Solvent Matrix Research Articles

Purified meta-Cresol Purple dye perturbation: How it influences spectrophotometric pH measurements

Ocean acidification, a phenomenon of seawater pH decrease due to increasing atmospheric CO2, has a global effect on seawater chemistry, marine biology, and ecosystems. Ocean acidification is a gradual and global long-term process, the study of which demands high-quality pH data. The spectrophotometric technique is capable of generating accurate and precise pH measurements but requires adding an indicator dye that perturbs the sample original pH. While the perturbation is modest in well-buffered seawater, applications of the method in environments with lower buffer capacity such as riverine, estuarine, sea-ice meltwater and lacustrine environments are increasingly common, and uncertainties related to larger potential dye perturbations need further evaluation. In this paper, we assess the effect of purified meta-Cresol Purple (mCP) dye addition on the sample pH and how to correct for this dye perturbation. We conducted numerical simulations by incorporating mCP speciation into the MATLAB CO2SYS program to examine the changes in water sample pH caused by the dye addition and to reveal the dye perturbation mechanisms. Then, laboratory experiments were carried out to verify the simulation results. The simulations suggest that the dye perturbation on sample pH is a result of total alkalinity (TA) contributions from the indicator dye and chemical equilibrium shifts that are related to both the water sample properties (pH, TA, and salinity) and the indicator dye solution properties (pH and solvent matrix). The laboratory experiments supported the simulation results; the same dye solution can lead to different dye perturbations in water samples with different pH, TA, and salinity values. The modeled adjustments agreed well with the empirically determined adjustments for salinities >5, but it showed greater errors for lower salinities with disagreements as large as 0.005 pH units. Adjustments are minimized when the pH and salinity of the dye are matched to the sample. When the dye is used over a wide range of salinity, we suggest that it should be prepared in deionized water to minimize the dye perturbation effect on pH in the fresher sample waters with less well-constrained perturbation adjustments. We also suggest that the dye perturbation correction should be based on double dye addition experiments performed over a wide range of pH, TA, and salinity. Otherwise, multiple volume dye addition experiments are recommended for each sample to determine the dye perturbation adjustment. We further create a MATLAB function dyeperturbation.m that calculates the expected dye perturbation. This function can be used to validate empirically-derived adjustments or in lieu of empirical adjustments if dye addition experiments are unfeasible (e.g., for historical data). This study of dye perturbation evaluation and correction will improve the accuracy of the pH data, necessary for monitoring the long-term anthropogenic-driven changes in the seawater carbonate system.

Graphitic carbon nitride-reinforced polymer ionic liquid nanocomposite: a novel mixed-mode sorbent for microextraction in packed syringe

ABSTRACT In this paper, a novel sorbent consisting of graphitic carbon nitride/polymer ionic liquid connected to halloysite nanotubes (g-C3N4-IL@HNT) was fabricated and used for benzene and phenol pollutant extraction from water samples. This mixed-mode sorbent contains multifunctional groups that allow interaction with several analytes, and because of its porosity, it can be embedded in a syringe device as the extractant without any filtration or centrifugation steps. A high-performance liquid chromatography-ultraviolet was used for the detection of analytes. The composition and morphology of the sorbent have been investigated by Fourier-transform infrared spectroscopy, scanning electron microscopy and energy-dispersive spectroscopy. In this work, parameters affecting the extraction methodology such as elution solvent and its volume, number of absorption cycles, number of solvent cycles, salt effect and matrix effect were investigated and optimised. Under the optimal conditions, a linear calibration curve was obtained in the range of 5–1000 μg L−1 (r 2 > 0.996) with detection limits (S/N = 3) of 0.5–1 μg L−1. The g-C3N4-IL@HNT showed proper characteristics for the extraction of benzene and phenol pollutant residues in the environmental water samples with recoveries between 71% and 104.8% and the relative standard deviation of 6.6–8.6% (intra-day) and 9–11% (inter-day).

