Hydroxypropyl Research Articles

Understanding Separation of Oil-Water Emulsions by High Surface Area Polymer Gels Using Experimental and Simulation Techniques.

This work examines the functional dependence of the efficiency of separation of oil-water emulsions on surfactant adsorption abilities of high surface area polymer gels. The work also develops an understanding of the factors and steps that are involved in emulsion separation processes using polymer gels. The work considers four polymer gels offering different surface energy values, namely, syndiotactic polystyrene (sPS), polyimide (PI), polyurea (PUA), and silica. The data reveal that surfactant adsorption abilities directly control the emulsion separation performance. The gels of sPS and PI destabilize the emulsions due to significant surfactant adsorption. The surfactant-lean oil droplets are then absorbed in the pores of sPS and PI gels due to the preferential wettability of the oil phase. The PUA and silica gels are more hydrophilic and show a lower surfactant adsorption ability. These gels cannot effectively remove the surfactant molecules from the emulsions, leading to a poor emulsion separation performance. The study uses simulation data to understand the adsorption characteristics of two poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer surfactants. The simulation results are used for the interpretation of emulsion separation performance by the gels.

Deciphering the Influence of Zwitterionic Surfactants on Pluronic Co-assemblies: A Synergistic Odyssey through Spectroscopic, Microscopic, and Scattering Techniques.

Fundamental investigations into the photophysical properties and microenvironmental features of pluronic-zwitterionic surfactant mixed assemblies are essential for advancing our understanding of molecular interactions at the nanoscale, setting the stage for innovative solutions in drug delivery, diagnostics, and other applications of pluronic-zwitterionic surfactant assemblies. This investigation explores the intricate photophysics of pluronic-zwitterionic surfactant mixed assemblies, utilizing the twisted intramolecular charge transfer state forming styryl dye trans-2-[(4-dimethylamino) styryl] benzothiazole as a probe. By comparing the behaviors of two distinct poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) block copolymers with block composition of (PEO)132-(PPO)50-(PEO)132 [F108] and (PEO)100-(PPO)65-(PEO)100 [F127] at concentrations of 5 and 10 wt %, this study systematically examines the impact of the addition of zwitterionic surfactants. Through a comprehensive set of analytical techniques, including UV-visible absorption, steady-state emission, and time-resolved fluorescence emission studies, significant alterations in the emission spectra and quantum yields were observed upon the addition of zwitterionic surfactants. These modifications suggest a dynamic equilibrium for the transitioning of dye molecules between various microenvironments within the assemblies. Additionally, dynamic light scattering, zeta potential (ζ), nuclear Overhauser effect spectroscopy, small-angle neutron scattering, cryogenic transmission electron microscopy, field emission scanning electron microscopy, and fluorescence lifetime imaging microscopy analyses have shed light on the substantial impact of surfactant incorporation on the structural properties of assemblies.

FORMULATION AND IN VITRO TESTS OF KETOPROFEN NANOSUSPENSION USING THE MILLING METHOD WITH POLYMER VARIATIONS

Objective: The aim of this research was to formulate ketoprofen nanosuspension with a variety of polymers and to compare the dissolution rate of the nanosuspensions with ketoprofen suspension. Methods: Ketoprofen nanosuspension was formulated by milling method using a different polymer such as Polyvinyl Pyrrolidone (PVP) K-30 (F1), Polyvinyl Alcohol (PVA) (F2) and Hydroxy Propyl Methyl Cellulose (HPMC) (F3). Nanosuspensions were prepared and characterized, including organoleptic, pH, particle size, zeta potential, Polydispersity Index (PI), specific gravity, crystalline state determination, physical stability at room temperature for 3 mo, and in vitro dissolution test compared with ketoprofen suspension. Results: The ketoprofen nanosuspensions with PVP K-30 and PVA showed stable preparations, while those with HPMC showed less stability, as indicated by sedimentation during storage. The particle size values of PVP K-30 and PVA were 10.004±0.03 nm; and 9.560±0.01 nm; zeta potential and polydispersity index values met the test requirements. The dissolution rate of the ketoprofen nanosuspensions was higher with a cumulative of F1, F2, and F3 were 83.35%; 85.00%, and 81.09% after 60 min, while the ketoprofen suspension was only 7.62%. Conclusion: The milling method of ketoprofen nanosuspensions with PVP and PVA has more stable physical characteristics than nanosuspension with HPMC. The ketoprofen nanosuspensions have a higher dissolution rate than the ketoprofen suspension.

