Monoxide Copolymers Research Articles

Controlled Radical Polymerization of Acrylates and Isocyanides Installs Degradable Functionality into Novel Copolymers.

Installing ketones into a polymer backbone is a known method for introducing photodegradability into polymers; however, most current methods are limited to ethylene-carbon monoxide copolymerization. Here we use isocyanides in place of carbon monoxide in a copolymerization strategy to access degradable nonalternating poly(ketones) that either maintain or enhance the thermal properties. A cobalt-mediated radical polymerization of acrylates and isocyanides synthesizes nonalternating poly(acrylate-co-isocyanide) copolymers with tunable incorporation using monomer feed ratios. The kinetic product of the polymerization is a dynamic β-imine ester that tautomerizes to the β-enamine ester. Hydrolysis of this copolymer affords a third copolymer microstructure─the elusive nonalternating poly(ketone)─from a single copolymerization strategy. Analysis of the copolymer properties demonstrates tunable thermal properties with the degree of incorporation. Finally, we show that poly(acrylate-co-isocyanide) and poly(acrylate-co-ketone) are photodegradable with 390 nm light, enabling chain cleavage.

Nickel-Catalyzed Selective Incorporation of Isolated In-Chain Carbonyls into Ethylene/Carbon Monoxide Copolymer Using Metal Carbonyls as a Carbonyl Source

Abstract Non-alternating copolymers of ethylene and carbon monoxide were obtained by nickel-catalyzed polymerization of ethylene in the presence of Fe2(CO)9 as a carbon monoxide source. Higher selectivity to isolated ketone group than the previously reported nickel-catalyzed systems, while having a higher catalytic activity than the palladium catalysts in our previous report has been achieved. Furthermore, various P-stereogenic phosphine-phenolate ligands were developed to investigate the effect of ligand structure on the copolymerization. Finally, the degradability of the resulting polymer was evaluated.

Mechanistic Insights into Ni(II)-Catalyzed Nonalternating Ethylene-Carbon Monoxide Copolymerization.

Polyethylene materials with in-chain-incorporated keto groups were recently enabled by nonalternating copolymerization of ethylene with carbon monoxide in the presence of Ni(II) phosphinephenolate catalysts. We elucidate the mechanism of this long-sought-for reaction by a combined theoretical DFT study of catalytically active species and the experimental study of polymer microstructures formed in pressure-reactor copolymerizations with different catalysts. The pathway leading to the desired nonalternating incorporation proceeds via the cis/trans isomerization of an alkyl-olefin intermediate as the rate-determining step. The formation of alternating motifs is determined by the barrier for the opening of the six-membered C,O-chelate by ethylene binding as the decisive step. An η2-coordination of a P-bound aromatic moiety axially oriented to the metal center is a crucial feature of these Ni(II) catalysts, which also modulates the competition between the two pathways. The conformational constraints imposed in a 2′,6′-dimethoxybiphenyl moiety overall result in a desirable combination of disfavoring ethylene coordination along the alternating incorporation pathway, which is primarily governed by electronics, while not overly penalizing the nonalternating chain growth, which is primarily governed by sterics.

Selective, Catalytic Oxidations of C–H Bonds in Polyethylenes Produce Functional Materials with Enhanced Adhesion

Summary The synthesis of functional and processable polyethylenes from simple vinyl monomers with controlled molecular weights and architectures has been a grand challenge of polymer chemistry. Post-polymerization modification of the homopolymers of ethylene is attractive for this purpose but has been hampered by the lack of efficient methods for the selective functionalization of C–H bonds in polyolefins. We report the selective, catalytic oxidation of C–H bonds in commodity polyethylenes with varying molecular weights and architectures. Remarkably, the functionalized materials, even at low levels of functionalization, exhibit physical properties that are absent in unmodified polyolefins, such as strong adhesion and the ability to be painted with common waterborne latex paint. Such observations indicate that selectively modified polyethylenes as described here may help to transform existing commodity plastics into more valuable and potentially more sustainable materials.