Highly transparent and flexible surface modified chitin nanofibers reinforced poly (methyl methacrylate) nanocomposites: Mechanical, thermal and optical studies

Surface modified chitin nanofibers (SMCNFs) were easily prepared by reacting chitin powder with dodecenyl succinic anhydride (DDSA) and mechanical treatment. The resulted SMCNFs were homogenously dispersed in a series of organic solvents since more hydrophobic group was introduced on the surface of chitin nanofibers. Poly (methyl methacrylate) (PMMA)/SMCNFs nanocomposite films were prepared by simple solution casting method. The homogenous dispersion of the SMCNFs in the PMMA matrix was facilitated, due to the presence of hydrogen bonding and hydrophobic interactions between the nanofillers and the PMMA matrix. Thus, PMMA/SMCNFs nanocomposite films shown high optical transparency, which were nearly the same as the transmittance of the neat PMMA film. Tensile testing results revealed that, inclusion of SMCNFs in the PMMA matrix yielding a more fracture strain and tougher films than the neat PMMA film. Thermal analysis of the neat PMMA and nanocomposite films demonstrated that, the thermal stability of PMMA was significantly enhanced upon inclusion of SMCNFs. The remarkable reinforcement effect of SMCNFs in enhancing the mechanical and thermal properties of PMMA without altering its transparency was resulted from their crystallinity, high aspect ratio, and homogenous dispersibility in the DMF solvent and PMMA polymer matrix.

Evaluation of Matrix Effect of Chilli, Cabbage and Bitter Gourd in Multiclass Multi-pesticide Residue Analysis Using Gas Chromatography Mass Spectrometry (GC-MS)

Matrix effect of twenty three (23) multi-class pesticides in three different vegetables (Bitter gourd, Chilli, Cabbage) was evaluated using modified QuEChERS [Quick (Qu), Easy (E), Cheap (Ch), Effective (E), Rugged (R) and Safe (S)] coupled with GC-MS analysis. Validation parameters (linearity, LOD, LOQ, accuracy and precision) were determined for multi-residue analysis. The Horwitz ratio was used to explain for intra-laboratory precision. The matrix effect (% ME) for each pesticide in each vegetable was assessed based on the study of slope ratio of linearity curves obtained from solvent and respective vegetable matrix. Most of the compounds had positive matrix effect and cabbage was found to be the least sensitive matrix compared to others. Recovery study was carried out fortifying pesticide mixture prepared from both pure solvent and matrix. The values of recovery percentages were satisfactory when calculated with matrix matched standard mixture (79% to 108%), with an acceptable relative standard deviation (RSD) (<20%). The results of the present study truly revealed the influence of matrix in pesticide residue estimation.

Matrix-filler interactions and solvent sorption features of nanohydroxyapatite (nHA) embedded ethylene-co-vinyl acetate (EVA)-millable polyurethane (MPU) blends.

We report the solvent sorption features and matrix filler interactions of nanohydroxyapatite (nHA) embedded ethylene-co-vinyl acetate (EVA)-millable polyurethane (MPU) blends, using toluene, xylene, and t-butylacetate as probe molecules. The EVA/MPU blends were initially loaded with different quantities of n-HA, and the interfacial interactions were evaluated through FTIR and XRD techniques. The modulation of solvent resistance was subsequently examined in terms of filler loading, temperature and molar volume of the probes. With an increase in the amount of nHA, the solvent resistance of the matrix has been found to be enhanced, with the mechanism of transport regularly deviating from the conventional Fickian mode normally followed by elastomer matrices. The Flory-Rehner equation was employed to compute the molecular mass between crosslinks (Mc) and the crosslink density (γ). The observed enhancement in the crosslink density and the degree of reinforcement has been attributed to the increased polar-polar interactions after nHA loading into the matrix. The experimentally obtained values of Mc have been compared with phantom and affine models, to identify the type of deformation happening under solvent stress. The reinforcement effect within the matrix, as a function of filler loading, has been verified by using the Kraus equation. The swelling resistance of the composites has also been verified in biological fluids in view of the possible biofield applications of the composites.