Polypiperazine-Based Micelles of Mixed Composition for Gene Delivery

We introduce a novel concept in nucleic acid delivery based on the use of mixed polymeric micelles (MPMs) as platforms for the preparation of micelleplexes with DNA. MPMs were prepared by the co-assembly of a cationic copolymer, poly(1-(4-methylpiperazin-1-yl)-propenone)-b-poly(d,l-lactide), and nonionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers. We hypothesize that by introducing nonionic entities incorporated into the mixed co-assembled structures, the mode and strength of DNA binding and DNA accessibility and release could be modulated. The systems were characterized in terms of size, surface potential, buffering capacity, and binding ability to investigate the influence of composition, in particular, the poly(ethylene oxide) chain length on the properties and structure of the MPMs. Endo–lysosomal conditions were simulated to follow the changes in fundamental parameters and behavior of the micelleplexes. The results were interpreted as reflecting the specific structure and composition of the corona and localization of DNA in the corona, predetermined by the poly(ethylene oxide) chain length. A favorable effect of the introduction of the nonionic block copolymer component in the MPMs and micelleplexes thereof was the enhancement of biocompatibility. The slight reduction of the transfection efficiency of the MPM-based micelleplexes compared to that of the single-component polymer micelles was attributed to the premature release of DNA from the MPM-based micelleplexes in the endo–lysosomal compartments.

Modulating Ti coordination environment in Ti-containing materials by sulfation for synergizing with Au sites to facilitate propylene epoxidation

Modulating the coordination environment of Ti sites in Ti-containing materials to synergize with Au sites is a crucial issue to boost the process of propylene epoxidation with H2 and O2 to produce propylene oxide (i.e., HOPO), but still remains a great challenge. Herein, we report a facile strategy to tailor the coordination states and electronic properties of Ti sites. The sulfur-decorated Ti-SiO2 (i.e., Ti sites anchored onto silica) with moderate sulfur loading (Ti-SiO2-S-M) can synergize well with Au sites for the HOPO process with high activity, propylene oxide (PO) selectivity, and H2 efficiency, which are superior to those achieved on the referenced Ti-SiO2 synergizing with Au sites. Multiple characterizations, in-situ diffuse reflectance infrared Fourier transform spectroscopy of propylene and PO, PO conversion experiment, and kinetics behaviors demonstrate that the superior advantages of Ti-SiO2-S-M against Ti-SiO2 result from the increased Ti binding energy, improved hydrophobicity, and weakened acidity, which simultaneously facilitate the adsorption of propylene and promote the desorption of PO. This insight reported here could guide the rational design and optimization of Ti-containing materials to synergize with Au catalysts for propylene epoxidation.

Highly efficient Ru/CeO2 catalyst using colloidal chemical method for propane oxidation

