Copolymerization Of Ethylene Research Articles

Synthesis of Photoresponsive Fast Self‐healing Polyolefin Composites by Nickel‐Catalyzed Copolymerization of Ethylene and Lignin Cluster Monomers

AbstractPolymers may suffer from sudden mechanical damages during long‐term use under various harsh operating environments. Rapid and real‐time self‐healing will extend their service life, which is particularly attractive in the context of circular economy. In this work, a lignin cluster polymerization strategy (LCPS) was designed to prepare a series of lignin functionalized polyolefin composites with excellent mechanical properties through nickel catalyzed copolymerization of ethylene and lignin cluster monomers. These composites can achieve rapid self‐healing within 30 seconds under a variety of extreme usage environments (underwater, seawater, extremely low temperatures as low as −60 °C, organic solvents, acid/alkali solvents, etc.), which is of great significance for real‐time self‐healing of sudden mechanical damage. More importantly, the dynamic cross‐linking network within these composites enable great re‐processability and amazing sealing performances.

Improving assay feasibility and biocompatibility of 3D cyclic olefin copolymer microwells by superhydrophilic modification via ultrasonic spray deposition of polyvinyl alcohol

Sample partitioning is a crucial step towards digitization of biological assays on polymer microfluidic platforms. However, effective liquid filling into microwells and long-term hydrophilicity remain a challenge in polymeric microfluidic devices, impeding the applicability in diagnostic and cell culture studies. To overcome this, a method to produce permanent superhydrophilic 3-dimensional microwells using cyclic olefin copolymer (COC) microfluidic chips is presented. The COC substrate is oxidized using UV treatment followed by ultrasonic spray coating of polyvinyl alcohol solution, offering uniform and long-term coating of high-aspect ratio microfeatures. The coated COC surfaces are UV-cured before bonding with a hydrophobic pressure-sensitive adhesive to drive selective filling into the wells. The surface hydrophilicity achieved using this method remains unchanged (water contact angle of 9°) for up to 6 months and the modified surface is characterized for physical (contact angle & surface energy, morphology, integrity of microfeatures and roughness), chemical composition (FTIR, Raman spectroscopy) and coating stability (pH, temperature, time). To establish the feasibility of the modified surface in biological applications, PVA-coated COC microfluidic chips are tested for DNA sensing (digital LAMP detection of CMV), and biocompatibility through protein adsorption and cell culture studies (cell adhesion, viability, and metabolic activity). Kidney and breast cells remained viable for the duration of testing (7 days) on this modified surface, and the coating did not affect the protein content, morphology or quality of the cultured cells. The ultrasonic spray coated system, coating with 0.25 % PVA for 15 cycles with 0.12 A current after UV oxidation, increased the surface energy of the COC (naturally hydrophobic) from 22.04 to 112.89 mJ/m2 and improved the filling efficiency from 40 % (native untreated COC) to 94 % in the microwells without interfering with the biocompatibility of the surface, proving to be an efficient, high-throughput and scalable method of microfluidic surface treatment for diagnostic and cell growth applications.

Enhancing optical biosensing: Comparing two physical treatments for GPTES chemical functionalization of Cyclo-Olefin Copolymer foil

Cyclo-olefin-copolymer (COC) transparent films are currently the best choice for micro-fluidic bio-sensors for point-of-care diagnostic applications using optical signal detection. However, while the optical and mechanical properties of this polymer are extremely good, the adhesion of the bio-probes on this surface is not optimal, due to its chemical structure, that presents only saturated carbon bonds. The deposition of organo-silane molecules on the COC surface is one of the most effective ways to overcome this problem. But, for the surface functionalization, a surface physical treatment is necessary before the chemical modification of the COC surface. In this paper a comparison of the effectiveness of two different physical treatments, oxygen plasma and UV-ozone, is reported. In particular, the exposure time of the UV-Ozone treatment has been selected to avoid the problem of auto-fluorescence of the modified COC surface, that was observed also for relatively short UV exposure (around 10 min). An investigation of the reactive radicals created on the surface after the physical treatments and the following chemical modification with the organo-silane molecule (GPTES) has been performed using X-ray photoemission spectroscopy. The surface energy and morphology of the films have been also measured by contact angle and optical profilometry. Finally, the bio-probes adhesion performances of the COC surfaces obtained with the two physical treatments and the chemical modification were tested in a fluorescence-based assay, using an organic light emission diode to excite the fluorescence. We observed that the UV-ozone treatment allows to obtain a siloxane network with some reactive epoxy radicals on the COC surface, however, their quantity and distribution are less important and homogeneous than in the oxygen plasma treated surfaces.

