higher than using common mononuclear metallocenes, as well as asymmetric dinuclear titanocene complexes like [(CpTiCl₂)₂(η⁵‐η⁵‐C₉H₆(CH₂)_nC₅H₄)] (n = 3, MWD = 7.31; n = 4, MWD = 6.91). The melting point of polyethylene is higher than 135°C, indicating highly linear and highly crystalline polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Temperature effect on ethylene polymerization with a catalyst prepared by mixing Mg(C2H5)(n-C4H9), Al(C2H5)1.5Cl1.5 and iron(II)bis (imino)pyridyl complex

Summary Ethylene polymerization was conducted with a catalyst prepared by mixing 2,6-bis{1-[2,6-(diisopropylphenyl)imino]ethyl}pyridine iron dichloride, Mg(C₂H₅)(n-C₄H₉) and Al(C₂H₅)_1.5Cl_1.5 in the presence of common alkylaluminium as cocatalyst. Both the activity and the molecular weight of polymers produced were markedly dependent upon the polymerization temperature. The end-group analysis of polymers showed that the molecular weight of polymers produced at higher temperature was reduced by chain transfer with Al(C₂H₅)₃ in addition to β-hydrogen elimination.     

Studies on the preparation and properties of some Cyclopontadienyl and Indenyl Compounds of Molybdenum(VI)

Tetracyclopentadienyl molybdenum(VI) oxide, (C₅H₅)₄MoO 1 and tetraindenyl molybdenum(VI) oxide, (C₉H₇)₄MoO 2 have been prepared by the interaction of (C₅H₅)₂MoOCl₂ 3 or (C₉H₇)₂MoOCl₂ 4 with sodium cyclopentadienide and sodium indenide, respectively. 1 and 2 have been alternatively prepared by the reaction of molybdenum oxide tetrachloride with sodium cyclopentadienide or sodium indenide respectively. Phenoxides of 3 and 4 have also been prepared. I. R. spectra and some other physical characteristics of all these compounds are reported.     

Electroinitiated polymerization of benzonitrile

Summary The electroinitiated polymerization of benzonitrile yields a linear conjugated polymer, {ie421-01}(C₆H₅)C=N{ie421-02}. An anionic mechanism of polymerization is indicated.     

Magnetic composites obtainment based on styrene polymers

Three styrene‐based matrices for hybrid composites with ferrite have been obtained by emulsion polymerization in the presence of a tensioactive system: sodium n‐dodecylbenzene sulfate (C₁₂H₂₅C₆H₄SO₃Na) as anionic agent and poly(oxyethylene) nonylphenyl ether [C₉H₁₉C₆H₄(OCH₂CH₂)₃₀OH] as nonionic tensioactive agent. The system assures the steadiness of the emulsion during the reaction and the stability of the latices. The surfactants act as a protective colloid component and thickening agents determining an optimum viscosity and conditions for the further catching of the inorganic oxide with magnetic properties. The obtained polystyrene and styrene copolymers with acrylamide and methacrylamide were analyzed by elemental analysis, IR spectroscopy, DSC, and their viscosity data have been characterized. The size as well as the magnetic properties of composites were also appreciated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4133–4141, 2006     

Synthesis of atactic polypropylene: Propylene polymerization reactions with TiCl4–Al(C2H5)2Cl/Mg(C4H9)2 catalyst

The Ziegler catalyst, a combination of TiCl₄ and Al(C₂H₅)₂Cl, is a very poor catalyst for propylene polymerization. However, the addition of Mg(C₄H₉)₂ to the Ziegler catalyst at a [Mg]:[Al] molar ratio < 0.5 leads to the formation of a potent catalyst system for homopolymerization of propylene. Polymers produced with the TiCl₄–Al(C₂H₅)₂Cl/Mg(C₄H₉)₂ catalyst are mostly atactic and amorphous, their minor partially crystalline isotactic components constitute merely 5–10% of the combined polymer material. Principal advantages of the TiCl₄–Al(C₂H₅)₂Cl/Mg(C₄H₉)₂ catalyst for the manufacture of atactic PP include high activity, low cost, and the ease of use: the catalyst is prepared in situ from three commercially available components. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47692.     