Although supported-Ru catalysts have been widely studied for the light alkane oxidation root in their lower cost compared to Pt and Pd, developing Ru-based catalysts with high efficiency for low-temperature light alkane elimination remains a significant challenge. Herein, Ru/CeO2 catalysts were prepared utilizing the colloidal synthesis (Ru/CeO2-CS) and compared with the catalyst prepared with the traditional impregnation method (Ru/CeO2-IM) in the textural properties and catalytic propane oxidation. It was discovered that Ru/CeO2-CS sample contained a higher concentration of active Ru − O − Ce interface and oxygen vacancies attributed to the strong Ru-CeO2 interaction, which further enhanced the redox capacity. Besides, the lower valence state of Ru species and higher contents of Lewis acid sites on Ru/CeO2-CS sample boosted the adsorption, dissociation, and activation of propane, thus promoting the deep oxidation of propane to CO2 and H2O. The reaction mechanism of propane oxidation was revealed by in-situ DRIFTS, and both the catalysts showed bands related to acrylate species, suggesting that propane underwent an acrylate oxidation pathway on Ru/CeO2-CS and Ru/CeO2-IM samples. The distinct textural properties of these catalysts resulted in Ru/CeO2-CS synthesized by colloidal methods showing a T90 of 170 °C, and Ea of 50.9 ± 1.8 kJ·mol−1, markedly lower than Ru/CeO2-IM prepared with the traditional impregnation method. Apart from the activity, the Ru/CeO2-CS sample obtained superior water resistance, thermal stability, and durability. This comprehensive work provides promising insights into low-temperature propane oxidation.

ZIF-8 Porous Liquids with Different Sterically Hindered Solvents and Porous Guests for Catalytic Conversion of Carbon Dioxide.

Utilizing carbon dioxide (CO2) as a raw material is an effective way to reduce carbon emissions, and developing catalytic systems with high catalytic activity and stability is crucial for the efficient utilization of CO2. Porous liquids (PLs) with both permanent pores and fluidity have great potential in the fields of catalysis, gas sorption, and storage. Nevertheless, the catalytic performance of PLs is affected by many factors; therefore, further study is needed. Herein, we proposed a general strategy to construct a series of type III PLs with different chemical structures of sterically hindered solvents and different microstructures of porous guests. Benefiting from the unique microstructures, the as-prepared PLs exhibit great potential in catalyzing the reaction of CO2 with propylene oxide under suitable conditions. Moreover, their catalytic activity exceeds that of pure sterically hindered solvents without a porous guest loading. The influences of the nucleophilicity of the anion of the sterically hindered solvent and the microstructure of the porous guests on the catalytic activity and the catalytic stability of the PLs were analyzed. Meanwhile, the mechanism of the catalytic conversion of CO2 was proposed, which is of great significance for the design and development of the subsequent PL catalysts.

One-Pot Synthesis of Mixed-Phase MoVTeNbOx Catalysts for Selective Oxidation of Propane to Acrylic Acid.

One-pot hydrothermal synthesis assisted by sodium citrate and citric acid is developed to fabricate mixed-phased MoVTeNbOx catalysts with different phase compositions for selective oxidation of propane to acrylic acid. Structures of various catalysts are comprehensively characterized. Interfacial interactions occur among the M1 and M2 phases of mixed-phase MoVTeNbOx catalysts to exert synergistic effects on the selective production of acrylic acid. Various mixed-phase MoVTeNbOx catalysts exhibit the same type of active site on the M1-phase component, with a significantly enhanced ability to adsorb and activate propane. The propane conversion increases linearly with the density of surface site for propane adsorption, while the propene selectivity increases linearly with the density of surface site for propene adsorption. Among the synthesized catalysts, a MoVTeNbOx catalyst composed of 35.3 wt % M1 phase, 19.2 wt % M2 phase, and 45.7 wt % amorphous phase exhibits the largest density of active site and consequently the best catalytic performance with 38.9% propane conversion and 71.2% acrylic acid selectivity at 380 °C.

Damage power enhancement of fuel air explosive with typical metal hydrides additions

To study the damage power enhancement of fuel air explosive (FAE) with metal hydrides, the effects of metal hydrides (TiH2, MgH2, ZrH2) powders on shock wave and thermal damage of pure propylene oxide (PO) were explored using a 20 L spherical explosion test system combined with colorimetric thermometry technology. The experimental results showed that compared with the base metal powders, the explosion overpressures, maximum pressure rise rates and maximum average temperatures of the solid-liquid mixed fuel with the metal hydrides (TiH2, MgH2, ZrH2) powders increased by 11.04 %, 22.61 %, 4.80 % and 26.68 %, 38.18 %, 13.91 % as well as 6.85 %, 8.57 %, 1.34 %, respectively. Furthermore, the effects of metal hydride powders on the cloud explosion fuel were better than those of Al powders, and MgH2 powders had the most significant effects on the damage power enhancement of pure PO. Metal hydride powders as high-energy additives could improve the energy release characteristics of FAE.