Aqueous Keto-Polyethylene Dispersions from Catalytic Copolymerization of Ethylene and Carbon Monoxide in Water.

Water-soluble [P,O]Ni(II) catalysts enable the direct catalytic nonalternating copolymerization of fundamental comonomers ethylene and carbon monoxide (CO) in water as an environmentally friendly reaction medium. This yields stable aqueous dispersions of high molecular weight polyethylene containing ∼1 mol % of largely isolated in-chain keto groups in the form of particles with sizes between 100 nm and 1 μm. The intermediate species of chain growth resulting from incorporation of polar comonomers are amenable to specific chain termination pathways in conjunction with water.

Laser-Sintering of Cyclic Olefine Copolymer for Low Dielectric Loss Applications.

With increasing demands for data transfer, the production of components with low dielectric loss is crucial for the development of advanced antennas, which are needed to meet the requirements of next-generation communication technologies. This study investigates the impact of a variation in energy density on the part properties of a low-loss cyclic olefin copolymer (COC) in the SLS process as a way to manufacture complex low-dielectric-loss structures. Through a systematic variation in the laser energy, its impact on the part density, geometric accuracy, surface quality, and dielectric properties of the fabricated parts is assessed. This study demonstrates notable improvements in material handling and the quality of the manufactured parts while also identifying areas for further enhancement, particularly in mitigating thermo-oxidative aging. This research not only underscores the potential of COC in the realm of additive manufacturing but also sets the stage for future studies aimed at optimizing process parameters and enhancing material formulations to overcome current limitations.

Homogeneous Heat Transfer During Freeze-Drying Using Cyclic Olefin Polymer Vials

In pharmaceutical freeze-drying processes, batch homogeneity is an important quality attribute. In this context, the edge-vial-effect is a challenging phenomenon. Shortly, this effect describes that vials at the edges of the shelf dry faster and at a higher temperature compared to vials in the middle of the shelf. Studies by Ehlers et al. revealed that this effect mainly origins from the number of neighbor vials cooling each other, which is reduced for vials in corners and edges compared to vials in the middle. Due to the reduced heat transfer in cyclic olefin polymer (COP) vials, the adverse edge-vial-effect should be greatly reduced allowing a better batch uniformity. In this focused study, glass and COP vials are compared regarding this effect on a fully loaded shelf. A reference experiment with vials placed at distance using a specially designed frame is presented as well.

Ultra-high-molecular weight cyclic olefin copolymers with excellent all-round performance prepared via highly effective quasi-living copolymerization

Cyclic olefin copolymers (COCs) are a type of engineering thermoplastics that have excellent transparency, high heat deflection temperature, high tensile modulus, and rigidity, but low elongation (usually below 5 %). Achieving COCs with better mechanical performance, particularly toughness, while maintaining their other properties, is a critical goal that remains a significant challenge. Herein, COCs with an ultra-high-molecular weight (UHMW)—an average molecular weight of up to 2046 kDa—and a relatively narrow molecular weight distribution (Mw/Mn < 1.66), were prepared via a highly efficient, quasi-living catalytic system under mild polymerization conditions. The dependence of the tensile properties, impact properties, wear rate, mean friction coefficient, water vapor transmission rate, and oxygen permeability of the newly obtained COCs on their molecular weight was studied in-depth and compared with those of a commercial COC (Topas 6013, with a molecular weight of 144 kDa). As clearly shown, the obtained UHMW-COCs not only provided satisfactory heat resistance and excellent optical transparency but also demonstrated excellent mechanical performance, tribology behaviors, and barrier properties. Compared with the COCs with lower molecular weight but similar norbornene (NBE) incorporation and optical transmittance, these UHMW-COC samples possessed a higher glass transition temperature, higher tensile strength (up to 73.5 MPa), better elongation at break (6.8 %), better impact strength (4.0 kJ/m2), and a lower wear rate (2 × 10−5 mm3/mN), as well as a lower mean friction coefficient (0.48), lower water vapor transmission rate (0.68 g·mm·m−2·day−1), and lower oxygen permeability (1.60 Barrer). These all-round properties, together with their original advantages, make the UHMW-COCs promising for a broad range of high-end applications.

