Vinyl polymerization by metal complexes. XVI. Photopolymerization of vinyl monomers by metal-amine systems

The photopolymerization of vinyl monomers was studied by the system of metal-amine complex and carbon tetrachloride. Addition of amines to the initiating system generally accelerates the polymerization. The acceleration by various sorts of amines in different solvents was examined. It was confirmed that the photopolymerization in question is of free radical character. The polymerization mechanism was discussed.     

Oxidative polymerization of 2,6-dimethylphenol catalyzed by copper-mixed amine system

Summary Copper-mixed n-butylamine /dibutylamine complex was used as the catalyst for 2,6-dimethylphenol polymerization. The effects of several variables such as copper salts, additives, reaction temperature and pressure, and amine/copper ratio on the catalyst performance were studied. The catalyst activity was found to be highly dependent on the specific combination of copper salts and amines, and copper iodide-amine complex showed an unusual long induction period. Polymer molecular weight was sensitive to the addition of methanol and surfactant, reaction temperature and amine/copper ratio but insensitive to the pressure. Initial polymerization rate was strongly affected by reaction pressure.     

Mechanism research of copper(II)-catalyzed polymerization of 2,4,6-trichlorophenols

The copper(II)-catalyzed polymerization of 2,4,6-trichlorophenol and 2,4,6-trichloro-3-methylphenol were studied. Their polymer structures were confirmed by elemental analysis, infrared (IR), and nuclear magnetic resonance (NMR). The 2,4,6-trichlorophenoxo–copper(II) complex and 2,4,6-trichloro-3-methylphenoxo–copper(II) complex intermediates were isolated. The elemental analysis and electron spin resonance (ESR) measurement of the phenoxo–copper(II) complexes were discussed in relation to their structures. Decomposition of the phenoxo–copper(II) complex in refluxing benzene yielded poly(dichlorophenylene oxide). ESR measurements on the phenoxo–copper(II) complex in the solid state at 120°C indicated that the phenoxy radical was generated during the period of decomposition and the intensity of the ESR spectra based on the copper(II) ion decreased with the measurement time. A single-electron transfer reaction mechanism was proposed for the phenoxo–copper(II) complex intermediate. © 1996 John Wiley & Sons, Inc.     

Vinyl polymerization by metal complexes, 26. Vinyl polymerization initiated by polyvinylamine-copper(II) chelate in dimethylsulfoxide solution

The polymerization of acrylonitrile and methyl methacrylate initiated by polyvinylamine-copper(II) chelate was studied in dimethylsulfoxide solution, in the presence and absence of carbon tetrachloride. For comparison, the dimeric chelate(1,3-diaminopropane-copper(II) chelate) was also chosen as an initiator. The initiation activity of the dimeric chelate was found to be higher than that of the polymeric chelate in dimethylsulfoxide solution, different from the cases in aqueous media. The dimeric chelate could initiate the polymerization of acrylonitrile effectively, even in the absence of carbon tetrachloride.     

Cationic polymerization using allyl sulfonium salt. 3. Allyl sulfonium salt/ascorbate redox couple

The cationic polymerization of cyclohexene oxide was initiated by reduction of allyl sulfonium salt in the presence of ascorbyl-6 hexadecanoate and copper (II) benzoate. A redox reaction in which the copper compound serving as an electron carrier for the initiation step was proposed.     

Atom transfer radical polymerization of n‐butyl methacrylate in an aqueous dispersed system

Atom transfer radical polymerization of n‐butyl methacrylate (BMA) was conducted in an aqueous dispersed system with different kinds of copper complexes. The partitioning behavior of the copper complexes, including CuCl/4,4′‐di(5‐nonyl)‐2,2′‐bipydine (dNbpy), CuCl₂/dNbpy, CuCl/2,2′‐bipydine (bpy), CuCl₂/bpy, CuCl/bis(N,N′‐dimethylaminoethyl)ether (bde), and CuCl₂/bde between the monomer (BMA), and water was studied in detail with ultraviolet‐visible spectroscopy. The results show that with a less hydrophobic ligand, such as bpy or bde, most of the Cu(I) or the Cu(II) complexes migrated from the BMA phase to the aqueous phase, the atom transfer equilibrium was destroyed, and the polymerization was nearly not controlled; it converted to classical emulsion polymerization. As to the very hydrophobic ligand dNbpy, although the partitioning study of the copper complexes indicated that not all the copper species were restricted to the organic phase, the linear correlation between the molecular weight and the monomer conversion and the narrow polydispersities confirmed that the polymerization was still quite well controlled. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3175–3179, 2003     