Reactivity of cyclosiloxane with 3,3,4,4,5,5,6,6,6‐nonafluorohexyl group and its application to fluorosilicone synthesis

The reactivity of cyclosiloxane with 3,3,4,4,5,5,6,6,6‐nonafluorohexyl group and its application to fluorosilicone synthesis were studied. In contrast to the polymerization of the commercially available 1,3,5‐tris(3,3,3‐trifluoropropyl)‐1,3,5‐trimethylcyclotrisiloxane (CF₃–D3), the polymerization of 1,3,5‐tris(3,3,4,4,5,5,6,6,6‐nonafluorohexyl)‐1,3,5‐trimethylcyclotrisiloxane (C₄F₉–D3) with sodium hydroxide yielded 1,3,5,7‐tetrakis(3,3,4,4,5,5,6,6,6‐nonafluorohexyl)‐1,3,5,7‐tetramethylcyclotetrasiloxane {[C₄F₉CH₂CH₂(CH₃)SiO]₄ (C₄F₉–D4)} as the major product, which was the result of the depolymerization by a backbiting mechanism. On the other hand, the polymerization of C₄F₉–D3 with trifluoromethanesulfonic acid yielded a polymer with good reproducibility, although the distribution of molecular weight tended to be bimodal. C₄F₉–D3 was also successfully copolymerized with octamethylcyclotetrasiloxane (D4). The properties of the obtained copolymers changed almost linearly with the amount of [C₄F₉C₂H₄(CH₃)SiO] units, except for the surface tension. The surface tension of the copolymer containing more than 50% [C₄F₉C₂H₄(CH₃)SiO] units by weight was almost as low as that of the homopolymer. When the copolymer containing 50% [C₄F₉C₂H₄(CH₃)SiO] units by weight was examined for an antifoaming agent, it worked as effectively as the homopolymer in the toluene foaming system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3333–3340, 2001     

Elektrisch leitfähige polymerfilme, 1. 1,2-di-(N-n-alkyl-pyridinium-4)-ethylen-TCNQ-komplexe für elektrisch leitfähige polymerfilme: Darstellung und eigenschaften

In preparing polymer films doped with electrically conducting 7,7,8,8-tetracyanoquinodimethane-(TCNQ)-complexes, one of the requirements is an adequate solubility of these complexes. The solubility of the 1,2-di-(N-methyl-pyridinium-4)-ethylene-TCNQ-complex could be improved by a systematic extension of N-alkyl-chains though partly at the expense of stability and electrical conductivity. In addition to its sufficient conductivity and solubility, the 1,2-di-(N-n-propyl-pyridinium-4)-ethylene-TCNQ-complex was surprisingly found to display an unexpected thermal stability. Preparation and important properties (solubility in N-methyl pyrrolidone (NMP), electrical conductivity, thermal stability) of the complexes with alkyl- = ? CH₃, ? C₂H₅, -n-C₆H₁₃, -n-C₈H₁₇ (TCNQ-content: 4 moles) and with alkyl- = -n-C₃H₇, -n- C₄H₉, -n-C₅H₁₁ (TCNQ-content: 5 moles) are reported.     

Effect of carrier nature and monomer pressure on polymerization of ethylene with high activity catalyst system

Summary The effects of monomer pressure, texture of amorphous SiO₂ carrier used and stoichiometry of surface titanium complexes on the profile of the kinetic curves obtained by polymerization of ethylene with high activity catalyst system TiCl₄/SiO₂-(C₂H₅)₂AlCl-(C₄H₉)_1.5(C₈H₁₇)_0.5Mg were studied. It was found that constant polymerization rate was reached for different times but their values did not depend on pressure and carrier used. The results obtained suggest that surface complexes with mole ratio Cl⁻/Ti⁴⁺=2 generate higher number of active centers and higher polymerization rate. A relationship between kinetic studies and productivity, microstructure of polymers synthesized and their physico-mechanical properties is shown. Received: 2 November 1999/Revised version: 8 February 2000/Accepted: 8 February 2000