Search results for " polymerization"

Polypropylene and poly(ethylene-co-1-octene) effective synthesis with diamine-bis(phenolate) complexes: Effect of complex structure on catalyst activ…

2017

A series of group 4 metal complexes bearing amine-bis(phenolate) ligands with the amino side-arm donor: (μ-O)[Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)2ZrCl]2 (1a), R2N(CH2)2N(CH2-2-O-3-R1-5-R2-C6H2)2TiCl2 (R = Me, R1, R2 = tBu (2a), R = iPr, R1, R2 = tBu (2b), R = iPr, R1 = tBu, R2 = OMe (2c)), and Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)(CH2-2-O-C6H4)TiCl2 (2d) are used in ethylene and propylene homopolymerization, and ethylene/1-octene copolymerization. All complexes, upon their activation with Al(iBu)3/Ph3CB(C6F5)4, exhibit reasonable catalytic activity for ethylene homo- and copolymerization giving linear polyethylene with high to ultra-high molecular weight (600·× 103–3600·× 103 g/mol). The activi…

Amino Functional Poly(ethylene glycol) Copolymers via Protected Amino Glycidol

2010

The synthesis of poly(ethylene glycol) (PEG) copolymers with multiple amino functionalities within the chain is described, relying on an epoxide comonomer bearing a protected amino group. N,N-dibenzyl amino glycidol (DBAG) and ethylene oxide (EO) were copolymerized via anionic polymerization, leading to well-defined polymers with varied comonomer content and low polydispersities (Mw/Mn in the range of 1.1 to 1.2). Subsequent hydrogenolysis with Pearlman’s catalyst afforded poly(ethylene glycol-co-amino glycerol)s (PEG-co-PAG) with a precisely adjusted number of randomly incorporated amino groups in the range of 2−15%. For the first time, the kinetics of an EO copolymerizations have has been…

Effective copolymerization of ethylene with α,ω-alkenols and homopolymerization of α,ω-alkenols catalyzed by aminophenolate zirconium complex

2019

Abstract A zirconium complex of diamine-bis(phenolate) ligand, [(tBu2O2NN’)ZrCl]2(μ-O) where (tBu2O2NN’) = Me2N(CH2)2N(CH2–2-O−-3,5-tBu2-C6H2)2, activated with (iBu)3Al/Ph3CB(C6F5)4, was for the first time used in copolymerization of ethylene with unsaturated alcohols (CH2 = CH(CH2)nCH2OH, where n = 7, 8, 3). The hydroxyl groups of comonomers were protected with R3-xAlClx (where x = 0 or 1, R = iBu, Et). In contrast to the formerly reported catalysts, the activity of this catalyst is much higher in ethylene/alkenols copolymerization than in ethylene homopolymerization and its lifetime is long. Moreover, the copolymers with high polar comonomer contents (up to 16.4 mol%, 52.3 wt%) were produ…

Organometallic vanadium‐based heterogeneous catalysts for ethylene polymerization. Study of the deactivation process

1998

Slurry polymerizations of ethylene over vanadium catalysts (based on VCl4 and VOCl3) and their MgCl2(THF)2-supported equivalents were studied. Unsupported vanadium catalysts were found to be unstable while the vanadium active sites deposited on the MgCl2(THF)2 complex are stable. A sharply outlined correlation was found between the concentration of vanadium(III) and catalyst productivity. The high activity and stability of the vanadium catalyst when supported on the magnesium complex is attributed to the increase of resistance to reduction of active vanadium(III) to inactive vanadium(II) by an organoaluminium co-catalyst.