Effects of gamma radiation on cyclic olefin copolymers with varied norbornene content: Impacts on structure and properties at sterilization doses

Cyclic olefin copolymer (COC) is a transparent amorphous plastic known for its chemically inertness, biocompatibility, low density, and easy processability. These qualities have led to its widespread adoption in various cutting-edge applications, including the medical, packaging, optical and microelectronics. Radiation sterilization, utilizing high-energy irradiation, is a method for achieving highly effective sterilization of medical products. However, this process can induce changes in the color and properties of the COC materials. In order to comprehend the effects of ionizing radiation on COC, it is crucial to investigate the underlying reaction mechanisms. In this work, the effects of γ-ray irradiation on COC with different norbornene contents were examined. The finding revealed that tertiary alkyl radical content and the degree of oxidative degradation increased with an increase in norbornene content. Furthermore, the macroscopic properties experienced notable shifts, including decreased thermal stability, lower glass transition temperature and the change in color from colorless and transparent to yellow-green. Analysis of the melt index indicated a dominance of cross-linking phenomena with increased absorbed dose for COC with a norbornene content of 35%, while the melt flow rate steadily accelerated with the increase of absorbed dose for COC with norbornene content of 46%, 52% and 57%, leading to a predominant cracking behavior. The variation in tensile properties of the four COCs before and after irradiation were minimal, not exceeding 3%. Overall, this investigation sheds light on the intricate effects of ionizing radiation on COC and highlights the importance of understanding these mechanisms for practical applications.

Recent Advances in Nickel Catalysts with Industrial Exploitability for Copolymerization of Ethylene with Polar Monomers.

The direct copolymerization of ethylene with polar monomers to produce functional polyolefins continues to be highly appealing due to its simple operation process and controllable product microstructure. Low-cost nickel catalysts have been extensively utilized in academia for the synthesis of polar polyethylenes. However, the development of high-temperature copolymerization catalysts suitable for industrial production conditions remains a significant challenge. Classified by the resultant copolymers, this review provides a comprehensive summary of the research progress in nickel complex catalyzed ethylene-polar monomer copolymerization at elevated temperatures in the past five years. The polymerization results of ethylene-methyl acrylate copolymers, ethylene-tert-butyl acrylate copolymers, ethylene-other fundamental polar monomer copolymers, and ethylene-special polar monomer copolymers are thoroughly summarized. The involved nickel catalysts include the phosphine-phenolate type, bisphosphine-monoxide type, phosphine-carbonyl type, phosphine-benzenamine type, and the phosphine-enolate type. The effective modulation of catalytic activity, molecular weight, molecular weight distribution, melting point, and polar monomer incorporation ratio by these catalysts is concluded and discussed. It reveals that the optimization of the catalyst system is mainly achieved through the methods of catalyst structure rational design, extra additive introduction, and single-site catalyst heterogenization. As a result, some outstanding catalysts are capable of producing polar polyethylenes that closely resemble commercial products. To achieve industrialization, it is essential to further emphasize the fundamental science of high-temperature copolymerization systems and the application performance of resultant polar polyethylenes.

High-Refractive-Index Cross-Linked Cyclic Olefin Polymers with Excellent Transparency via Thiol-Ene Click Reaction.

High-refractive-index polymers are important optical materials in optoelectronics. Conventional cyclic olefin polymers (COPs), possessing many excellent optical properties, are a class of highly promising optical materials; however, one of the greatest obstacles is their low refractive index of n = 1.52-1.54. Here, one efficient strategy of first incorporating high molar refraction groups, including carbazolyl and indolyl moieties, into unsaturated COPs via ring-opening metathesis polymerization (ROMP) and then introducing another high molar refraction sulfur atom by a subsequent thiol-ene click reaction is presented. The obtained cross-linked COPs bearing both an aromatic group and sulfur possess significantly higher refractive indices (n = 1.611-1.684 at 589 nm) and highly optical transparency (approximately 95%) in the range of vis-NIR. This provides a way toward potential applications of new-generation optical materials.

