Nonpolar Organic Solvents Research Articles

TFE Terpolymers: Once Promising - Are There Still Perspectives in the 21st Century? Part II: Processing, Properties, Applications.

Tetrafluoroethylene (TFE) terpolymers have emerged as advantageous substitutes for polytetrafluoroethylene (PTFE). Therefore, they are being considered as alternatives to PTFE in many application areas. The advantages of TFE terpolymers include their facile processability at elevated temperatures, their solubility in some polar organic solvents, their inertness against aqueous acids, aqueous bases and a large number of mostly nonpolar organic solvents, their low dielectric constant, their low refractive index as well as useful electro- and thermochemical properties. This review on TFE terpolymers focuses on their processing including shaping and surface modification as well as on selected properties including wettability, dielectric properties, mechanical response behavior, chemical stability, and degradability. Applications including their use as elastomeric sealing material, liner and cladding layer as well as their use as material for membranes, microfluidic devices, photonics, photovoltaics, energy storage, energy harvesting, sensors, and nanothermitic composites will be discussed. The review concludes with a discussion of the future potential of TFE terpolymers and scientific challenges to be addressed by future research on TFE terpolymers.

Magnetically Separable Chiral Poly(ionic liquid) Microcapsules Prepared Using Oil-in-Oil Emulsions.

This article presents a method for producing chiral ionic liquid-based polyurea microcapsules that can be magnetically separated. The method involves entrapping hydrophilic magnetic nanoparticles within chiral polyurea microspheres. The synthetic process for creating these magnetic polyurea particles involves oil-in-oil (o/o) nano-emulsification of an ionic liquid-modified magnetite nanoparticle (MNPs-IL) and an ionic liquid-based diamine monomer, which comprises a chiral bis(mandelato)borate anion, in a nonpolar organic solvent, toluene, and contains a suitable surfactant. This is followed by an interfacial polycondensation reaction between the isocyanate monomer, polymethylenepolyphenyl isocyanate (PAPI 27), and the chiral diamine monomer, which generates chiral polyurea microcapsules containing magnetic nanoparticles within their cores. The microcapsules generated from the process are then utilized to selectively adsorb either the R or S enantiomer of tryptophan (Trp) from a racemic mixture that is dissolved in water, in order to evaluate their chiral recognition capabilities. During the experiments, the magnetically separable chiral poly(ionic liquid) microcapsules, which incorporated either the R or S isomer of chiral bis(mandelato)borate, exhibited exceptional enantioselective adsorption performance. Thus, the chiral polymeric microcapsules embedded with the R-isomer of the bis(mandelato)borate anion demonstrated significant selectivity for adsorbing L-Trp, yielding a mixture with 70% enantiomeric excess after 96 h. In contrast, microcapsules containing the S-isomer of the bis(mandelato)borate anion preferentially adsorbed D-Trp, achieving an enantiomeric excess of 73% after 48 h.

High EQE of 43.76% in solution-processed OLEDs operating at a wavelength of 626 nm

Simultaneously achieving high-efficiency, deep-red emission, and solution-processed organic light-emitting diodes (OLEDs) remains a huge challenge. In this work, a thermally activated delayed fluorescent (TADF) material of CzPXZ that exhibits aggregation-induced emission property and a deep-red phosphorescent emitter of Ir(dmppy)(piq)2(od) are developed to build effective energy transfer pathways by dissolving them in a non-polar organic solvent. The electroluminescent emission peaks of CzPXZ:Ir(III)-based OLEDs are located at deep-red 626 nm, demonstrating efficient energy transfer from CzPXZ to the Ir(III) complex. Furthermore, an optimized DPEPO hole-blocking layer is utilized in such Ir(III)-doped OLEDs to enhance the radiative recombination. Therefore, a high external quantum efficiency of 43.76% is achieved for CzPXZ:Ir(III)-based OLEDs. This work sheds light on the great potential of energy transfer from AIE-TADF to red phosphorescent emitters for high-efficiency, solution-processed, deep-red OLEDs.

Mechanism simulation of polar and nonpolar organic solvent vapor adsorption on a multiwall carbon nanotubes paper gas sensor.