Dichlorovanadium(IV) diamine-bis(phenolate) complexes for ethylene (co)polymerization and 1-olefin isospecific polymerization

2018

Abstract Two vanadium complexes bearing amine-bis(phenolate) ligands with the amino side-arm donor, [V{Me2NCH2CH2N(CH2-2-O-3,5-tBu2-C6H2)2}Cl2] (1) and [V{Me2NCH2CH2N(CH2-2-O-3,5-tBu2-C6H2)(CH2-2-O-C6H4)}Cl2] (2), were synthesised and characterized by FTIR and 1H NMR spectroscopy. Upon activation with Al(iBu)3/Ph3CB(C6F5)4, these complexes became active catalysts for 1-octene polymerization giving highly stereoregular polymers (mmmm ∼ 90%) having regioirregularly arranged units. The catalytic activity of the catalysts in ethylene homo- and copolymerization, and their ability to incorporate a comonomer were highly dependent on both the activator type and the complex structure. 1/EtAlCl2 exhi…

Microflow Technology in Polymer Synthesis

2012

Microflow technology, i.e., the use of microfluidic devices for continuous flow synthesis, represents a highly useful and increasingly popular method in organic chemistry. Recently, also an increasing number of polymer synthesis protocols attain benefit from this technique. In particular, the control of highly exothermic, fast polymerization reactions can be improved due to the excellent heat and mass transfer within the small dimensions of the microreactors. Continuous flow setups with different micromixer geometries and flow patterns are currently used for the preparation of a variety of macromolecular architectures by ionic and (controlled) radical polymerization techniques. This Perspec…

Counter anion binding in the phenoxyimine, salan and metallocene olefin polymerization catalysts activated with perfluorophenylborate

2012

Abstract Ion pair separation is a process that may influence the activity of homogeneous catalysts of olefin polymerization. We have studied the energy of separation for selected titanium and zirconium metallocene and post-metallocene catalytic ion pairs by means of DFT, dispersion-corrected DFT and Paired Interacting Orbitals method (PIO). Unusually weak cation–anion interactions in the bis(phenoxyimine) systems were attributed to strong electron-donating properties of the phenoxyimine ligands. Energy decomposition analysis (EDA) revealed that almost 70% of the counter ion binding energy results from electrostatic interactions. The PIO method made it possible to analyze the nature of the c…

2016

The structure–property relationship study of a series of cationic Ir(III) complexes in the form of [Ir(C^N)2(dtBubpy)]PF6 [where dtBubpy = 4,4′-di-tert-butyl-2,2′-bipyridine and C^N = cyclometallating ligand bearing an electron-withdrawing group (EWG) at C4 of the phenyl substituent, i.e., −CF3 (1), −OCF3 (2), −SCF3 (3), −SO2CF3 (4)] has been investigated. The physical and optoelectronic properties of the four complexes were comprehensively characterized, including by X-ray diffraction analysis. All the complexes exhibit quasireversible dtBubpy-based reductions from −1.29 to −1.34 V (vs SCE). The oxidation processes are likewise quasireversible (metal + C^N ligand) and are between 1.54 and …

Self-cleaning antimicrobial surfaces by bio-enabled growth of SnO2 coatings on glass.

2013

Conventional vapor-deposition techniques for coatings require sophisticated equipment and/or high-temperature resistant substrates. Therefore bio-inspired techniques for the fabrication of inorganic coatings have been developed in recent years. Inspired by the biology behind the formation of the intricate skeletons of diatoms orchestrated by a class of cationic polyamines (silaffins) we have used surface-bound spermine, a naturally occurring polyamine, to promote the fast deposition of homogeneous, thin and transparent biomimetic SnO2 coatings on glass surfaces. The bio-enabled SnO2 film is highly photoactive, i.e. it generates superoxide radicals (O2˙(-)) upon sunlight exposure resulting i…

Incorporation of a tricationic subphthalocyanine in an organic photovoltaic device

2013

A new tricationic subphthalocyanine was synthesized and employed as light-harvesting and donor material in an ionic solid state organic photovoltaic cell. The incorporation of ionic dyes in organic photovoltaics aims to take advantage of ionic movement in order to enhance the charge transport properties of these materials. In this preliminary study, we report the results obtained in the fabrication of a partially solution-processed device with a cationic dye, where an effiency of 0.5% was reached.