One-step condensation synthesis of di-tertiary ammonium salt protic ionic liquid for efficiently catalytic CO2 cycloaddition reaction under cocatalyst- and solvent-free conditions

A novel protic ionic liquid di-tertiary ammonium bromide ionic liquid (DTAB-IL) was synthesized by one-step condensation at 0 ℃ with 85 % yield. DTAB-IL also exhibited effective catalytic activity for CO2 cycloaddition without cocatalyst and solvent. The catalytic reaction conditions were optimized to 90 ℃, 4 h, 1 MPa, and the yield of propylene carbonate was obtained 96 % with high selectivity 99 %. Under the optimal conditions, DTAB-IL catalyst exhibited good recyclability and universality to various epoxides. Furthermore, temperature influence and kinetic investigation for propylene carbonate synthesis were studied. The activation energy for DTAB-IL catalyzing CO2 cycloaddition reaction was 43.93 kJ/mol, and the reaction was found to follow first-order for propylene oxide. Efficient cycloaddition reaction of CO2 and epoxide was attributed to the activation of epoxide and CO2 by di-tertiary ammonium and epoxide ring-opening by bromide anion in DTAB-IL.

Study on concentration distribution and detonation characteristics of typical multiphase fuel in orthogonal flow field

The fuel concentration distribution and detonation characteristics are important for performance evaluation. In order to meet the needs of airdrop, launcher and missile, the transient flow and detonation process of multiphase fuel in orthogonal flow field are analyzed by experiments and numerical simulations. The dynamic detonation model of ethyl ether (EE), propylene oxide (PO) and tetrahydro dicyclopentadiene (JP-10) is built. The flow process, concentration distribution, overpressure, temperature and detonation wave structure of the three fuels are obtained. The results show that the falling velocity has obvious influence on the detonation process of fuel droplets. The falling velocity of 0.5 Ma makes the fuel concentration distribution more uniform and the energy output is better. The peak overpressure of EE, PO and JP-10 is 2.88 MPa, 3.21 MPa and 2.96 MPa respectively. The peak temperature is 2885 K, 3230 K and 2955 K respectively. The burn out rate increases by 8.5%, 8.1% and 13.7% respectively. JP-10 has higher sensitivity to falling velocity, and there are obvious secondary peaks of overpressure in low-speed state. PO has higher stability for falling velocity, and the scaled length of high temperature/pressure after detonation wave is 0.145 m·kg-1/3.

Characterization of Fresh, Deactivated, and Regenerated TS‐1 for Propylene Epoxidation: Investigating Surface Deactivation Species

AbstractTitanium silicalite‐1 (TS‐1) serves as an effective catalyst for propylene epoxidation in the hydrogen peroxide propylene oxide (HPPO) process, attracting wide attention from researchers and industry. Nonetheless, the TS‐1 catalyst experienced inevitable deactivation during industrial applications, which adversely impacts its lifespan. To enhance reaction stability of catalyst, the present work conducted a systematic investigation into the deactivation reason of the TS‐1 catalyst. The fresh, deactivated, and regenerated catalysts were characterized by using various analytical techniques to compare their physicochemical properties. The surface coke species of the deactivated catalysts were extracted by the Soxhlet extraction method and subsequently analyzed using GC–MS. Additionally, the pathways for by‐product formation were simulated through Gauss software. The results indicated that the so‐called coking deposits formed during the reaction predominantly consist of propylene glycol, ethers, and oligomers. These coke species covered the partial active sites on the catalyst surface, blocked the pores of the catalyst, and accordingly led to the deactivation of the catalyst, although the crystalline structure of the catalyst hardly changed after deactivation. These results provide a theoretical basis and novel insights for the rational design and development of efficient catalysts for the HPPO process.

