Copolymerization Of Ethylene Research Articles

Modification of surface topographies to inhibit candida biofilm formation.

The rise of infections associated with indwelling medical devices is a growing concern, often complicated by biofilm formation leading to persistent infections. This study investigates a novel approach to prevent Candida albicans attachment on the surface by altering surface topography. The research focuses on two distinct surface topographies: symmetry (squares) and non-symmetry (lines), created through a direct laser photolithography process on a Cyclic olefin copolymer (COC) surface. The wettability of these patterned surfaces was then examined immediately after fabrication and plasma treatment to mimic the sterilization process of indwelling devices through UV plasma. The results reveal directional wettability in the line pattern and size-dependent wettability in both square and line patterns. Candida albicans were cultured on these surfaces to assess the efficacy of the topography in preventing biofilm formation. The study demonstrates that symmetry and non-symmetry pattern topography inhibit biofilm formation, providing a promising strategy for mitigating Candida-associated infections on medical devices. The research sheds light on the potential of surface modification techniques to enhance the biocompatibility of medical devices and reduce the risk of biofilm-related infections.

Compact THz Polarization Splitter with Large Bandwidth Based on Cascade Hexagonal Porous Two-Core PCF

ABSTRACT A novel cyclic olefin copolymer (COC)-based terahertz (THz) polarization beam splitter (PBS) employing photonic crystal fiber (PCF) with cascade hexagonal porous two-core structure is proposed. The porous two-core is achieved by replacing the original two large air holes with three layers of small air holes. The mode coupling characteristics between the even and odd modes in the x- and y-polarization directions for the proposed THz PBS are explored using the time-domain finite difference (FDTD) method. The influence of PBS structural parameters on its coupling length is investigated. Numerical analysis results indicate that the bandwidths of 227.8 GHz (ranging from 1.8970 to 2.1248 THz) and 147 GHz (ranging from 1.928 to 2.075 THz) are acquired for the x- and y-polarization fundamental modes, respectively. The highest extinction ratios (ERs) are 114.5 dB and 72.3 dB, and the minimum insertion losses (ILs) are 0.0142 dB and 0.0369 dB for the x- and y-polarization fundamental modes, respectively. Moreover, the length of the proposed PBS is merely 11.655 mm. The proposed PBS will find potential applications in polarization-diverse THz systems, including broadband line-of-sight communication, real-time security checks, and high-resolution imaging.

Exploring the Impact of 3D Printing Parameters on the THz Optical Characteristics of COC Material.

In terahertz (THz) optical systems, polymer-based manufacturing processes are employed to ensure product quality and the material performance necessary for proper system maintenance. Therefore, the precise manufacturing of system components, such as optical elements, is crucial for the optimal functioning of the systems. In this study, the authors investigated the impact of various 3D printing parameters using fused deposition modeling (FDM) on the optical properties of manufactured structures within the THz radiation range. The measurements were conducted on 3D printed samples using highly transparent and biocompatible cyclic olefin copolymer (COC), which may find applications in THz passive optics for "in vivo" measurements. The results of this study indicate that certain printing parameters significantly affect the optical behavior of the fabricated structures. The improperly configured printing parameters result in the worsening of THz optical properties. This is proved through a significant change in the refractive index value and undesirable increase in the absorption coefficient value. Furthermore, such misconfigurations may lead to the occurrence of defects within the printed structures. Finally, the recommended printing parameters, which improve the optical performance of the manufactured structures are presented.

New insights into the catalyst and cocatalyst pre‐contact process in ethylene copolymerization

AbstractThe influence of pre‐contacting time and temperature as well as mixing intensity on polyethylene copolymerization has been investigated employing DSC, rotational rheometry tests, as well as particle size distribution analysis. For this purpose, a commercial‐supported Ziegler–Natta catalyst has been pre‐contacted with Teal as cocatalyst under different time, temperature, and stirring speed followed by similar polymerization process. It was found that the increase in mixing intensity has no impact on rheological properties; it causes increase in crystallinity percentage of polymer due to better distribution of active centers. Moreover, the pre‐contacting time represents the most impact on catalyst activity and rheology of polymer powder while the pre‐contacting temperature changes is mostly effective on controlling the morphology of polymer. Additionally, the results reveal that 10‐min pre‐contacting of catalyst and Teal under 10°C and stirring speed of 500 rpm was accompanied by highest catalyst activity and lowest content of fine particles.Highlights Pre‐activation was studied under different time and temperature. Adjusting pre‐contacting time influences the polymer morphology. Pre‐contacting under lower temperature results in narrower molecular weight distribution.