Photodegradable branched polyethylenes from carbon monoxide copolymerization under benign conditions

Small amounts of in-chain keto groups render polyethylene (PE) photodegradable, a desirable feature in view of environmental plastics pollution. Free-radical copolymerization of CO and ethylene is challenging due to the formation of stable acyl radicals which hinders further chain growth. Here, we report that copolymerization to polyethylenes with desirable low ketone content is enabled in dimethyl carbonate organic solvent or under aqueous conditions at comparatively moderate pressures <350 atm that compare favorable to typical ethylene polymerization at 2000 atm. Hereby, thermoplastic processable materials can be obtained as demonstrated by injection molding and tensile testing. Colloidally stable dipersions from aqueous polymerizations form continuous thin films upon drying at ambient conditions. Extensive spectroscopic investigation including 13C labeling provides an understanding of the branching microstructures associated with keto groups. Exposure of injection molded materials or thin films to simulated sunlight under sea-like conditions results in photodegradation.

Formal Aryne/Carbon Monoxide Copolymerization To Form Aromatic Polyketones/Polyketals

A palladium-catalyzed alternating copolymerization of [2.2.1]oxabicyclic alkenes 1 with carbon monoxide afforded isomer mixtures of polyketones 2ktn and polyketals 2ktl. Subsequent acid-induced dehydration of polymer 2 furnished novel aromatic polymers consisting of polyketones 3ktn and polyketals 3ktl units. This formal aryne/carbon monoxide copolymerization thus generated the first example of poly(aryne-alt-carbon monoxide)s, in which o-arylene and carbonyl units are incorporated in an alternating fashion.

Morphology control of ethylene/CO copolymer with a novel inverse suspension polymerization

To control the morphology of polymer particles produced by ethylene/carbon monoxide copolymerization, we have implemented a strategy involving the inverse suspension polymerization. The inverse suspension polymerization carried by using a palladium catalyst system (BDOMPP/Pd(AcO)2 with TFA) in aqueous methanol droplets dispersed in cyclohexane. The effects of the polymerization conditions and the composition of reaction mediums on the activity and morphology of polyketone (PK) particles were examined. The obtained PK afforded well-controlled particles with a high bulk density of 0.19g/cm3. The molecular weight of PK obtained by inverse suspension polymerization was almost identical to that observed in a conventional slurry-type process. Moreover, reactor fouling was dramatically suppressed by the application of this novel polymerization process.

Polyoximes based on the alternating carbon monoxide copolymers

A new efficient method for the synthesis of polyoximes was developed based on the oximation of the alternating carbon monoxide copolymer with ethylene or styrene in the polar aprotic solvent.

Ortho-Phosphinobenzenesulfonate: A Superb Ligand for Palladium-Catalyzed Coordination–Insertion Copolymerization of Polar Vinyl Monomers

Ligands, Lewis bases that coordinate to the metal center in a complex, can completely change the catalytic behavior of the metal center. In this Account, we summarize new reactions enabled by a single class of ligands, phosphine-sulfonates (ortho-phosphinobenzenesulfonates). Using their palladium complexes, we have developed four unusual reactions, and three of these have produced novel types of polymers. In one case, we have produced linear high-molecular weight polyethylene, a type of polymer that group 10 metal catalysts do not typically produce. Secondly, complexes using these ligands catalyzed the formation of linear poly(ethylene-co-polar vinyl monomers). Before the use of phosphine-sulfonate catalysts, researchers could only produce ethylene/polar monomer copolymers that have different branched structures rather than linear ones, depending on whether the polymers were produced by a radical polymerization or a group 10 metal catalyzed coordination polymerization. Thirdly, these phosphine-sulfonate catalysts produced nonalternating linear poly(ethylene-co-carbon monoxide). Radical polymerization gives ethylene-rich branched ethylene/CO copolymers copolymers. Prior to the use of phosphine-sulfonates, all of the metal catalyzed processes gave completely alternating ethylene/carbon monoxide copolymers. Finally, we produced poly(polar vinyl monomer-alt-carbon monoxide), a copolymerization of common polar monomers with carbon monoxide that had not been previously reported. Although researchers have often used symmetrical bidentate ligands such as diimines for the polymerization catalysis, phosphine-sulfonates are unsymmetrical, containing two nonequivalent donor units, a neutral phosphine, and an anionic sulfonate. We discuss the features that make this ligand unique. In order to understand all of the new reactions facilitated by this special ligand, we discuss both the steric effect of the bulky phosphines and electronic effects. We provide a unified interpretation of the unique reactivity by considering of the net charge and the enhanced back donation in the phosphine-sulfonate complexes.