Catalytically Active Gold Nanoparticles on Star Block Co-polymer Matrix: Synthesis of Nanocomposite Film Exploring the Langmuir-Blodgett Technique.

Nanocomposites with metal nanoparticles and block copolymers distributed in a stable and robust thin film are preferred for various applications. Here, synthesis of such a nanocomposite is reported, which is composed of gold nanoparticles (AuNPs) embedded in a tetronic 701 (T701) and 90R4 (T90R4) thin film matrix generated using the Langmuir-Blodgett (LB) thin film technique. Tetronics contain a monoprotonated central ethylenediamine group at pH 5 due to the presence of chloroauric acid (HAuCl4) in the subphase, along with poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) blocks, both of which have the capacity to serve as the reducing agent toward chloroaurate anion (AuCl4-). Calorimetric experiments have shown that T90R4 has a better interaction with AuCl4-, probably due to its better electrostatic interaction with AuCl4- ions due to the higher % of the hydrophilic PEO group. On the other hand, the T701-AuNP interaction turned out to be more spontaneous due to the higher hydrophobicity of T701 (higher PPO/PEO ratio). The optical properties and structure/morphology of these nanocomposites are characterized by UV-vis spectroscopy, FTIR spectroscopy, XRD, and TEM. The composite thin film has the ability to catalyze the organic electron transfer process between p-nitrophenol and p-aminophenol in the presence of sodium borohydride. A clear correlation has been found between the reaction rates and the kind of tetronic present in the nanocomposite, which acted as a matrix and stabilizer toward AuNPs.

Iron and Zinc Metallates Supported on Ion Exchange Resins: Synergistic Catalysts for the Solvent‐free Cyclic Carbonate Synthesis from Epoxides and CO2

Despite extensive research into developing efficient and environmentally friendly catalysts for converting CO2 over the last decade, the search for a robust and cost‐effective catalytic system is ongoing. This study describes developing and applying a new catalytic system using inexpensive ferrate and zincate anions immobilized on easily available commercial ion exchange resins (IER) to produce cyclic carbonates from CO2 with high efficiency and low cost. Two polystyrene‐based anion exchange resins, AmberlystTM A26‐Cl (A26‐Cl) and AmberliteTM IRA‐400‐Cl (IRA400‐Cl), were compared. The results demonstrated the catalysts' remarkable activity under mild conditions and demonstrated the synergistic effect between the polystyrene support and the active ammonium metallates, presenting a scalable, eco‐friendly method for cyclic carbonate production using waste CO2. A Design of Experiment approach was implemented to optimize the catalytic cycloaddition of CO2. The reaction scale‐up to produce a 5 g batch of propylene oxide and conducting recycling tests demonstrated that the catalyst retained its activity over four cycles. The research also explored the use of various epoxides and found that terminal epoxides produced very good yields. In summary, this study introduces a cost‐effective, scalable method for converting CO2 into valuable cyclic carbonates, leveraging the synergistic effects of polystyrene supports and active ammonium metallates.

A DFT and Microkinetic Study of Propylene Selective Oxidation on Cu2O(111) Surface with O2: Chlorinum Effect

AbstractSpin‐polarized density functional theory (DFT) +U calculation was performed to study propylene selective oxidation on Cu2O(111) and Cl−Cu2O(111) surfaces. The mechanism included two pathways: the allylic hydrogen stripping (AHS) pathway and the epoxidation pathway, and acrolein, propylene oxide (PO), propanal and acetone can be formed. The calculated results found that the C3H6*+OO*→OOMMP2*→PO* route can be regarded as the preferred formation route of PO on these two surfaces. On clean surface, acrolein can be regarded as the main product, then other products selectivity follows: acetone>PO>propanal. On Cl−Cu2O(111) surface, acrolein was also the main product, and the apparent activation energy of acrolein (1.97 eV) was approximated to the apparent activation energy of PO (2.04 eV), other products selectivity follows: PO>propanal>acetone, which means that the selectivity of PO can be improved by the effect of Cl. Microkinetic simulation confirm that PO selectivity can be elevated qualitatively, and found that OOMMP2*→PO2*+O* is the rate determining step on pure surface and C3H6*+OO*→OOMMP2* is the rate controlling step on the doped−Cl surface. From this work, it can be found the O−O bond in O2 can be activated effectively by the presence of Cl, enhancing the selectivity of PO.