Molecular dynamics study of free volume coalescence around nonyl ethoxylate in polyethylene with vinyl acetate‐modified branches

AbstractPolyethylene (PE) is susceptible to environmental stress cracking (ESC). In the presence of an amphiphilic compound and subjected to stress, ESC starts with cavitation followed by slow crack growth and ends with brittle fracture. In this study, we used molecular dynamics simulation to study how branch ends which were chemically modified with vinyl acetate groups affect free volume coalescence around an amphiphilic compound, nonyl ethoxylate (NE), dispersed in branched PE models. Branch ends modified with vinyl acetate significantly impact the free volume coalescence dynamics around NE. Compared with methyl branch ends, vinyl acetate branch ends show a much higher affinity, as quantified by the corresponding radial distribution functions, for the hydrophilic ethylene oxide‐segment of NE. However, this is not the case for the hydrophobic ethylene‐segment. Interestingly, vinyl acetate branch ends tend to reduce the power (amplitude) of the free volume size fluctuations around both the ethylene oxide‐ and ethylene‐segments. Indeed, the powers of the fluctuations with different PE branching characteristics decrease with increasing vinyl acetate concentration. We believe that free volume coalescence leads to cavitation and that vinyl acetate branches could inhibit cavitation, thereby crack propagation in PE. The power results seem to be consistent with the experimental observation that the addition of copolymer ethylene vinyl acetate to low‐density polyethylene improves the ESC resistance of the blend.Highlights Vinyl acetate branches reduce free volume coalescence activities. Vinyl acetate branches are attracted to the hydrophilic segment of NE. Cavitation likely starts from the free volume coalescence around NE.

Patterning of COC Polymers by Middle‐Energy Ion Beams for Selective Cell Adhesion in Microfluidic Devices

AbstractMicrofluidic devices play a crucial role in advanced cell biology applications, including cell separations, cultivations, migration and interaction studies, diagnostic devices, and organ‐on‐chips. One of the frequent purposes of such devices is the ability to selectively address the attachment of cells at defined locations on the surface. This study explores the application of middle‐energy carbon, oxygen, and nitrogen ions to locally modify the surface of cyclic olefin copolymer (COC) thermoplastic material, allowing selective cell growth on patterned polymer surfaces. The investigation considers ion element type, ion beam energy, and ion irradiation fluence, analyzing their influence on the modification effect. Characterization of the modified surfaces involves various surface‐analytical methods such as contact angle, energy dispersive spectroscopy (SEM‐EDX), atomic force microscopy (AFM), x‐ray photoelectron spectroscopy (XPS), rutherford backscattering spectrometry (RBS), and elastic recoil detection analysis (ERDA). The study extends to practical aspects, with a representative cancer cell line, MCF‐7, grown on the patterned surface to evaluate the degree of selective attachment. Additionally, the stability of the irradiated patterns is tested under elevated temperatures beyond the glass transition temperature (Tg), demonstrating the compatibility of the approach with hot embossing technology. The findings underscore the potential of ion beam treatment for COC in cell‐biology‐related applications, offering insights into surface modification techniques for enhanced functionality in microfluidic devices.

The third compound promoted ethylene homopolymerization and copolymerization with 1-octene by using metallocene catalyst

The third compound promoted ethylene homopolymerization and copolymerization with 1-octene by using metallocene catalyst

The Third Compound Promoted Copolymerization of Ethylene with 4‐Penten‐1‐ol by Using Metallocene Catalyst

AbstractOlefin coordination copolymerization with polar monomers is an important topic both in academia and industry. During copolymerization, polar monomers will seriously reduce the polymerization activity and the molecular weight of the copolymer, making it difficult to balance the two and the polar monomer incorporation at the same time. In this study, a metallocene catalyst, Ph2C(Cp)(Flu)ZrCl2, is used for the copolymerization of ethylene with 4‐penten‐1‐ol. The incorporation of 4‐penten‐1‐ol can be effectively increased by the introduction of the steric phenol as the third component (TC). Depending on the cocatalyst, the activity or molecular weight can be improved. It is believed that the promotion effect may work by the interaction of the steric phenol with the catalyst or cocatalyst. It is also suggested that in this system, polymerization is terminated by deactivation‐chain transfer mechanism rather than β‐X elimination due to back‐biting.