Method to quantify the in vivo skin penetration of topically applied materials based on confocal Raman spectroscopy

AbstractThis article describes a unique noninvasive capability to determine the concentration (in mg/cm3) and total amount of topically applied materials in the skin (in μg/cm2 of skin surface). It is based on in vivo confocal Raman spectroscopy. A theoretical derivation is given of a general method to calculate a concentration ratio from a Raman spectrum of a material in a medium, which can be a solvent or other matrix, such as the skin. A practical implementation of the method is then presented along with a clarification of the assumptions used and applied to a quantitative analysis of the in vivo skin penetration of trans‐retinol and propylene glycol (PG). A comparison was made between the concentrations profiles of retinol and PG found in the skin and the concentrations of retinol and PG that had been applied to the skin. Determination of the amount of these materials in the skin at different timepoints after topical application also enabled a straightforward calculation of the flux of materials into the skin (in μg cm−2 h).

Diffusion of Gold Nanoparticles in Inverse Opals Probed by Heterodyne Dynamic Light Scattering

The diffusive behavior of nanoparticles inside porous materials is attracting a lot of interest in the context of understanding, modeling, and optimization of many technical processes. A very powerful technique for characterizing the diffusive behavior of particles in free media is dynamic light scattering (DLS). The applicability of the method in porous media is considered, however, to be rather difficult due to the presence of multiple sources of scattering. In contrast to most of the previous approaches, the DLS method was applied without ensuring matching refractive indices of solvent and porous matrix in the present study. To test the capabilities of the method, the diffusion of spherical gold nanoparticles within the interconnected, periodic nanopores of inverse opals was analyzed. Despite the complexity of this system, which involves many interfaces and different refractive indices, a clear signal related to the motion of particles inside the porous media was obtained. As expected, the diffusive process inside the porous sample slowed down compared to the particle diffusion in free media. The obtained effective diffusion coefficients were found to be wave vector-dependent. They increased linearly with increasing spatial extension of the probed particle concentration fluctuations. On average, the slowing-down factor measured in this work agrees within combined uncertainties with literature data.

Impact of essential-oil-based cleaning products on indoor air quality: From liquid composition to test emission chamber

As society has become aware of health hazards related to the exposure to chemicals, major efforts have been made to address indoor air current problematic. Consequently, popularity of “green” cleaning products has upsurge. These products are formulated with essential-oils relying on their anti-bacterial properties to improve indoor air quality. Indeed, essential oils might contain a hundred of odorous molecules, mainly terpenes and terpenoids (TerVOCs) which acts as antibacterial agents. Nonetheless, do essential-oil-based products really contribute to indoor air quality improvement? This study is addressed to evaluate emissions from the use of essential-oils-based cleaning products by various scale experiments. Firstly, a correlation of liquid composition from 7 natural cleaning products with their emission potentials has been investigated. Volatile fractions are evaluated by using micro-chamber testing. A total of 28 terpenes are quantified among products in the liquid form. Nevertheless, only 22 species are detected in gas samples with a yield ranking from 9.1 % to 99.8 %. Results do not verified a direct correlation between liquid mass and emitted concentrations of terpenes. Indeed, chemical affinities between terpenes and solvent matrix in product formulation are evidenced. Then, 4 products from different cleaning purposes have been selected for emission evaluation in a test chamber of 1-m3. Product application process are correlated to real case scenario regarding applied quantity and loading factor. Emitted terpenes and carbonyl compounds are quantified by off-line and on-line chromatography measurements. Results evidenced that peak concentrations from terpenes reached up to 1.5 h after cleaning activity. Major compound emitted concentration range from 121 to 152 μg/m3, in the test chamber, for different product categories. Specific emission dynamic is evidenced for formaldehyde, in where continuous increasing concentration is revealed due to the presence of formaldehyde releasers. This study contributes to further assessment of exposure hazards related to cleaning activities.