We investigate the adsorption behavior of polar and nonpolar molecules on carbon nanotube interfaces through computational simulations. Gaussian 16 was utilized to calculate the total energy of each possible molecular structure and analyze the adsorption mechanisms in stacked and inline configurations. The study reveals that nonpolar molecules favor stacked adsorption on two graphene interfaces, while polar molecules prefer inline adsorption. The findings suggest that inline adsorption of polar molecules results in minimal changes to the local dielectric constant, which may explain the absence of multi-step adsorption isotherms. The research examines the stability and energetics of molecular adsorption on graphene layers simulating CNT interfaces. Different types of molecules (polar and nonpolar) exhibit distinct adsorption behaviors, with nonpolar molecules aligning with the IUPAC type VI isotherm model and polar molecules following the Langmuir isotherm model (IUPAC type I). This study provides insight into how molecules are likely to adsorb on CNT surfaces and the impact on the local dielectric constant. This understanding has implications for the design and optimization of CNT-based sensors, particularly in detecting organic solvents and gases in various environments.

Electrospun nanofibrous membranes based on fluorine-free polyimide for swift oil spill cleanup and emulsion separation

The urgent need to mitigate environmental damage caused by oil and organic pollutants in oil production industries and spill accidents necessitates effective removal methods. This study introduces novel nanofibrous membranes composed of fluorine-free polyimide, which was formed by electrospinning of BPADA-TrMPD, produced by polycondensation reaction in one-step and at high temperature using 4,4′-(4,4′-isopropylidenediphenoxy)bis-(phthalic anhydride) (BPADA) and 2,4,6-trimethyl-m-phenylenediamine (TrMPD). The resulting membranes exhibited a hydrophobic nature with a water contact angle of 114° and an oil contact angle of ∼ 0°. The adsorption performance of the nanofibers was explored using Saudi crude oil and non-polar organic solvents (i.e., n-hexane and dodecane). The developed membranes exhibited a crude oil uptake ranging from 35 to 60 g g−1 and demonstrated rapid removal capabilities, reaching equilibrium sorption capacity within a few minutes for crude oil. Moreover, these membranes displayed remarkable flux of 1991, 1508, and 206 L m−2h−1 for dodecane, n-hexane, and crude oil, respectively. The capability of the fluorine-free mats designed for oil spill cleanup was validated through its application in treating actual samples. The durability and recyclability of the membranes were showcased by regenerating them through mechanical treatment.

Computational analysis of magnetohydrodynamic ternary-hybrid nanofluid flow and heat transfer inside a porous cavity with shape effects

The current study aims to analyze the magnetohydrodynamic natural convective fluid flow and heat transmission features of the ternary-hybrid nanofluid filled the partially heated porous square cavity under the impacts of heat absorption/generation and thermal radiation. The governing equations are solved using the Marker and Cell method. In the present study, three different types of nanoparticles, such as molybdenum disulfide (MoS2), single-walled carbon nanotube (SWCNT), and silver (Ag), are suspended in an inorganic (water) or non-polar organic (kerosene) solvent. Nine different shapes of nanoparticles are utilized in this study. The outcomes show that for the fixed pertinent parameter values of the existence and nonexistence of heat generation/absorption, the MoS2+SWCNT+Ag/water ternary-hybrid nanofluids synthesized by lamina-shaped nanoparticles, the average thermal transmission rate is increased by 40.8523%, 36.329%, and 38.7025%, respectively, than sphere-shaped nanoparticles. In addition, utilizing the MoS2+SWCNT+Ag/kerosene ternary-hybrid nanofluids synthesized by lamina-shaped nanoparticles, the average heat transmission rate is augmented by 38.0322%, 33.0464%, and 35.5868%, respectively, than sphere-shaped nanoparticles. The current study reveals that the fluid flow and heat transfer efficiency are significantly increased by improving the nanoparticle volume fraction and shape factors depending upon the existence of heat absorption/generation. The high average heat transfer efficiency is observed when lamina-shaped nanoparticles are dispersed into the water compared to kerosene in the presence of a heat source. This study can enhance heat transmission efficiency in various industrial and engineering fields, such as heat exchangers, solar collectors, and fuel cells.