Development of the headspace gas chromatography-tandem mass spectrometry method for ethylene oxide and ethylene chlorohydrin residue in medical devices.

Ethylene oxide (EO) sterilization is commonly employed for the sterilization of medical devices and has a very high market share. However, EO and its metabolite ethylene chlorohydrin (ECH) are toxic to humans. In compliance with the classification and residue limits of medical devices defined by ISO 10993-7, our study established two extraction methods for the testing of EO and ECH. The first method involves simulated-use extraction using water as the extraction solvent. While the second, exhaustive extraction, directly extracts sample through headspace sampling analysis. Gas chromatography-tandem mass spectrometry in multiple reaction monitoring mode was utilized, requiring only 16 min. Then, the developed method was applied to assess 10 commercially available medical devices sterilized by EO. In simulated-use extraction, calibration curves were evaluated in the range of 1-100 and 5-500 μg for EO and ECH, respectively (r > 0.999). Inter-day recoveries ranged from 85.0% to 95.2% and from 94.8% to 102.4%. In exhaustive extraction, calibration curves spanned 0.5-50 and 2-200 μg for EO and ECH, respectively (r > 0.999). Inter-day recoveries ranged from 101.6% to 102.1% for EO and from 98.1% to 102.2% for ECH. After analysis of the 10 commercially available medical devices, two cotton swabs were found to have ECH of 35.1 and 28.4μg per device, and four medical devices were found to have EO with concentration below the limit of quantification. Meanwhile, we found that the EO internal standard (propylene oxide) recommended by ISO 10993-7 had interference problems with other similar substances and was not suitable as an internal standard for EO. This study offers a sensitive and straightforward analytical approach to EO and ECH residues in a variety of medical devices. In addition, the results show that the EO or ECH content of these types of medical devices in our study falls below the regulatory limits, therefore instilling confidence among consumers regarding their safe use.

Diblock Copolymers of Poly(ethylene oxide)-b-poly(propylene oxide) Stabilize a Blood-Brain Barrier Model under Oxidative Stress.

The blood-brain barrier (BBB) is a highly restrictive barrier at the interface between the brain and the vascular system. Even under BBB dysfunction, it is extremely difficult to deliver therapies across the barrier, limiting the options for treatment of neurological injuries and disorders. To circumvent these challenges, there is interest in developing therapies that directly engage with the damaged BBB to restore its function. Previous studies revealed that poloxamer 188 (P188), a water-soluble triblock copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), partially mitigated BBB dysfunction in vivo. In the context of stabilization of the damaged BBB, the mechanism of action of PEO-PPO block copolymers is unknown, and there has been minimal exploration of polymers beyond P188. In this study, a human-based in vitro BBB model under oxidative stress was used to investigate polymer-BBB interactions since oxidative stress is closely linked with BBB dysfunction in many neurological injuries and disorders. PEO-PPO block copolymers of varied numbers of chemically distinct blocks, PEO block length, and functionality of the end group of the PPO block were assessed for their efficacy in improving key physiological readouts associated with BBB dysfunction. While treatment with P188 did not mitigate damage in the in vitro BBB model, treatment with three diblock copolymers improved barrier integrity under oxidative stress to a similar extent. Of the considered variations in the block copolymer design, the reduction in the number of chemically distinct blocks had the strongest influence on therapeutic function. The demonstrated efficacy of three alternative PEO-PPO diblock copolymers in this work reveals the potential of these polymers as a class of therapeutics that directly treat the damaged BBB, expanding the options for treatment of neurological injuries and disorders.