Cyclic olefin copolymer (COC) as a promising biomaterial for affecting bacterial colonization: investigation on Vibrio campbellii

Cyclic olefin copolymer (COC) has emerged as an interesting biocompatible material for Organ-on-a-Chip (OoC) devices monitoring growth, viability, and metabolism of cells. Despite ISO 10993 approval, systematic investigation of bacteria grown onto COC is a still not documented issue.This study discusses biofilm formations of the canonical wild type BB120 Vibrio campbellii strain on a native COC substrate and addresses the impact of the physico-chemical properties of COC compared to conventional hydroxyapatite (HA) and poly(dimethylsiloxane) (PDMS) surfaces.An interdisciplinary approach combining bacterial colony counting, light microscopy imaging and advanced digital image processing remarks interesting results. First, COC can reduce biomass adhesion with respect to common biopolymers, that is suitable for tuning biofilm formations in the biological and medical areas. Second, remarkably different biofilm morphology (dendritic complex patterns only in the case of COC) was observed among the examined substrates. Third, the observed biofilm morphogenesis was related to the interaction of COC with the conditioning layer of the planktonic biological medium. Fourth, Level Co-occurrence Matrix (CGLM)-based analysis enabled quantitative assessment of the biomass textural fractal development under different coverage conditions. All of this is of key practical relevance in searching innovative biocompatible materials for pharmaceutical, implantable and medical products.

Modified Bitumen Materials from Kazakhstani Oilfield

The oil bitumen BND 90/130, produced at the “LLP SP Caspi Bitum” with the modifier, which consists of copolymer of ethylene with butyl acrylate and glycidyl methacrylate taken in an amount of 0.5–1.6 wt%, and the tire reclaim (4–20 wt%), which is the destructate of mesh elastomers of different chemical nature, was modified; possibility of using the developed bitumen-elastomer binders in road asphalt concrete was justified. Modification of bitumen with a copolymer of ethylene with butyl acrylate and glycidyl methacrylate leads to an improvement in the properties of road bitumen: the softening point, hardness, deformability at low temperatures, elasticity, and adhesion to metal and mineral filler increase. It was shown that ethylene with butyl acrylate and glycidyl methacrylate chemically interacts with the functional groups of bitumen asphaltenes through the epoxy group of glycidyl methacrylate. Analysis of the spectra and group composition indicates an increased content of high molecular weight asphaltenes in the modified bitumen with a slight increase in structuring resins. It has been established that bitumen modified with rubber crumbs of 0.6–1.0 mm in size has high elasticity. The most effective composition of a bitumen-regenerated composite material based on tire reclaim has been determined. In terms of the totality of physicochemical and operational characteristics and comparative cost, the most acceptable is the bitumen-regenerated composition (with a regenerate content of 20%) and is superior in the complex of properties to bitumen modified with an optimal content of ethylene with butyl acrylate and glycidyl methacrylate (1.6%). The technology for modifying bitumen with tire reclaim is less time-consuming, more economically profitable, and environmentally effective, since it utilizes large-tonnage waste of worn-out tires. The resulting bitumen-polymer compositions have a high positive set of properties: softening point, hardness, elasticity, frost resistance, and low-temperature characteristics.

Monomer-Recyclable Polyester from CO2 and 1,3-Butadiene.

Synthesis of monomer-recyclable polyesters solely from CO2 and bulk olefins holds great potential in significantly reducing CO2 emissions and addressing the issue of plastic pollution. Due to the kinetic disadvantage of direct copolymerization of CO2 and bulk olefins compared to homopolymerization of bulk olefins, considerable research attention has been devoted to synthesis of polyester via the ring-opening polymerization (ROP) of a six-membered disubstituted lactone intermediate, 1,2-ethylidene-6-vinyl-tetrahydro-2H-pyran-2-one (𝜹-L), obtained from telomerization of CO2 and 1,3-butadiene. However, the conjugate olefin on the six-membered ring of 𝜹-L leads to serious Michael addition side reactions. Thus, the selective ROP of 𝜹-L, which can precisely control the repeating unit for the production of polyesters potentially amenable to efficient monomer recycling, remains an unresolved challenge. Herein, the first example of selective ROP of 𝜹-L is reported using a combination of organobase and N,N'-Bis[3,5-bis(trifluoromethyl)phenyl]urea as the catalytic system. Systematic modifications of the substituent of the urea show that the presence of electron-deficient 3,5-bis(trifluoromethyl)-phenyl groups is the key to the extraordinary selectivity of ring opening over Michael addition. Efficient monomer recovery of oligo(𝜹-L) is also achieved under mild catalytic conditions.