Ethylene and Styrene Carbon Monoxide Copolymerization Catalyzed by Pyrazolyl Palladium(II) Complexes

The pyrazolyl pyridylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]pyridin-2-ylmethyleneimine (L1) and [2-(3,5-di-tert-butylpyrazol-1-yl)ethyl]pyridin-2-ylmethyleneimine (L2) and pyrazolyl thienylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]thiophen-2-ylmethyleneimine (L3), [2-(3,5-di-tert-butyl-pyrazol-1-yl)ethyl]thiophen-2-ylmethyleneimine (L4), [2-(3,5-dimethylpyrazol-1-yl)ethyl]-2-bromothiophen-2-ylmethyleneimine (L5), and [2-(3,5-di-tert-butyl-pyrazol-1-yl)ethyl]-2-bromothiophen-2-ylmethyleneimine (L6) were synthesized by condensation of the appropriate pyrazolylamine and the corresponding aldehyde. Reactions of L1–L6 with [PdCl(Me)(cod)] gave the corresponding palladium(II) complexes [PdCl(Me)(L)] (where L = L1 (1a), L2 (2a), L3 (3a), L4 (4a), L5 (5a), L6 (6a)) in very good yields. The pyridylimine ligands L1 and L2 were found to coordinate via the imine and pyridine nitrogen atoms, while the thienylimine ligands L3–L6 coordinate via imine and pyrazolyl nitrogen atoms to the palladium. The ca...

Influence of formic acid and water on the [Pd(OAc)2(dppp)] catalyzed ethene–carbon monoxide copolymerization carried out in aprotic organic solvents

The copolymerization of ethene with carbon monoxide catalyzed by [Pd(OAc)2(dppp)] in an aprotic solvent such as 1,4-dioxane or nitromethane is efficiently promoted both by H2O and HCOOH and yields a perfectly alternating polyketone (PK). The influence of the concentration of the promoters, pressure and temperature on the catalyst productivity and the limiting viscosity number (LVN) has been studied. The productivity increases with the increase of temperature and pressure. The LVN increases upon increasing the pressure and lowering the temperature. At 363K and 9.0MPa, in HCOOH/H2O/1-4,dioxane (2.7/1.35/1 molar ratio), the productivity is 37.50kgPK(gPdh)−1 (LVN 2.77dLg−1).LVN lowers upon increasing the concentration of the acid, suggesting that it is involved in the protonolysis chain-transfer process.

Molecular-topological and thermal properties of gamma-irradiated alternating carbon monoxide-ethylene copolymer

Gamma-irradiation to a dose of up to 2000 kGy does not lead to substantial changes in the topological structure of a carbon monoxide copolymer with ethylene, thereby suggesting it high radiation resistance. The topological structure of unirradiated and irradiated copolymer samples is polyblock in nature having four crystalline phases as the branching “junctions” in the pseudo-network structure of its amorphous block. Copolymer molecular flow begins after completion of melting of its high-melting fraction and at an onset flow temperature of 484 ± 4 K regardless of the absorbed radiation dose. The irradiated and unirradiated copolymer releases the same gaseous products upon heating, and the irradiation itself does not affect the onset temperature of effective gas evolution.

Morphology Control of Polymer Particles in Ethylene/Carbon Monoxide Copolymerization

Morphology Control of Polymer Particles in Ethylene/Carbon Monoxide Copolymerization

Morphology Control of Polymer Particles in Ethylene/Carbon Monoxide Copolymerization

Unter Druck gesetzt werden katalysatorhaltige, in Wasser dispergierte 1-Octanoltröpfchen, um so die Morphologie der Polymerpartikel bei der Ethylen/CO-Copolymerisation zu steuern. Der Pd-Katalysator sollte mit lipophilen, langen Alkylketten ausgestattet sein. Polymerpartikel mit einer Größe von 0.5–1.0 mm (siehe Aufnahmen) und Volumendichten von 0.2–0.3 g mL−1 werden ohne Reaktorverschmutzung produziert. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Comparative Study on the Degradation Behavior of Ethylene-carbon Monoxide Copolymers under Natural Environment in Japan and China