Fabrication of a family of porous azo polymers with multifunctional adsorption and separation performances

In this paper, a class of porous organic polymers (POPs) of p-hydroxy azobenzene with a mesoporous structure was designed and synthesized by a –NN– coupling reaction of tetraamino-metal phthalocyanine (MTAPc, where M = Co, Ni or Cu) with hydroquinone (namely Azo-MHQ, where M = Co, Ni or Cu). The Azo-MHQ materials possessed good thermal stabilities, excellent dispersibilities in water, polar and non-polar organic solvents, as well as excellent chemical stabilities. Among them, Azo-CuHQ showed an outstanding iodine trapping ability in an iodine solution and vapor with saturated adsorption capacities of 1347.47 mg g−1 and 118 wt%. In addition, Azo-CuHQ also showed a high adsorption capacity for methylene blue (MB) with the adsorption amount of 191.21 mg g−1. Furthermore, by loading Azo-CuHQ onto polyethersulfone (PES) membrane, the water permeability of the obtained membranes reached 147.03 L m−2 h−1 bar−1, and the retention rate of Ag in a very low concentration solution of 20 ppm was 56.8 %. Additionally, a thorough analysis of the Azo-CuHQ adsorption and separation mechanism was conducted. A novel approach to the design and synthesis of a class of materials with multifunctional adsorption and separation capabilities is presented in this research.

Liquid-solid interface polymerization: A simple approach for efficient polyamide/polyethylene thin film composite total heat exchange membranes construction

A simple liquid-solid interface polymerization (LSIP) strategy was developed to prepare high performance polyamide (PA) based thin film composite (TFC) total heat exchange membranes (THEMs) to avoid the use of organic solvents and surfactant during the inverse phase interface polymerization processes between piperazine (PIP) and 1,3,5-benzenetricarbonyl trichloride (TMC) on porous polyethylene (PE) substrates. The non-polar organic solvent in the TMC organic phase coated on the surface of the PE surfaces was completely removed beforehand by evaporation to form polar TMC solid coating on the PE surfaces and facilitate the quick spreading of lately added aqueous PIP solutions, forming dense and highly cross-linked PA separation layers with superior total heat recovery efficiency and CO2 barrier property. The effects of TMC loading level, PIP concentration, and LSIP reaction time on the structure and performance of PA/PE-TFC THEMs were systematically investigated, leading to the formation of THEMs 0.20P-0.10T-6 with ultra-low CO2 permeance of 0.9 GPU, and high sensible heat exchange efficiency of 94.3 %, water vapor flux of 2128 g m−2·24 h−1, and enthalpy exchange efficiency of 76.8 %.

Adhesive Zwitterionic Poly(ionic liquid) with Unprecedented Organic Solvent Resistance.

The resistance of adhesives to organic solvents is of paramount importance in diverse industries. Unfortunately, many currently available adhesives exhibit either weak intermolecular chain interactions, resulting in insufficient resistance to organic solvents, or possess a permanent covalent crosslinked network, impeding recyclability. This study introduces an innovative approach to address this challenge by formulating zwitterionic poly(ionic liquid) (ZPIL) derivatives with robust dipole-dipole interactions, incorporating sulfonic anions and imidazolium cations. Due to its unique dynamic and electrostatic self-crosslinking structure, the ZPIL exhibits significant adhesion to various substrates and demonstrates excellent recyclability even after multiple adhesion tests. Significantly, ZPIL exhibits exceptional adhesion stability across diverse nonpolar and polar organic solvents, including ionic liquids, distinguishing itself from nonionic polymers and conventional poly(ionic liquid)s. Its adhesive performance remains minimally affected even after prolonged exposure to soaking conditions. The study presents a promising solution for the design of highly organic solvent-resistant materials for plastics, coatings, and adhesives.

Solvent Tolerance Improvement of Lipases Enhanced Their Applications: State of the Art.

Lipases, crucial catalysts in biochemical synthesis, find extensive applications across industries such as food, medicine, and cosmetics. The efficiency of lipase-catalyzed reactions is significantly influenced by the choice of solvents. Polar organic solvents often result in a decrease, or even loss, of lipase activity. Conversely, nonpolar organic solvents induce excessive rigidity in lipases, thereby affecting their activity. While the advent of new solvents like ionic liquids and deep eutectic solvents has somewhat improved the activity and stability of lipases, it fails to address the fundamental issue of lipases' poor solvent tolerance. Hence, the rational design of lipases for enhanced solvent tolerance can significantly boost their industrial performance. This review provides a comprehensive summary of the structural characteristics and properties of lipases in various solvent systems and emphasizes various strategies of protein engineering for non-aqueous media to improve lipases' solvent tolerance. This study provides a theoretical foundation for further enhancing the solvent tolerance and industrial properties of lipases.