Noncovalent Ni–Phenyl Interactions Promoted α-Diimine Nickel-Catalyzed Copolymerization of Ethylene and Methyl Acrylate

Noncovalent Ni–Phenyl Interactions Promoted α-Diimine Nickel-Catalyzed Copolymerization of Ethylene and Methyl Acrylate

Promotion of chain growth and suppression of chain transfer by 2-methoxy group in diarylmethyl moiety in pyridine-imine nickel- and palladium-catalyzed ethylene (co)polymerization

Diarylmethyl substituents are commonly used to prevent chain transfer in late-transition metal-catalyzed ethylene polymerization. However, this substituent is not effective in inhibiting chain transfer in the pyridine-imine system. In this study, we introduced substituents at the 2-position of the diarylmethyl moiety to synthesize high molecular weight polyethylene in the pyridine-imine system. Using this strategy, we synthesized two pyridine-imine ligands with either ethyl or methoxy at the 2-position diarylmethyl moiety, along with their corresponding nickel and palladium complexes. These complexes were then utilized for ethylene (co)polymerization. The catalysts with OMe exhibited significantly higher polymerization activity (an order of magnitude, 105 vs. 104 g/(mol Ni·h)) compared to the corresponding Et catalysts. In addition, it was found that polyethylene produced from nickel and palladium catalysts with OMe has higher molecular weights than that produced from ethyl nickel and palladium catalysts. The nickel system produces polyethylene with a molecular weight up to an order of magnitude higher (an order of magnitude, 13.0–13.6 vs. 3.1–4.0 kg/mol). Similar results were also observed in the palladium-catalyzed copolymerization of ethylene with MA. Notably, the palladium catalyst with OMe has a significantly higher capacity for MA insertion (three times, 1.68–4.74 vs. 5.00–11.73 mol%) than the ethyl palladium catalyst, despite their similar spatial steric structures. The observed phenomenon may be attributed to the weak interaction between OMe and the metal center. In addition, 13C NMR analysis showed that the palladium-catalyzed polyethylene and E-MA copolymers are hyperbranched polymers, with the polar groups located at the ends of the branches.

Dynamics and Internal Structure Evolution during the Glass Transition of the Ethylene-Cyclic Olefin Copolymers: A Molecular Dynamics Simulation.

Amorphous ethylene-cyclic olefin copolymers (COCs) which can be used in cell phone lenses and prefilled syringes have attracted increasing attention due to their excellent and tunable thermal properties. In order to better explain the influence of COC microstructure (cyclic olefin types and content) on the glass transition mechanism, we used molecular dynamics (MD) simulations to track the evolution of free volume, diffusion coefficients, atomic mobility, trans conformation probabilities, and characteristic parameters of α-relaxation kinetics during the quenching process. MD results show that for the classic COC E-co-NB (ethylene-norbornene copolymer), an increase in cyclic olefin content from 25 to 50 mol % reduces atomic mobility, limiting the molecular chain movement at higher temperatures and improving Tg. Compared to NB, the more rigid rings in tricyclopentadiene (TCPD) and exo-1,4,4a,9,9a,10-hexahydro-9,10(1',2')-bridged phenylidene-1,4-bridged methylideneanthracene (HBM) have the following effects: (1) reducing the thermal expansion coefficient and overall chain mobility; (2) enhancing the diffusion energy barrier; (3) promoting the formation of local ordered structures; (4) accelerating α-relaxation dynamics at high temperatures and improving the dynamic fragility m. These lead to an upward shift in the temperature region where chain movement is limited and thus improve Tg and high-temperature dimensional stability. In this simulation, the correlation equation between Tg, m, and the microstructural parameters of COCs is established, which is of great significance for the development of COCs with high performance.