Relationship between Structure, Functionality, and Viscosity for Aerosol-Mimicking Solutions Containing Ammonium Sulfate, Glyoxal, and a Series of Oxidized C1–C5 Compounds

The physical properties of aqueous secondary organic aerosol (SOA) can be influenced by the chemical composition of the solvent matrix within which SOA-forming reactions take place. The chemical structure and functionality of perturbing solutes on solution viscosity in bulk-phase SOA-modeling reaction mixtures containing glyoxal and ammonium sulfate were measured for a series of oxidized C1–C5 compounds. In general, as the solute concentration increased, solution viscosity increased, with the magnitude of those increases dependent upon the solute species added. The presence of glyoxal increased viscosity in about 50% of mixtures as a result of specific solute/solvent/product interactions. The oxygen/carbon (O/C) ratio was found to have a linear relationship with relative viscosity at a high solute concentration such that every −CH2CH2OH moiety addition increased solution viscosity by 25%. Solutes with identical O/C ratios but different structural characteristics (for example, acetone, 1-propanol, and 2-propanol) showed 7–8% differences in viscosity as a function of the chain length or ability to act as a hydrogen bond donor. The addition of an alcohol group increased viscosity by 10–20% over hydrogen or methyl groups in the same position. The solute structure appears to play a role in mediating intrasolvent interactions, and increases in hydrogen bonding and intersolute interactions lead to increased bulk solution viscosity, as shown in a series of experiments varying the timing and order of solute addition. These solutes are models for oxidized aerosol components, and the structure-dependent results suggest the importance of the aqueous layer functional group presence on aerosol physical properties, such as viscosity.

Optimization of multi-residue method for targeted screening and quantification of 216 harmful chemicals in plastic children’s toys by gas chromatography-tandem mass spectrometry analysis

Herein, we report a multi–residue method based on dissolution–precipitation extraction combined with gas chromatography-tandem mass spectrometry (GC–MS/MS) analysis for targeted screening and quantification of 216 harmful chemicals in plastic children’s toys. We established a spectrogram database containing the first-order mass spectra of all analytes and their second-order mass spectra at different collision energies. Good separation was attained in less than 60 min. As a simple and low–cost extraction method, dissolution–precipitation exhibited good recoveries for the analytes in the plastic samples. The matrix–matched standard curves were accurate for analyte quantification in specific plastics due to the solvent effects and matrix effects. The limits of quantification range were 0.1 mg/kg to 10 mg/kg. A wide linear range of 0.1–200 mg/kg was also observed, with r2≥0.9924. The average recoveries ranged from 63.9% to 137.6%, and the relative standard deviation (n = 6) varied from 0.6% to 13.2%. Finally, 31 ABS actual toys and 30 PVC actual toys were detected and 20 analytes with contents ranging from 0.4 mg/kg to 172 mg/kg and 30 analytes from 0.8 mg/kg to 141,030 mg/kg were discovered respectively.

Simplified Fabrication for Ion-Selective Optical Emulsion Sensor with Hydrophobic Solvatochromic Dye Transducer: A Cautionary Tale.

It has recently been reported that polystyrene microbeads may be modified to realize plasticizer-free ion-selective optical sensors (optodes) on the basis of solvatochromic dye transducers. We show here that the functionalized microbeads, individually isolated by flow cytometry, exhibit unexpectedly poor fluorescent properties and that the sensor response is instead attributed to the supernatant. A more thorough study reveals that such optical microemulsion sensors can be made operationally functional and chemically selective, seemingly in the absence of any solvent matrix or added surfactant. Instead, it is shown that residual THF used in the fabrication of the emulsified sensors may solubilize the sensing components and give a functional optode response. To evaluate this further, the number of sensing components was stepwise simplified to assess their need. Variation of residual THF levels has no effect on the ion optode response when plasticizer is present, in support of established results. Lipophilic solvatochromic dye transducers are also shown not to require an added surfactant as their nature already endows the emulsified sensors with a stabilizing ionic surface charge. The ionophores are shown to exhibit much larger stability constants in the surfactant-free formulations than surfactant-based ones (valionomycin, log β > 9.2 compared to 6.1; Na+-ionophore X, 6.7 vs 4.7), which is attributed to a less polar solvent environment for the ionophore. Potassium-, sodium-, and calcium-selective sensors were used as model systems in this study.