Synthesis of New Multifunctional Linolenic Acid Vanillyl Ester and Investigation of Antioxidant and Antibacterial Activities.

Vanillyl alcohol (VA) possesses potent antioxidant activity, yet its applicability is hindered by its limited solubility in emulsions or non-polar organic solvents. Conversely, long-chain polyunsaturated fatty acids exhibit antibacterial properties. The combination of these compounds offers the prospect of developing novel phenolic lipid compounds with dual antioxidant and antibacterial activities, alongside enhanced solubility capabilities. In this investigation, linolenic acid vanillyl ester (LAVE) was synthesized from VA and linseed oil (LO) through a transesterification reaction employing immobilized lipase. Optimization of LAVE production was achieved by varying reaction temperature, substrate concentration, and reaction time. LAVE demonstrated efficacy in scavenging both 2,2-diphenyl-1-picryhydrazyl and 2,2'-azino-bis (3-ethylbenthiazoline-6-sulphonic acid) radicals in organic solvents. Antioxidant testing via lipid oxidation analysis revealed that LAVE, when distributed within emulsions, effectively impeded the formation of conjugated dienes and conjugated trienes. Furthermore, LAVE exhibited antibacterial activity against four strains of spoilage bacteria: Bacillus subtilis, Bacillus coagulans, Pseudomonas fluorescens, and Alcaligenes faecalis. Zeta potential analysis substantiated the binding of LAVE to the bacterial cell surface. Propidium iodide uptake assay and fluorescence microscopy further elucidated that LAVE induces cell lysis by augmenting membrane permeability.

Characteristics of the existing methods for obtaining carotenes from carotenoid concentrates

Carotenes, which simultaneously have the properties of natural dyes and biologically active substances that have a positive effect on human health and life expectancy, are becoming increasingly widespread in the food, pharmacological and cosmetic industries. This necessitates an increase in the production of carotenes on an industrial scale. For use in food technologies, an encapsulated form of carotenes is recommended, which requires their high purity. The purpose of this study is to analyze domestic and foreign scientific, technical and patent information on existing methods for obtaining carotenes from carotenoid concentrates to determine the direction of research for the development of technology for the production of carotenes, in particular lycopene, ensuring the production of high purity lycopene from carotenoid concentrates, as well as increasing release of lycopene. The issues of using chromatographic methods for isolating lycopene, their advantages and disadvantages, as well as the use of non-polar and low-polar organic solvents for isolating lycopene from carotenoid concentrate are considered. The promising direction of research on the use of adsorption resins in the isolation of lycopene from carotenoid concentrates is noted.It has been concluded that the currently existing methods for obtaining carotenes from carotenoid concentrates, in particular lycopene, are quite technically complex and time-consuming. Some of the mallow the production of high purity lycopene, but the yield of lycopene is so low that their industrial scaling seems impractical. Taking this into account, research is being updated in the field of developing a technology for producing lycopene from a carotenoid concentrate, providing a high yield of high purity lycopene, with the possibility of its implementation on an industrial scale.

Synthesis, Characterization of New Benzopyran Pyrimidines and Study of their Solvatochromic Behaviour

Five new benzopyran pyrimidines (5a-e) were synthesized in three steps by using silica-sulphuric acid as catalyst. All the synthesized benzopyran pyrimidines with various substituents were characterized by spectroscopic techniques such as 1H NMR, 13C NMR, IR and mass spectroscopy. The structural features of these molecules containing pyrimidine ring with π-conjugated systems and various functional groups on the aromatic rings greatly influence their photophysical properties. Thus, they behave as better candidates for developing the photoelectric materials. Thus, it is proposed to synthesize, characterize and study their solvatochromic behaviour in various polar and non-polar organic solvents viz. dichloromethane, tetrahydrofuran, ethyl acetate, acetonitile and ethanol. Interestingly, all the target molecules exhibited greater Stoke’s shift (λf-λa) in dichloromethane except for compound 5e, which exhibited greater value in tetrahydrofuran, possibly due to the moderately polar nature of the solvent. The synthesized benzopyran pyrimidines displayed solvatochromic characteristics due to the presence of multiple substituted functional groups on the rings in different organic solvents. Due to their remarkable properties, they could serve as potential candidate molecules for future investigations into photoelectric materials.