Study on the structure and property of metallocene ethylene/1-heptene and ethylene/1-octene copolymers

Polyolefin elastomers are typically copolymers of ethylene with 1-butene, 1-hexene, or 1-octene. Other types of comonomers have not been widely applied industrially. The cost of 1-heptene obtained from Fischer-Tropsch synthesis is only half that of 1-octene, making it a viable economical substitute. This work utilized 1-heptene from Fischer-Tropsch synthesis and 1-octene from ethylene oligomerization as research subjects. Eight metallocene POEs based on 1-heptene and 1-octene were synthesized using Me2Si(C5Me4)(N t Bu)]TiCl2 (Ti-CGC) catalyst. The copolymers’ molecular structures and physical properties were characterized using HT-GPC, Temperature Rising Elution Fractionation (TREF),13C-NMR, DSC, Melt Index (MI), and Tensile tests. Compared to 1-heptene, 1-octene more effectively reduces the melting point and crystallinity, while 1-heptene’s stronger comonomer insertion capability facilitates the production of copolymers with higher comonomer content. Similar ternary sequence distributions and molecular dynamics indicate that ethylene/1-heptene and ethylene/1-octene copolymers possess comparable chain microstructures. Both ethylene/1-heptene copolymers and ethylene/1-octene copolymers exhibit excellent toughness and mechanical properties. Although the activity and insertion capacity of ethylene and 1-heptene decrease at low comonomer concentrations, they significantly improve at higher comonomer concentrations. Thus, Fischer-Tropsch synthesis of metallocene ethylene/1-heptene copolymers can effectively reduce raw material costs and be a cost-effective alternative to ethylene/1-octene copolymers.

CGC-Scandium-Mediated Copolymerization of Ethylene with Amine-Functionalized Cyclic Olefins

CGC-Scandium-Mediated Copolymerization of Ethylene with Amine-Functionalized Cyclic Olefins

Development of Group IV Metal Complexes Bearing Thioether-Amido Ligands with Enhanced High-Temperature Catalytic Performance toward Olefin Copolymerization.

The development of homogeneous metal catalysts with both high activity and exceptional thermal stability is crucial for the efficient synthesis of polyolefin elastomers (POEs) through solution-phase olefin polymerization. In this study, a series of Hf (Hf1-Hf5), Zr (Zr1), and Ti (Ti1) complexes featuring thioether-amido ligands were synthesized and carefully characterized using advanced techniques such as 1H and 13C NMR spectroscopy as well as single-crystal X-ray diffraction analysis for Hf4 and Hf5. The results revealed that the catalytic activity and 1-octene incorporation efficiency of these metal complexes followed the trend Hf > Zr > Ti, underscoring the significant impact of the metal center on catalytic performance. Furthermore, the choice of ligands was found to play a critical role in dictating the catalytic properties, with ligands bearing less steric hindrance on the sulfur atom proving to be more favorable for copolymerization reactions. Notably, the Hf complex Hf1, featuring a methyl group on the sulfur atom, displayed exceptional catalytic activity as high as 21,060 kg(polymer)·mol-1(Hf)·h-1 toward ethylene/1-octene copolymerization at 120 °C and produced POE with a high molecular weight (Mw = 6.3 × 104 g·mol-1), relatively narrow distribution (Đ = 2.4), and high incorporation of 1-octene (34.1 mol %). This study demonstrates the potential of tailored ligand design in developing efficient metal catalysts for the production of high-value-added POEs.

B-037 Zeon original coating technology COP microplates for cell imaging

Abstract Background Zeon has developed high quality microplate made of Cyclo Olefin Polymer (COP) and special coat reagent for cell culture for Aurora microplates. The new 96 well-microplates have best-in-class properties for analysis of cultured cells can reduce the background of fluorescence images absolutely and excellent bottom flatness for observation of target. This enables to obtain high-precision data for cell analysis. Also, we developed Zeon original coating (ZOC) reagent specialized for COP surface. It is suitable for various cells including neurons derived from human induced pluripotent stem cells (iPSC), primary cells, general cell lines, and so on. ZOC coated COP microplates (ZOC plates) are fully-precoated and ready-to-use. Methods We evaluated the following points regarding ZOC plates. The cells used were derived from human iPSC. [1. Storage stability] ZOC plates were stored at room temperature for a long time. After that, cardiomyocyte cells were cultured for 3 days on the plates. The cell adhesion and beat rate were evaluated. [2. Neurite extension] Dopaminergic neurons were cultured for 14 days, then the neurite extension was evaluated. For comparison, a conventional poly-D-lysine* (PDL) coating was used. [3. Lot-to-lot variation] COP microplates coated with different lots of ZOC reagents were prepared. Glutamatergic neurons were cultured for 14 days on those plates, then the neurite extension and cell morphology were evaluated. *The typical coating reagent applied for neuronal culture. Results [1.] ZOC plates stored over 12 months at room temperature showed excellent cell adhesion, and the beat rate was equivalent to prepared just before use. [2.] ZOC plates tended to extend neurites more than PDL coated plates. [3.] No variation between lots was observed on ZOC plates regarding the neurite extension and cell morphology. Conclusions We suggest applying the combination of high accuracy for cell imaging using COP microplates and high performance for cell culture using ZOC can provide high precision data at bioassay research. This would be a significant value for development of drug screening processes at pharmaceutical company.