Vinyl polymerization by metal complexes. XVIII. Kinetics of the polymerization of acrylonitrile initiated by imidazole-copper-(II) complexes

A study on the kinetics and mechanism of the polymerization of acrylonitrile initiated by imidazole and 2-substituted imidazole-copper-(II) complexes was made in dimethyl sulfoxide solution at 40–70°C. The rate of polymerization, Rp, could be expressed as follows: The overall activation energies of these polymerization processes are in a range from 14.2 to 69.1 KJ mole^-1. From the data of electronic spectra and electron paramagnetic resonance, it was confirmed that the polymerization in question could be initiated by free radicals which were formed by the reduction of copper-(II) complex to copper-(I) complex, and the latter formed a new complex with polyacrylonitrile resulted.     

Controllable ring‐opening polymerization of trimethylene carbonate catalyzed by aliphatic tertiary amines in the presence of benzyl alcohol or F127

With the increased awareness of avoiding residue metals, the field of organocatalysts is attracting more attention. Aliphatic tertiary amines, such as triethylamine (TEA), N, N, N, N‐tetramethylethylenediamine (TMEDA) and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDTA), have low boiling points which allow their easy elimination after a chemical reaction. Here, we used these aliphatic tertiary amines to catalyze ring‐opening polymerizations (ROPs) of trimethylene carbonate (TMC). In the presence of benzyl alcohol, the catalytic activities of the tertiary amines were in the order of TEA < TMEDA < PMDTA. Correlation between the molecular weight of polycarbonates and monomer conversions was linear, suggesting the polymerization was controlled. The polymerization pathway was presumed to follow an alcohol‐activated mechanism according to the end‐group fidelity determined using ¹H NMR spectroscopy. The ROP of TMC was also successfully initiated by PEO₉₉‐PPO₆₅‐PEO₉₉ (F127) under the catalysis of the tertiary amines, producing well‐defined PTMC_n‐F127‐PTMC_n copolymers with narrow dispersity ( ca 1.2) and with thermosensitive properties in aqueous solution. Furthermore, copolymerizations of TMC with acryloyl‐containing cyclic carbonate were catalyzed by the tertiary amines in the presence of F127. No crosslinking reactions were detected. Our results demonstrate that the aliphatic tertiary amines have the potential to catalyze TMC homo‐ or copolymerization featuring controllable structure and composition under mild conditions. Copyright © 2012 Society of Chemical Industry     

Controlled polymerization of 2,3,5,6-tetrafluorophenyl methacrylate

Well-defined homopolymer of 2,3,5,6-tetrafluorophenyl methacrylate (TFPM) was successfully synthesized via atom transfer radical polymerization (ATRP) technique. Controlled polymerization was achieved with the addition of CuBr₂ as deactivator, which decreased the reaction rate and minimized the premature termination. The controlled/“living” polymerization behavior was supported by kinetic studies and the full chain extension for block copolymerization with 2-(dimethylamino) ethyl methacrylate (DMAEMA). Poly(TFPM) is an useful precursor for poly(methacrylamides) library syntheses. The active ester groups reacted with a variety of amines to produce a range of well-defined poly(methacrylamides), some of which would have been difficult to obtain by direct polymerizations of the methacrylamide monomers. Complete conversion to poly(methacrylamide) was achieved with unhindered primary amines. Substitution reactions with aromatic amines such as aniline did not occur under normal reaction conditions.     

Protective flexible coatings on copper by spontaneous polymerization

Spontaneous polymerization (S‐Poly) is a novel process for forming protective polymer coatings on metals. The S‐Poly mechanism on copper is discussed for one typical monomer system. Poly(ethylene glycol) ethyl ether methacrylate (EEM), a flexible monomer, was first introduced into a styrene/N‐phenyl maleimide system that we had used for aluminum and steel. The effects of EEM on the composition, apparent molecular weight, thermal properties, and other properties of the coatings were studied with reflectance Fourier transform infrared, gel permeation chromatography, differential scanning calorimetry, and water‐uptake and adhesion experiments. N‐(4‐Fluorophenyl) maleimide (4FMI), a strongly hydrophobic monomer, was further incorporated into the EEM copolymer for improved water impermeability. The resultant coatings, which included EEM and 4FMI units, showed good bonding strength to copper and better ductility and protective properties than other coatings in both corrosion and pinhole tests. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1749–1757, 2002     