Controlling the Nematic Liquid Crystallinity of Cellulose Nanocrystals with an Alcohol Ethoxy Sulfonate Surfactant.

Cellulose nanocrystals (CNCs) are biobased colloidal nanorods that have unlocked new opportunities in the area of sustainable functional nanomaterials including structural films and coatings, biomedical devices, energy, sensing, and composite materials. While selective light reflection and sensing develop from the typical chiral nematic (cholesteric, Nem*) liquid crystallinity exhibited by CNCs, a wealth of technologies would benefit from a nematic liquid crystal (LC) with CNC uniaxial alignment. Therefore, this study answers the central question of whether surfactant complexation suppresses CNC chirality in favor of nematic lyotropic and thermotropic liquid crystallinity. Therein, we use a common surfactant having both nonionic and anionic blocks, namely, oligo(ethylene glycol) alkyl-3-sulfopropyl diether potassium salt (an alcohol ethoxy sulfonate (AES)). AES forms complexes with CNCs in toluene (a representative for nonpolar organic solvent) via hydrogen bonding with an AES' oligo(ethylene glycol) block. A sufficiently high AES weight fraction endows the dispersibility of CNC in toluene. Lyotropic liquid crystallinity with Schlieren textures containing two- and four-point brush defects is observed in polarized optical microscopy (POM), along with the suppression of the cholesteric fingerprint textures. The results suggest a nematic (Nem) phase in toluene. Moreover, thermotropic liquid crystallinity is observed by incorporating an excess of AES, in the absence of an additional solvent and upon mild heating. The Schlieren textures suggest a nematic system that undergoes uniaxial alignment under mild shear. Importantly, replacing AES with a corresponding nonionic surfactant does not lead to liquid crystalline properties, suggesting electrostatic structural control of the charged end group of AES. Overall, we introduce a new avenue to suppress CNC chirality to achieve nematic structures, which resolves the long-sought uniaxial alignment of CNCs in filaments, composite materials, and optical devices.

Synthesis and Characterization of Alkyd Resin Immersed in Silver-Nanoparticle Derived from Cottonseed Oil

Alkyd resin prepared from Gossypium hirsutum (cotton seed) seed oil and immersed in silver nanoparticles has been characterized and evaluated using standard analytical methods. Gas Chromatography-Mass Spectrometry (GCMS) was used to determine the fatty acid profile of the seed oil extract which was physicochemically characterized using AOAC standard method. The results obtained are as follows: Iodine value; 102.36g I2/100g, Acid value; 3.19 mgKOH/g, Saponification value; 202.32 mg/KOH/g, Refractive index; 1.46, Specific gravity; 0.91 and Moisture content; 1.20. The alkyd resin was prepared using alcoholysis-polyesterification reaction. The prepared resin was then immersed in silver benzoate to give Gossypium hirsutum immersed silver nanoparticle alkyd resin (GHSOR-AgNps) and the formulated resin was analyzed using Ultraviolet-Visible spectroscopy (UV), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). UV-visible spectroscopy was used to analyze the silver benzoate salt. The performance of the formulated resin was assessed and revealed thus: soluble in both polar and non-polar organic solvents used in the study, dried through after 24 hours, showed chemical resistance to 0.1M NaOH with total removal, and its acid value was below 10 mgKOH/g. Therefore, Gossypium hirsutum seed oil (GHSO) has been shown to be a cost-effective, renewable and sustainable feedstock for alkyd resin production in the coating industry.

Temperature-dependent chlorosomal self-aggregation of bacteriochlorophyll-d analogs with a branched alkyl chain in a single 1-chlorooctane solvent

Abstract Recently, the supramolecular polymerization of chlorophyll pigments mimicking a natural light-harvesting apparatus (chlorosome) was demonstrated in low-polar organic solvents or aqueous solutions. To obtain the most aggregation models, a concentrated solution of the pigments in a polar organic solvent was diluted with a large amount of a nonpolar organic solvent or water. Here, bacteriochlorophyll-d analogs possessing branched alkyl chains of different lengths at the peripheral 17-propionate residue on the core chlorin π-system were prepared and their highly soluble chlorosomal supramolecules were produced in single 1-chlorooctane as a low-polar solvent. Temperature-dependent electronic absorption and circular dichroism spectroscopies were employed to analyze their self-aggregation and disaggregation mechanisms. The synthetic analogs were monomeric at high temperatures and self-aggregated during cooling of the hot solution through a non-sigmoidal pathway. The obtained chlorosomal self-aggregates were reversibly monomerized by heating the homogeneous solution. The disaggregation pathway was fitted to an isodesmic model whose melting points depended on the alkyl-chain lengths.