Review on Thermal Conductivity of the Graphene Reinforced Resin Matrix Composites

Graphene is a two-dimensional nanostructure filler with high thermal conductivity (5000 W/mK) and excellent mechanical properties, which has a very wide application prospect. Graphene is with super high specific surface area, which provides a greater contact area with polymer matrix. Then it is more easy to form the thermal conductive heat channels, which could improve the thermal conductivity of composite materials. The concentration, the ratio of geometrical diameters, the dispersion in the matrix and the interfacial bonding between graphene and the matrix materials will greatly affect the thermal conductivity of graphene reinforced composites. However, the graphene nanosheets can be easy to stack together and difficult to be dispersed into the solvent and polymer matrix. In order to improve the interfacial combination between graphene nanosheets and the matrix so as to reduce the interfacial thermal resistance of the composites, it is usually to modify the surface of graphene nanosheets, which mainly includes non-covalent modification and covalent modification. In this paper, researches on the thermal conductivity of graphene were reviewed, and the existing problems and the future research focus were also discussed.

A spin-thermodynamic approach to characterize spin dynamics in TEMPO-based samples for dissolution DNP at 7 T field.

The spin dynamics of dissolution DNP samples consisting of 4.5 M [13C]urea in a mixture of (1/1)Vol glycerol/water using 4-Oxo-TEMPO as a radical was investigated. We analyzed the DNP dynamics as function of radical concentration at 7 T and 3.4 T static magnetic field as well as function of deuteration of the solvent matrix at the high field. The spin dynamics could be reproduced in all cases, at least qualitatively, by a thermodynamic model based on spin temperatures of the nuclear Zeeman baths and an electron non-Zeeman (dipolar) bath. We find, however, that at high field (7 T) and low radical concentrations (25 mM) the nuclear spins do not reach the same spin temperature indicating a weak coupling of the two baths. At higher radical concentrations, as well as for all radical concentrations at low field (3.4 T), the two nuclear Zeeman baths reach the same spin temperature within experimental errors. Additionally, the spin system was prepared with different initial conditions. For these cases, the thermodynamic model was able to predict the time evolution of the system well. While the DNP profiles do not give clear indications to a specific polarization transfer mechanism, at high field (7 T) increased coupling is seen. The EPR line shapes cannot clarify this in absence of ELDOR type experiments, nevertheless DNP profiles and dynamics under frequency-modulated microwave irradiation illustrate the expected increase in coupling between electrons with increasing radical concentration.

Effect of solvent–matrix interactions on structures and mechanical properties of micelle‐crosslinked gels

ABSTRACTPrevious studies on hydrogels crosslinked by acrylated PEO99–PPO65–PEO99 triblock copolymer (F127DA) micelles demonstrate outstanding strength and toughness, which is attributed to the efficient energy dissipation through the hydrophobic association in the micelles. The current study further focuses on how the solvent property affects the structures and the mechanical properties of F127DA micelle crosslinked polyacrylamide gels. Binary solvents comprised of dimethyl sulfoxide (DMSO) and water are used to adjust the polymer/solvent interactions, which consequently tune the conformations of the polymer chains in the network. The presence of DMSO significantly decreases the strength but increased the stretchability of the gels, whereas the overall tensile toughness remained unchanged. In situ small‐angle X‐ray scattering measurements reveal the deformation of micelles along with the stretching direction. A structure evolution mechanism upon solvent change is proposed, according to the experimental observations, to explain influence of solvent quality on the mechanical properties of the micelle‐crosslinked gels. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 473–483