Bioactive modification of cyclic olefin copolymer (COC) film surfaces by hyaluronic acid and chitosan for enhanced cell adhesion

Cyclic olefin copolymer (COC) has recently emerged as an attractive material in biomedical fields for its high purity, excellent stability and chemical resistance, particularly in applications of microfluidic chips, prefilled syringes and bone regeneration. However, the high hydrophobicity of COC has inhibited the adhesion of cells and biological macromolecules, such as proteins, etc., significantly limiting its broader applications. In this study, we propose a new method to modify COC surfaces by sequential coating with polydopamine (PDA) followed by hyaluronic acid (HA) or O-carboxymethyl chitosan (CMC), while comparing the impacts of the positively charged HA and negatively charged CMC on protein adsorption and cell adhesion. FTIR and XPS measurements confirmed the successful modification on COC films, resulting in surfaces with highly increased hydrophilicity, anti-oxidative properties, and improved protein adsorption. Moreover, negatively charged HA, with signal transduction capabilities showed a greater effect in promoting cell adhesion. Thus, we present a straightforward strategy for enhancing the hydrophilicity of COC surfaces, offering new insights into COC modification and potential biomedical applications.

Development of Poly(lactic acid)-Based Biocomposites with Silver Nanoparticles and Investigation of Their Characteristics

Nowadays, the demand for food packaging that maintains the safety and quality of products has become one of the leading challenges. It can be solved by developing functional materials based on biodegradable polymers, such as poly(lactic acid) (PLA). In order to develop PLA-based functional materials with antibacterial activity, silver nanoparticles (AgNPs) were introduced. In the present study, AgNPs stabilized by a copolymer of ethylene and maleic acid were used. Under the joint action of shear deformations and high temperature, the biocomposites of PLA with poly(ethylene glycol) and AgNPs were produced. Their mechanical and thermal characteristics, water absorption, and structure were investigated using modern methods (DSC, FTIR, Raman spectroscopy, SEM). The effect of AgNP concentration on the characteristics of PLA-based biocomposites was detected. Based on the results of antibacterial activity tests (against Gram-positive and Gram-negative bacteria, along with yeast) it is assumed that these systems have potential as materials for extending the storage of food products. At the same time, PLA–PEG biocomposites with AgNPs possess biodegradability.

Installing a Trigger to Upcycle High-Density Polyethylene.

Creating C═C bonds as "weak" sites in the stable C-C chains of polyethylene (PE) is an appealing strategy to promote sustainable development of the polyolefin industry. Compared to methods, such as dehydrogenation and postpolymerization modification, the copolymerization of ethylene (E) and butadiene (BD) should be a convenient and direct approach to introduce C═C bonds in PE, whereas it encounters problems in controlling the composition and regularity of the copolymer due to the mismatched activities and mechanisms between the two monomers. Herein, we report by employing the amidinate gadolinium complex, controllable E/BD copolymerization was achieved, where BD was incorporated in the uniformly discrete 1,4 mode. The obtained copolymer possesses the same physical, mechanical, processing, and antioxygen (aging at 100 °C for 28 days) properties as commercial high-density-PE, which, strikingly, were degraded by C═C bonds into α,ω-telechelic oligomers with narrow distribution. These degraded functional products were transferred to compatibilizers via atom-transfer radical polymerization or immortal ring-opening polymerization, achieving upcycling.

Inhibiting the Appearance of Green Emission in Mixed Lead Halide Perovskite Nanocrystals for Pure Red Emission.