COSMO-RS-based assessment of thermodynamic tools in predicting the polar and non-polar solvents efficiency in vegetable oil extraction.

One of the prevalent methods for evaluating separation performance is to predict the interactions of solvent and solute molecules. The infinite dilution activity coefficient, Gibbs free energy, and sigma profiles provided insights into the solubilization of a solute and revealed the intensity of the solution's molecular interactions. The effective thermodynamic tools (infinite dilution activity coefficient, Gibbs free energy) were evaluated for predicting the efficiency of 18 polar and non-polar organic solvents in rubber seed oil (RSO) extraction. An infinite dilution activity coefficient was computed to evaluate the solubility of the rubber seed oil model compound (linoleic acid) in the organic solvents. Gibbs free energy was evaluated to show the energy change associated with the molecules mixing process and forecast the miscibility of linoleic acid molecules in the solvents. Moreover, the study examined the sigma profiles and sigma surfaces of organic solvents and linoleic acid to acquire a deeper insight into their similarities and how they interact molecularly. According to the computational prediction and experimental verification, the thermodynamic properties of Gibbs free energy and activity coefficient proved to be highly effective tools for screening polar and moderately polar solvents, predicting the molecular interactions with solute. Whereas the sigma profile and sigma surface were found to be the most efficient tools for evaluating the efficacy of non-polar solvents. Solvents with moderate polarity, such as tetrahydrofuran and diethyl ether, as well as non-polar solvents like pentane, heptane, and n-hexane, proved to be effective and favorable for oil extraction, resulting in the highest oil yields of approximately 27.0%. Overall, the COSMO-RS method demonstrates its utility in estimating the solubility of RSO in organic solvents, enabling early identification of the most effective solvent. The initial geometry optimization of every component was conducted through density functional theory (DFT) using TmoleX software. A single-point density functional theory (DFT) computation using Becke Perdew 86 (BP86) and the Triple-Zeta Valence Potential (TZVPD) was performed to produce.cosmo files. COSMO-RS calculations were performed by applying the parameterization file BP_TZVPD_FINE_19.ctd using COSMOthermX software. The practical extraction of oil from plant seeds was performed using a sonicator bath to verify the accuracy of the COSMO-RS predictions.

Evaluation of Thermodynamic and Kinetic Contributions to Over-Extraction of Extractables by Nonpolar Organic Solvents in Comparison to Lipids in Exhaustive and Exaggerated Extractions of Medical Devices Based on Abraham Solvation Model and Solvent–Material Interactions Using Low-Density Polyethylene as a Representative Material

The thermodynamic and kinetic contributions to the over-extraction of extractables by nonpolar organic solvents relative to biological lipids in exhaustive and exaggerated extractions of medical devices are studied based on the Abraham solvation model and solvent–material interactions, using low-density polyethylene (LDPE) as an exemplary material. The thermodynamic effect is evaluated by the partition constant of extractables between LDPE and extraction solvents, hexane and lipids, defined as the concentration in the polymer phase divided by the concentration in the solvent phase. The Abraham solvation model is used to correlate the measured LDPE-lipid partition constant (log10Pldpe/lipid) to construct the predictive model. Similar models are also derived from the thermodynamic cycle conversion, using the system constants of LDPE-water and Lipid-water partition systems. These constructed models, together with the predictive LDPE-hexane (log10Pldpe/hexane) model established from a previous study, are used to predict and compare the ranges and values of Pldpe/s (s = lipids and hexane) for the observed LDPE extractables over a wide hydrophobicity range in log10Po/w from zero to 30. The solvent-LDPE interactions are examined by the degree of swelling of LDPE by hexane (or other nonpolar solvents) and lipids, including the solvent diffusion rates into the material. These parameters allow the evaluation of kinetic effect on the over-extraction. The extent of over-extraction is compiled directly by experimental “overall” or “specific” migration data or indirectly calculated by the diffusion coefficient of extractables when extracted by hexane or lipids. It is concluded from this study that the extractables distribution between LDPE and lipids highly favors the lipid phase thermodynamically (Pldpe/lipid<1), and the values of Pldpe/lipid are always lower than those of Pldpe/hexane, thereby indicating that the thermodynamic effect is not the cause of over-extraction. It is the kinetic effect that dominantly contributes to the over-extraction, as supported by the material swelling and solvent diffusion rates. Finally, the extent of over-extraction has been established from a few folds to over a hundred-fold, and the median value is 7. Furthermore, the methods adopted and developed in this study can be invaluable tools in other disciplines such as the reliable prediction of extractables from other device materials and environmental sampling.