Synthesis of alternating polyesters using a dual catalytic system of alkali metal alkoxides and crown ether

In this study, a dual catalytic system that merges crown ether with alkali metal alkoxides (AMA) is utilized in the ring-opening alternating polymerization (ROAP) of phthalic anhydride (PA) and propylene oxide (PO). This method streamlines the production of polyesters characterized by a fully alternating sequence, a modifiable molar mass (achieving up to 59.3 kg mol−1), and a narrow molar mass distribution (ÐM < 1.26). Analysis of various commercially available AMAs, notably sodium ethoxide (EtONa), sodium methoxide, and lithium ethoxide, in tandem with crown ethers (15-crown-5 and 18-crown-6), underscores the superior catalytic efficacy of the EtONa and 18-crown-6 pairing. This heightened efficiency is attributed to the coordination of crown ether with alkali metal ions, thereby boosting the nucleophilicity of terminal alkoxide anions. The methodology has been successfully deployed in the ROAP of PA, norbornene anhydride, and multiple epoxides, while also simplifying the creation of aliphatic–aromatic block polyesters from a mixture of PA, PO, and lactide. This strategy presents a straightforward approach to polyester production, thus making significant contributions to the evolution of polyester synthesis technology.

The Role of Ligand Exchange in Salen Cobalt Complexes in the Alternating Copolymerization of Propylene Oxide and Carbon Dioxide.

A comparative study of the copolymerization of racemic propylene oxide (PO) with CO2 catalyzed by racemic (salcy)CoX (salcy = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane; X = perfluorobenzoate (OBzF5) or 2,4-dinitrophenoxy (DNP)) in the presence of a [PPN]Cl ([PPN] = bis(triphenylphosphine)iminium) cocatalyst is performed in bulk at 21 °C and a 2.5 MPa pressure of CO2. The increase in the nucleophilicity of an attacking anion results in the increase in the copolymerization rate. Racemic (salcy)CoX provides a high selectivity of the copolymerization, which can be higher than 99%, and the living polymerization mechanism. Poly(propylene carbonate) (PPC) with bimodal molecular weight distribution (MWD) is formed throughout copolymerization. Both modes are living and are characterized by low dispersity, while their contribution to MWD depends on the nature of the attacking anion. The racemic (salcy)CoDNP/[PPN]DNP system is found to be preferable for the production of PPC with a high yield and selectivity.

Synthesis and reactivity of Nb/graphene-MCM-48 and Al/graphene-MCM-48 IN CO2 chemical fixation

Mesoporous materials such as the Mobil Composition of Matter (MCM), play a crucial role in the chemical fixation of carbon dioxide (CO2). These materials exhibit a porous structure with intermediate-sized pores, providing a high surface area and a uniform pore distribution. The objective of this study is to synthesize the mesoporous material MCM-48 using the ionic solid chloride of 1-hexadecyl-3-methylimidazolium ([C16MI]Cl) as a directing agent and tetraethoxysilane (TEOS) as a silica precursor and apply this material as a catalyst in the cycloaddition reaction of CO2 to propylene oxide to produce propylene carbonate. Compounds such as graphene, aluminum, and niobium are employed in different Si/compound molar ratios (1, 5, and 10) to enhance the material properties. The Nb/Graphene-MCM-48 material with a Si/Nb ratio of 10 demonstrated the best catalytic performance in the CO2 cycloaddition, achieving a yield of 85 % and a selectivity of 99 % for propylene carbonate. The results demonstrate that MCMs are highly efficient in the selective conversion of CO2 into cyclic carbonate, offering promising applications for CO2 emission mitigation. This study advances decarbonization and sustainable development, aligning with the Sustainable Development Goals (SDGs) 3 (Good Health and Well-Being), 9 (Industry, Innovation, and Infrastructure), 12 (Responsible Consumption and Production), and 15 (Life on Land) by promoting technologies that reduce environmental impact and support sustainable industrial practices.