Mixed halide perovskites exhibit promising optoelectronic properties for next-generation light-emitting diodes due to their tunable emission wavelength that covers the entire visible light spectrum. However, these materials suffer from severe phase segregation under continuous illumination, making long-term stability for pure red emission a significant challenge. In this study, we present a comprehensive analysis of the role of halide oxidation in unbalanced ion migration (I/Br) within CsPbI2Br nanocrystals and thin films. We also introduce a new approach using cyclic olefin copolymer (COC) to encapsulate CsPbI2Br perovskite nanocrystals (PNCs), effectively suppressing ion migration by increasing the corresponding activation energy. Compared with that of unencapsulated samples, we observe a substantial reduction in phase separation under intense illumination in PNCs with a COC coating. Our findings show that COC enhances phase stability by passivating uncoordinated surface defects (Pb2+ and I-), increasing the formation energy of halide vacancies, improving the charge carrier lifetime, and reducing the nonradiative recombination density.

Aldehyde End‐Capped Degradable Polyethylenes From Hydrogen‐Controlled Ethylene/CO Copolymerization

AbstractTo access degradable polyolefin plastic, non‐alternating copolymerization of ethylene (E) and carbon monoxide (CO) for producing polyethylene (PE) with in‐chain ketones is particularly appealing; however, it still presents significant challenges such as molecular weight modulation (hydrogen response) and chain endgroup control (functional terminal). In this study, we achieved hydrogen‐controlled E/CO non‐alternating copolymerization using late transition metal catalysts. This process results in linear PEs containing the desired non‐alternating in‐chain keto groups (1.0–9.3 mol %) and with tunable molecular weights ranging from 43 to 195 kDa. In this reaction, H2 serves as a chain transfer agent, modulating the polymer's molecular weight, forming unique aldehyde endgroups and eliminating usual olefinic endgroups; CO undergoes non‐alternating insertion into the PE chain, resulting in a strictly non‐alternating structure (>99 %) for the keto‐PE. The dispersed incorporation of in‐chain keto groups retains bulk properties of PE and makes PE susceptible to photodegradation, which produces significantly lower molecular weight polymers and oligomers with unambiguous vinyl and acetyl terminals.

Aldehyde End-Capped Degradable Polyethylenes From Hydrogen-Controlled Ethylene/CO Copolymerization.

To access degradable polyolefin plastic, non-alternating copolymerization of ethylene (E) and carbon monoxide (CO) for producing polyethylene (PE) with in-chain ketones is particularly appealing; however, it still presents significant challenges such as molecular weight modulation (hydrogen response) and chain endgroup control (functional terminal). In this study, we achieved hydrogen-controlled E/CO non-alternating copolymerization using late transition metal catalysts. This process results in linear PEs containing the desired non-alternating in-chain keto groups (1.0-9.3 mol %) and with tunable molecular weights ranging from 43 to 195 kDa. In this reaction, H2 serves as a chain transfer agent, modulating the polymer's molecular weight, forming unique aldehyde endgroups and eliminating usual olefinic endgroups; CO undergoes non-alternating insertion into the PE chain, resulting in a strictly non-alternating structure (>99 %) for the keto-PE. The dispersed incorporation of in-chain keto groups retains bulk properties of PE and makes PE susceptible to photodegradation, which produces significantly lower molecular weight polymers and oligomers with unambiguous vinyl and acetyl terminals.

The flame retardant cyclic olefin copolymer composites with boric acid modified ZSM-5 synergists

The flame retardant cyclic olefin copolymer composites with boric acid modified ZSM-5 synergists

Improving Quantum Dot Stability Against Heat and Moisture with Cyclic Olefin Copolymer Matrix

Improving Quantum Dot Stability Against Heat and Moisture with Cyclic Olefin Copolymer Matrix

Zirconium and Hafnium Complexes Bearing Tridentate ONN-Ligands: Extremely High Activity toward Ethylene (Co)Polymerization.

The pursuit of high-performance catalysts in the realm of polyolefins is a constant goal. In this study, a range of zirconium (1-ZrCl3, 2-ZrCl3, 3-ZrCl4, 12-Zr) and hafnium (1-HfCl3, 12-Hf) complexes featuring phenoxy-imine-amine ONN-ligands (2,6-R2-C6H3-NH-C6H4-N═CH-C6H2-3,5-tBu2-OH; 1-L: R = H; 2-L: R = F; 3-L: R = iPr) were synthesized and characterized using NMR spectroscopy, as well as single-crystal X-ray diffraction for 2-ZrCl3, 3-ZrCl4, and 12-Zr. These Zr and Hf complexes exhibited remarkable efficiency for ethylene homopolymerization and copolymerization with 1-octene when paired with MAO as the cocatalyst. Notably, the Zr complexes outperformed the Hf complexes with the same ligand, underscoring the substantial impact of the metal center on catalytic performance. The substituents and coordination modes of the ligands also exerted significant influence on the catalytic behavior, affecting both the activity and properties of the resulting polymers. Particularly noteworthy was the exceptional activity of 1-ZrCl3, achieving activity as high as 6.30 × 108 g(PE)·mol-1(Zr)·h-1 for ethylene homopolymerization and generating bi- or multimodal distribution polyethylene. The activation of 1-ZrCl3 by 5 or 20 equiv of d-MAO afforded a dinuclear Zr complex bridged by two chlorides (μ-Cl2-(1-ZrCl2)2), which was analyzed and confirmed by in situ 1H NMR spectroscopy and single-crystal X-ray diffraction.