Comparative Study on the Degradation Behavior of Ethylene-carbon Monoxide Copolymers under Natural Environment in Japan and China

Microscale digital image correlation study of irradiation induced ductile-to-brittle transition in polyethylene

The transition from ductile-to-brittle (DTB) response in polymers can be triggered by many factors such as temperature, strain rate, and environmental effects. The focus of this paper is on investigating the DTB transition that occurs in a polyethylene carbon monoxide copolymer (ECO) under the influence of ultraviolet (UV) irradiation. As ECO is subjected to increased amounts of UV light it becomes stiffer and more brittle because of increased cross-linking and simultaneous chain scission. Consequently, its failure processes also change with UV irradiation transitioning from a shear yielding mechanism typical of ductile polymers to a crazing mechanism typical of brittle polymers. An in-house built microtensile tester placed under a microscope is used to image at the microscale (1–10 µm/pixel) the failure processes of ECO irradiated for 0, 10, and 50 h. The full-field optical method of digital image correlation is used to image the area around a crack tip in a microscale fracture sample. The results show a significant region of K-dominance very near the crack tip in both the shear yielding (10 h irradiation) and the crazing (50 h irradiation) samples. Crack extension curves are also obtained and are seen to be consistent with macroscopic data obtained elsewhere.

Effect of Wavelength of Irradiated Light on the Photodecomposition of Ethylene-carbon Monoxide Copolymers

Effect of Wavelength of Irradiated Light on the Photodecomposition of Ethylene-carbon Monoxide Copolymers

Electric impedance study of elastic alternating propylene–carbon monoxide copolymer (PCO-200)

The electrical properties of elastic alternating propylene–carbon monoxide copolymer (PCO-200) were investigated using the impedance spectroscopy technique. The results revealed a phase transition at about 70°C where the material transforms from its insulating phase of conductivity in the order of 6×10−9 to about 9×10−5 (Ωm)−1, The second phase is characterized by temperature dependent electrical relaxation phenomena. The plot of the complex electric modulus and the complex impedance yields semicircles in the temperature range 70 up to 110°C and a decreasing radius with increasing temperature. The activation energy was found to be in the order of 0.8eV.

Thermal oxidation and photo- and biodestruction of the statistical copolymer of ethylene with carbon monoxide

Thermal and photooxidation of the statistical copolymer of ethylene containing 1.5% carbonyl units -C(O)- by molecular O2 was studied at 160–200°C in the presence and absence of phenyl-β-naphthylamine (PNA) antioxidant. The incorporation of a small number of -C(O)- groups into the polyethylene chain insignificantly decreased the rate of thermal (dark) oxidation but substantially accelerated oxidation under the action of light. At the same time, the oxidation of the copolymer occurred at a lower rate than the oxidation of pure polyethylene (PE), which was evidence of an important role played by intramolecular oxidation chain propagation in PE, which is disturbed already at a comparatively low fraction of foreign units. Phenyl-β-naphthylamine noticeably decelerated oxidation. The rate of polymer biodestruction was much higher than the rate of PE biodestruction. The influence of biodestruction on the physicomechanical properties of samples was studied by ultrasonic microscopy. The velocity of sound propagation in PE was somewhat lower compared with the ethylene-carbon monoxide copolymer (ECO). Clearly, the introduction of a small amount of CO molecules into the polyethylene chain changed the microstructure of PE. The structure of ECO was more ordered and denser because of plasticization by metabolites.

Determination of Gurson–Tvergaard–Needleman Model Parameters for Failure of a Polymeric Material

In this work, the Gurson–Tvergaard–Needleman model, commonly used for metallic materials, is applied to the failure of a polymeric material – specifically a polyethylene carbon monoxide copolymer, which is an enhanced photodegradable material. Gurson–Tvergaard–Needleman model parameters for this material are obtained using the Nelder–Mead simplex method when correlating experimental and numerical results of both tensile and fracture specimens. Results show that the Gurson–Tvergaard–Needleman model can also be used for polymeric materials with selection of proper parameters that are quite different from the ones proposed for metallic materials.