Molecularly Confined Topochemical Transformation of MXene Enables Ultrathin Amorphous Metal-Oxide Nanosheets.

Two-dimensional (2D) amorphous nanosheets with ultrathin thicknesses have properties that differ from their crystalline counterparts. However, conventional methods for growing 2D materials often produce either crystalline flakes or amorphous nanosheets with an uncontrollable thickness. Here, we report that ultrathin amorphous metal-oxide nanosheets featuring superior flatness can be realized through the molecularly confined topochemical transformation of MXene. Using MXene Ti2CTx as an example, we show that surface modification of Ti2CTx nanosheets with molecular ligands, such as oleylamine (OAm) and oleic acid (OA), not only imparts notable colloidal dispersity to Ti2CTx nanosheets in nonpolar organic solvents but also confines their subsequent oxidation to in-plane configurations. We demonstrate that unlike the drastic oxidation conventionally observed for pristine MXene, hydrophobizing MXene with OAm and OA ligands enables individual Ti2CTx nanosheets to undergo independent oxidation in a nondestructive manner, resulting in amorphous titanium oxide (am-TiO2) nanosheets that faithfully retain the dimension and flatness of pristine MXene. These am-TiO2 nanosheets exhibit exceptional activity as substrates for surface-enhanced Raman scattering. Importantly, this molecular confinement strategy can be extended to other MXene materials, providing a versatile approach for synthesizing ultrathin amorphous metal-oxide nanosheets with tailored compositions and functionalities.

Structural Information on Supramolecular Copper(II) β-Diketonate Complexes from Atomic Force Microscopy and Analytical Ultracentrifugation.

Supramolecular Cu(II) complexes were prepared from two trifunctional β-diketone ligands. The ligands (CH3Si(phacH)3 and CH3Si(phprH)3, represented by LH3) contain three aryl-β-diketone moieties joined by an organosilicon group. The complexes have the empirical formula Cu3L2, as expected for combinations of Cu2+ and L3-. Several metal-organic polyhedra (MOPs) [Cu3L2]n are possible (n = 1-10); a dodecahedron (Cu30L20; n = 10; estimated diameter of ca. 5 nm) should be the most stable because its internal bond angles would come closest to ideal values. Atomic force microscopy (AFM), performed on samples deposited from solution onto mica substrates, revealed a distribution of sample heights in the 0.5-3.0 nm range. The most commonly observed heights were 0.5-1.5 nm, corresponding to the smallest possible molecules (Cu3L2, i.e., n = 1). Some molecular cubes (Cu12L8; ca. 2.5 nm) or larger molecules or aggregates may be present as well. Equilibrium analytical ultracentrifugation (AUC) was also used to probe the compounds. A previously reported reference compound, the molecular square Cu4(m-pbhx)4 (M = 2241 g mol-1), behaved well in AUC experiments in four nonpolar organic solvents. AUC data for the new tris(β-diketonate) MOPs [Cu3L2]n in toluene and fluorobenzene did not agree well with the theoretical results for a single solute. The data were fit well by a two-solute model, but these results were not consistent in the two solvents used, and some run-to-run variability was noted even in the same solvent. Also, the calculated molecular weights differed significantly from those expected for [Cu3L2]n ([Cu3(CH3Si(phac)3)2]n, multiples of 1322 g mol-1; or [Cu3(CH3Si(phpr)3)2]n, multiples of 1490 g mol-1).