Copolymerization of ethylene and isoprene initiated by metallocene catalyst

In this study, we explore the dynamic nature of metallocene catalysts during ethylene/isoprene E/IP) copolymerization, with a focus on the influence of various reaction parameters. Challenges, why do olefinic catalysts show lower activity and molecular weight (Mw) at higher temperatures and low activity with higher diene content? Firstly, we investigate the observed phenomena of decreased catalyst activity and Mw at elevated temperatures using 1.25 μmole of the metallocene. Notably, a substantial increase in active sites from 30 °C to 40 °C, reaching a peak of 89 %. Surprisingly, further temperature increments lead to a noticeable decline in active sites. At 30 °C, the active site primarily engages in the insertion of IP through 3,4 connections, with no detectable cis-1,4 or trans-1,4 connections, which suggests a lack of stereoselectivity at this temperature. At 40–50°C, cis/trans-1,4 connections and active sites are approaching a higher level. This implies a reduction in chain transfer reactions, making catalytic active sites more favorable to cis/trans-1,4 connections. Secondly, we observe a remarkable impact of IP concentration in the E/IP copolymers, active centers, and activity show stability when the amount of IP was 0.116–0.48 mol/L and then started to decline when the amount of IP 0.96 mol/L, indicating a threshold beyond which deactivation occurs. Increasing IP concentration not only reduces activity and active sites but also fails to reactivate dormant polyethylene sites. The Mw and active centers of copolymers progressively decrease with elevated IP concentration, suggesting a faster chain transfer reaction with IP compared to E.

Direct synthesis of polar functionalized linear low density polyethylene (LLDPE) using slow-chain-walking palladium catalysts

Linear low-density polyethylene (LLDPE) is the most widely produced type of polyethylene resin. In this work, we detailed the synthesis and analysis of two bulky α-diimine Pd(II) complexes. These Pd(II) complexes can efficiently synthesize LLDPE-type polyethylene materials (ρ = 0.91–0.93 g/cm3) through ethylene slow-chain-walking polymerization. More interestingly, benefiting from the cationic bulky Pd(II) complexes, polar-functionalized LLDPEs (ρ = 0.91–0.92 g/cm3) are also produced by copolymerization of ethylene with various polar monomers such as 10-methyl undecanoate, methyl acrylate, 10-undecenoic acid. The copolymerization maintains the slow-chain-walking polymerization feature, resulting in a polar copolymer with a high melting point and low branching density. The results of 13C NMR spectral also reveal that polar groups are mainly located at the end of the branches in polar-functionalized LLDPEs.

Surface‐Reengineering of BNNs@Hydrocarbon Polymer Composites for Ultra‐Low Dielectric Constant for High‐Frequency Applications

AbstractThis research investigates the synthesis and evaluation of cyclic olefin copolymer (COC) composites with surface‐engineered boron nitride nanosheets (BNNs) at various concentrations. The study focuses on the impact of Cetyltrimethylammonium bromide (CTAB) on BNNs′ surface functionalization to improve their dispersion within the COC matrix, including its dielectric behavior, dielectric breakdown strength, thermal management capabilities, hygroscopic properties, and mechanical robustness. The methodological approach adopted for the fabrication of COC/BNNs hybrid composites commenced with the synthesis of BNNs, surface functionalization of BNNs, in‐situ mixing and hot‐press. This step aimed to enhance compatibility and adhesion between BNNs and the COC matrix, facilitating more homogeneous nanofiller dispersion. The investigative scope of this study encompassed a rigorous evaluation of the resultant composites, with a particular emphasis on their dielectric properties. The dielectric constant (ϵ′) and loss tangent (δ) were measured at a frequency of 10 GHz, revealing an ultra‐low dielectric constant of 1.28, an exceptionally minimal loss tangent of 0.000146, a remarkable 327% (In‐plane) & 129% (axial) increase of thermal conductivity, significant improvement of dielectric breakdown strength up to 88.4 mV/mm, and low water absorptions observed. These results indicate the potential of COC/BNNs composites for high‐frequency electronic packaging applications requiring low dielectric constants.