Diffusion-controlled semibatch emulsion polymerization of styrene

Semibatch emulsion polymerization of styrene under the monomer-starved condition is strongly affected by the gel effect. A mechanistic model based on diffusion-controlled reaction mechanisms is developed to predict the kinetics of semibatch emulsion polymerization. Experimental data available in the literature are employed to assess the proposed model. Reasonable agreement between the model predictions and experimental data is observed. The simulation results suggest that the reaction system approaches Smith–Ewart case II kinetics (n? = 0.5) when the concentration of monomer in the particles is close to the saturation value, whereas the reaction system under the monomer-starved condition is characterized by diffusion-limited reaction mechanisms (n?≥0.5). © 1995 John Wiley & Sons, Inc.     

The Mechanism of Copper(II)-catalysed Polymerization of 2,4,6-Tribromophenols

The copper(II )-catalysed polymerization of 2,4,6-tribromophenol and 2,4,6-tribromo-3-methylphenol by homogeneous and heterogeneous reaction was studied. The dependence of polymer yield and molecular weight on reaction time was investigated. The variance of bromide ion concentration in the polymerization mixture was measured continuously by a bromide ion selective electrode. The existence of phenoxy radical during the homogeneous polymerization process was confirmed by electron spin resonance measurements. A quinol ether equilibrium polymerization mechanism was proposed for the copper(II)-catalysed homogeneous polymerization of 2,4,6-tribromophenols. © of SCI.     

Role of chiral amine cocatalysts in the helix-sense-selective polymerization of a phenylacetylene using a catalytic system

We have examined the role of the chiral amine cocatalyst in the recently discovered helix-sense-selective polymerization of a phenylacetylene using a catalytic system consisting of an achiral rhodium complex ([Rh(norbornadiene)Cl]₂) as the catalyst and a chiral amine as the cocatalyst. Several chiral amines were effective for the polymerization reaction and their effectiveness depended on their bulkiness and coordination ability to rhodium. The sense selectivity of the polymerization increased with the concentration of the chiral amines. To discuss the structure of the true active species in the catalytic system, we have synthesized a new chiral rhodium complex having two chiral amines as ligands ([Rh(norbornadiene)(chiral amine)₂]⁺BF₄⁻). The isolated chiral complex also catalyzed the helix-sense-selective polymerization. These findings suggest that a chiral rhodium complex having two chiral amines may be the true active species when using the catalytic system consisting of [Rh(norbornadiene)Cl]₂ and a chiral amine.     

Reversible addition-fragmentation chain transfer polymerization of styrene initiated by tetraethylthiuram disulfide

The RAFT polymerization of styrene in bulk was carried out using tetraethylthiuram disulfide (TETD) as an initiator and 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as a chain transfer agent at different temperatures. The results of the polymerization showed that TETD could initiate the RAFT polymerization of styrene in the living way. The kinetics of the polymerization showed first order. The molecular weights of the polymers increased linearly with conversions and were close to the theoretical values (M_n,th). The polydispersities of the polymers remained relatively narrow (<1.3). The structure of the polymer was characterized by ¹H NMR. The result showed that there were moieties of CPDN and TETD attained at the end of the polymer. Using these double functional end capped polymers, the chain-extension experiments were successfully carried out not only in the conventional RAFT polymerization way, but also under UV irradiation.     

Aerobic oxidative polymerization of 2,6‐dimethylphenol in water with a highly efficient copper(II)– poly(N‐vinylimidazole) complex catalyst

A Cu(II)–poly(N‐vinylimidazole) (PVI) complex was prepared and used to catalyze the oxidative polymerization of 2,6‐dimethylphenol (DMP) to form poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) in water. The stoichiometric ratio between imidazole groups in PVI and copper ions was found to be 4 when continuous variation analysis was applied. Compared with a conventional Cu(II)–low‐molecular‐weight ligand complex, a high catalytic efficiency was observed in the polymerization of DMP catalyzed by the Cu(II)–PVI complex. The influence of the Cu(II)–PVI complex concentration and imidazole/Cu(II) molar ratio on the oxidative polymerization of DMP was studied. Both the yield and molecular weight of PPO increased significantly with the catalyst concentration and decreased with the imidazole/Cu(II) molar ratio. The molecular weight of PVI also played an important role in the improvement of the catalytic efficiency. The high catalytic efficiency of the Cu(II)–PVI complex may have been due to the concentration effect of the catalyst and substrate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Introduction of quaternary amines onto a film surface by graft polymerization