Kinetic Significance of Proton–Electron Transfer during Condensed Phase Reduction of Carbonyls on Transition Metal Clusters

Kinetic measurements, competitive hydrogenation, and H–D kinetic isotopic studies confirm the prevalence of proton–electron transfer events during the catalytic reduction of aliphatic carbonyls (C3–C6) at protic solvent and transition-metal (Ru, Pt, and Pd) interfaces. Polar protic solvents assist with the initial, rapid H-adatom ionization, which forms a proton and an electron pair. The proton shuffles through the solvent matrix and attacks the carbonyl oxygen in a quasi-equilibrated step, resulting in the formation of a charged hydroxy intermediate as the most abundant reactive intermediate. Subsequently, this intermediate undergoes a kinetically relevant H-adatom addition on the carbon atom that forms the charged alcohol, which then recombines with the electron and desorbs as the alcohol product. As a direct consequence of the initial, quasi-equilibrated proton transfer, the first-order rate coefficient increases exponentially as the gas-phase proton affinity of the carbonyls increases or as the invers...

Ag nanoaggregates as efficient broadband sensitizers for Tb3+ ions in silica-zirconia ion-exchanged sol-gel glasses and glass-ceramics

In this paper we report the study of down-shifting silica-zirconia glass and glass-ceramic films doped by Tb3+ ions and Ag nanoaggregates, which combine the typical spectral properties of the rare-earth-ions with the broadband sensitizing effect of the metal nanostructures. Na-Tb co-doped silica-zirconia samples were obtained by a modified sol-gel route. Dip-coating deposition followed by annealing for solvent evaporation and matrix densification were repeated several times, obtaining a homogeneous crack-free film. A final treatment at 700 °C or 1000 °C was performed to control the nanoscale structural properties of the samples, resulting respectively in a glass (G) or a glass-ceramic (GC), where tetragonal zirconia nanocrystals are surrounded by an amorphous silica matrix. Ag introduction was then achieved by ion-exchange in a molten salt bath, followed by annealing in air to control the migration and aggregation of the metal ions. The comparison of the structural, compositional and optical properties are presented for G and GC samples, providing evidence of highly efficient photoluminescence enhancement in both systems, slightly better in G than in GC samples, with a remarkable increase of the green Tb3+ PL emission at 330 nm excitation: 12 times for G and 8 times for GC samples. Furthermore, after Ag-exchange, the shape of Tb3+ excitation resembles the one of Ag ions/nanoaggregates, with a broad significant absorption in the whole UV-blue spectral region. This broadband enhanced downshifting could find potential applications in lighting devices and in PV solar cells.

Mimicking DNA alkylation: Removing genotoxin impurities from API streams with a solvent stable polybenzimidazole-adenine polymer

This study reports the application of a novel polybenzimidazole (PBI) polymer modified with an alkylated DNA base - adenine - as an effective scavenger for several families of DNA alkylating agents. This new material addresses an important issue in active pharmaceutical ingredients (APIs) manufacture, the removal of genotoxic impurities (GTIs) to strictly low regulated limits. Instead of targeting individual GTIs removal, PBI-adenine scavenger mimics the concept of DNA-GTI adduct formation that takes place in vivo, but in this case, in an organic solvent matrix where APIs are chemically synthesized. Removal of eleven GTIs from five different chemical families is assessed with >80% removal. Slow binding kinetics for some GTIs at room temperature was identified as one of the limitations of the PBI-adenine polymer. API purification is addressed and an efficient process is presented for two APIs studied, mometasone furoate and betamethasone acetate, affording high impurity removals (>96%) and high API recovery with low API loss (3.5%) for these case studies. The possible application of this straightforward strategy in API post-reaction stream purification, is able to attain GTI imposed limits as low as 0.6 mg GTI/g API respecting the Threshold of Toxicological Concern (TTC) value.