Quaternary amines were introduced onto a poly(ethylene terephthalate) (PET) film surface by two different methods using UV-induced graft polymerization. The first involves a two-step reaction: graft polymerization of N,N′-(dimethylamino)ethyl methacrylate (DMAEMA) onto the PET film, followed by quaternization of the tertiary N,N′-dimethylamino groups of grafted chains using alkyl bromides (R_nBr). The second is direct graft polymerization of DMAEMA having pendant quaternary amines onto the PET film. The alkyl bromides used for quaternization of the monomers and graft chains include: n-propyl, n-butyl, n-octyl, n-lauryl, and n-cetyl bromide. The two-step method could quaternarize 90% of the pendant N,N′-dimethylamino groups of the graft chains when R₃Br was used. The extent of quaternization decreased with the increasing carbon number of alkyl bromide. The direct one-step method gave a graft amine density of 8 nmol/cm² when the monomer quaternized with R₃Br was used for the graft polymerization in the presence of 1 X 10^-3M sodium metaperiodate. The carbon number of alkyl chains in the quaternary amines estimated from XPS spectra was in good agreement with that of R_nBr used for quaternization. © 1996 John Wiley & Sons, Inc.     

Preparation of reverse osmosis membranes by plasma polymerization of organic compounds

The plasma polymerization of organic compounds was used to prepare a composite reverse osmosis membrane which consists of an ultrathin semipermeable membrane formed by plasma polymerization of an organic compound or compounds and a porous substrate. Many nitrogen-containing compounds (aromatic amines, heteroaromatic compounds, aliphatic amines, and nitriles) were found to yield excellent reverse osmosis membranes by plasma polymerization directly onto porous substrates such as Millipore filters, porous polysulfone filters, and porous glass tubes. Factors involved in the preparation of reverse osmosis membranes by plasma polymerization were investigated and discussed. The plasma polymerized membranes have the following unique features: (1) very stable performance independent of salt concentration and applied pressure (practically no water flux decline was observed with many membranes): (2) salt rejection and water flux both increase with time in the initial stage of reverse osmosis (consequently, the performance of the membrane improves with time of operation); (3) very high salt rejection (over 99%) with high water flux (up to 38 gfd) can be obtained with 3.5% NaCl at 1500 psi (membranes perform equally well under conditions of sea water conversion and brakish water treatment).     

Mechanistic and kinetic investigation of Cu(II)-catalyzed controlled radical polymerization enabled by ultrasound irradiation

Controlled radical polymerization (CRP) under external field has been an attractive research area in these years. In this work, a new electron transfer mechanism, that is, sonochemically induced electron transfer (SET) was introduced to mediate polymerization for the first time. The activator Cu^IX/L complex was (re)generated from Cu^IIX₂/L in dimethylsulfoxide (DMSO) by the SET process in the presence of free ligand tris(2-dimethylaminoethyl)amine (Me₆TREN). The investigation of polymerization including the mechanistic insights and effect of experimental conditions on the rate of reaction has been undertaken. Kinetics of Cu(II)-catalyzed CRPs via SET under different conditions (i.e., Me₆TREN concentration, catalyst loading, targeted degree of polymerization, and sonication power) were conducted in an unprecedentedly controlled manner, yielding polymers with predetermined molar masses and low dispersities (Đ < 1.12). Attractively, the polymerization can be performed without the piezoelectric nanoparticles and exogenous reducing agent. Contamination by nonliving chains formed from sonochemically generated radicals is avoided as well. All of these results supported that Cu(II)-based catalyst activation enabled by ultrasonication has a promising potential in scale-up of CRP.     

Linear polyethyleneimine supports for resins with retention properties for heavy metals. Part 2

Summary A linear polyethyleneimine obtained by cationic polymerization of 2-methyl-2-oxazoline was crosslinked with 1,4-dibromo-2-butene (IML-1). This resin subsequently was N-alkylated with dimethyl sulphate (IML-1M). With both resins were carried out analytical assays, such as: pH dependence for copper (II), uranium (VI), iron (II) and (III); maximum capacity of load for copper and uranium; elution assays. Moreover, the morphology by scanning electron microscopy and thermal stability were studied.