Effect of Volume Fraction on the Coarsening of Pb Nanophase in Al-Pb Nanocomposite Alloys Prepared by High Energy Ball Milling

The effect of volume fraction on the coarsening of Pb nanophase in Al-Pb nanocomposite alloys prepared by high energy ball milling has been studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The coarsening of Pb nanophase with different volume fractions in Al-Pb nanocomposite alloys follows the cubic growth law even though the size of the constituent phase is in nanometer range. The coarsening rate of Pb nanophase increases distinctly as the volume fraction increases, and the variation of coarsening rate is greater than the theoretical prediction in this composition range. The activation energy for coarsening of Pb nanophase does not vary with volume fraction. The coarsening of Pb nanophase is controlled by grain boundary diffusion for solute atoms in solvent matrix.

Non-isothermal crystallization kinetics of Poly(Butylene succinate) (PBS) nanocomposites with different modified carbon nanotubes

In this study, the effect of surface modification (acid treatment and chemical modification) of multi-walled carbon nanotubes (MWCNT) on the non-isothermal crystallization kinetics of poly (butylene succinate) (PBS) was studied. The chemical modifications of MWCNTs were conducted by using alcohols having different molecular weights. A twin screw microcompounder was used to prepare the MWCNT based nanocomposites. The filler content was 0.50% and 1% by weight. Fourier transform infrared spectroscopy (FTIR) was used to analyze changes in the surface chemical bonding and structure of the MWCNT's before and after surface modification processes. Transmission electron microscopy (TEM) was used to evaluate the morphological structures on the surfaces of the functionalized MWCNTs. The dispersions of surface modified and unmodified MWCNTs in PBS matrix and different solvents were characterized by scanning electron microscope (SEM) and polarized optical microscopy (POM), respectively. Different kinetic approaches such as Avrami, Ozawa and combined Avrami and Ozawa were studied to examine the non-isothermal crystallization kinetics of PBS and its nanocomposites. The nucleation activity of MWCNT nanoparticles was investigated in terms of Dobreva and Gutzow models. Activation energies for crystallization of PBS and its nanocomposites were evaluated by Friedman model. Besides, POM equipped with a hot-stage was used to examine the morphology during the crystal growth. FTIR and TEM analysis showed that surface modification of MWCNTs successfully accomplished. It was obtained that chemically modified MWCNT nanoparticles were well dispersed in both organic solvent and PBS matrix. Kinetic analysis revealed that crystallization rate of PBS increased especially in the presence of pristine MWCNT and chemically modified MWCNT nanoparticles. Moreover, crystallization rate of PBS increased as the length of the alkyl chains grafted onto the surface of MWCNT increased after chemical modification with alcohols. Pristine MWCNT exhibited the highest nucleation activity for PBS. POM analysis showed that nucleation density was higher in the presence of both pristine and chemically modified MWCNT filled PBS nanocomposites.

Polarized Optoelectronics of CsPbX3 (X = Cl, Br, I) Perovskite Nanoplates with Tunable Size and Thickness

AbstractLow dimensional semiconductor nanomaterials have shown their tailorable properties for a variety of promising applications in decades. Here a general strategy to synthesize all‐inorganic CsPbX3 (X = Cl, Br, I or their mixture) perovskite 2D nanoplates by introducing additional metal halides MX'2 or MX'3 (M = Cu, Zn, Al or Pb, etc.; X' = Cl, Br or I) is reported. These CsPbX3 perovskite nanoplates have uniform thickness and tunable size, which can be feasibly controlled by the component and ratio of the metal halides, temperature, time, and ligands. The well‐defined morphology of the nanoplates makes them ideal building blocks for the self‐assembly in the face‐to‐face and column‐by‐column arrangement. Compared to the optically isotropic CsPbX3 nanocubes, the 2D CsPbX3 nanoplates exhibit remarkable polarized UV–vis absorption and photoluminescence not only in liquid solvent and solid resin matrix, but also in self‐assembled films. An optoelectronic photodetector sensitive for linear polarized light is fabricated to demonstrate the proof‐of‐concept.