Polarized Optical Microscopy Research Articles

The Crystallization Morphology and Conformational Changes of Polypropylene Random Copolymer Induced by a Novel β-Nucleating Agent.

The crystal morphology and conformational changes during crystallization of a polypropylene random copolymer (PPR) are the basis for understanding its crystallization process. In this work, novel rare-earth β-nucleating agent WBN-28 was directly added into PPR to induce β-crystallization. The results of differential scanning calorimetry (DSC) showed that it has an excellent β-crystal-induced effect. The β-crystal content could surpass 85%, calculated from wide-angle X-ray diffraction (WAXD) data. The morphology of the β-crystal and α-crystal was intuitively observed via a polarizing optical microscope (POM). The β-crystallites were interconnected to naturally develop plate-like crystalline regions possessing a certain size, and the α-crystallites with sufficient thicknesses possessed a cross-hatched phenomenon. The bundle-like supramolecular structure of the β-crystal induced by WBN-28 was further observed via a scanning electron microscope (SEM). The conformational changes in the crystallization process of PPR were resolved via high-resolution infrared spectroscopy to understand its β-crystallization in depth. The conformational changes during the crystallization of PPR were found to be different from those of the isotactic polypropylene homopolymer (PPH); they had their own characteristics. This will provide guidance for understanding the β-crystallization of PPR in depth.

Single ferroelectric liquid crystal compounds targeted for optical voltage sensing

Nine compounds containing fluorine or chlorine atoms in the lateral position in the rigid core with a chiral terminal octyloxy-chain were synthesized mainly using Suzuki-Miyaura coupling, Mitsunobu, hydrogenation, and esterification reactions. New compounds were investigated using polarized optical microscopy (POM), differential scanning calorimetry (DSC), spectrophotometry, and electro-optical methods. A computational analysis of the effect of lateral substitution by halogen atoms on the phenyl ring on the dipole moment of the compound was provided and discussed. The designed compounds exhibit a wide temperature range of the ferroelectric phase (>40.0 °C), a low melting point (in most cases below 50.0 °C), low melting enthalpy (around 10.0–20.0 kJ/mol), a short helical pitch (in most cases below 200 nm at room temperature) and high tilt angle that ensures a cone angle of up to 90°; all those properties make them of great potential for the deformed helix ferroelectric (DHF) mode. Revealed features allow synthesized compounds in fully integrated polarization-based photonic transducers to have excellent linearity and the highest sensitivity observed in ferroelectric liquid crystals for DHF mode. For the first time, the DHF effect was reached for the single molecule FLC material in a broad temperature range down to 38 °C. These findings pave the way for a new class of optical sensors for, among others, industrial monitoring networks and brain/machine interfaces with unprecedented performance.

Effect of high hydrostatic pressure pretreatment on physicochemical properties, bioactive components and antioxidant activities of dehydrated yam slices

High hydrostatic pressure (HHP) treatment has been widely used to achieve the desired safety and quality of food products during the past two decades. In this work, effects of HHP (100–600 MPa) pretreatments on physicochemical properties, bioactive components and antioxidant activities of dehydrated yam slices were studied. The results indicated that HHP pretreatments dramatically improved the hardness, crispness, integrity ratio, and total color change of the dehydrated yam slices, while significantly inhibited their rehydration ratio when the pressure was ≥200 MPa. According to the results of scanning electron microscopy (SEM), optical microscopy (OM), and polarized optical microscopy (POM), HHP could induce the indentations and cracks of partly starch granules surface, but without any starch gelatinization. Compared with the control sample, higher total polyphenols compounds (TPC) and allantoin content were observed in the HHP pretreated samples, and the 200 MPa pretreated sample had the highest TPC and allantoin which reached 0.45 mg GAE/g and 5.47 mg/g dry weight, respectively. Furthermore, the antioxidant analysis showed that 100 and 200 MPa pretreatment could effectively enhance the antioxidant capacity of the yam slices. The above results suggested that HHP pretreatment, especially under 200 MPa, could be an appropriate assist for preparation of high-quality dehydrated yam slices.

Effect of Laterally Substituted Methoxy Group on the Liquid Crystalline Behavior of Novel Ester Molecules

Background: The aim of this research is to study the effect of length-to-width ratio on mesomorphism to enhance the understanding of its potential applications. This will be achieved by synthesizing a unique and innovative series of identical ester molecules, including lateral methoxy groups and terminal ethyl benzoate groups. In this research, we aim to find new insights into the relationship between molecular structures and mesomorphic behaviors, which could have significant implications for the development of advanced materials with adapted properties. : The objective of the study is to investigate the mesophase behavior of new ester mesogens and determine how they are influenced by lateral methoxy groups. By identifying the underlying perspectives and relationships between these variables, we hope to better understand the unique properties and potential applications of these materials. Method: In this research work, the focus is on the synthesis of ethyl(E)-4-((3-(4-alkoxy-3- methoxyphenyl)acryloyl)oxy)benzoate, which is prepared from Steglich esterification method by using (E)-3-(4-alkoxy-3-methoxyphenyl)acrylic acid and ethyl 4- hydroxybenzoate. Synthesis processes involve precise reaction sequences designed to ensure maximum yield and purity of the final product. By providing a detailed report on the experimental process, this study contributes to the ongoing research efforts aimed at the development of innovative compounds with various applications in liquid crystals Result: A new set of liquid crystal derivatives has been synthesized and studied to investigate the effect of molecular structure on the behavior of liquid crystals, with particular attention to the group -OCH3 located laterally. This series was composed of 12 derivatives (C1-C16). Among them, the first six derivatives (C1-C6) did not have the characteristics of a liquid crystal, while the remaining derivatives (C7 and C8) had a monotropic behavior, and C10-C16 had an enantiotropic smectogenic liquid crystal behavior without exhibition of the nematic phase. The average thermal stability of the smectic property was 87.33 °C, and the mesophase range was 2 °C to 14 °C. The molecular structure was confirmed by analytical and spectral analysis. The properties of liquid crystals of this new series were compared with those of other known structurally similar homologous series. The transition temperatures were determined with an optical polarizing microscope equipped with a heating phase. Conclusion: The mesomorphic thermal and optical properties of the compounds have been validated by DSC and POM techniques. The result shows that the length of the alkyl chain has a significant influence on the mesomorphic characteristics and thermal stability of the different mesophases. Evaluation of the compounds studied indicates that the molecules are sensitive to their lateral substituent, which influences the thermal characteristics and stability of the mesophase.

Novel liquid crystalline fluorene and fluorenone MIDA boronates: influence of alkyl vs alkoxy side chains on the mesomorphic properties

ABSTRACT To obtain novel boron liquid crystals, we successfully combined MIDA boronates with chromophoric fluorene and fluorenone mesogenic units and studied the influence of alkoxy versus alkyl side chains by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD). The fluorenes showed broader temperature ranges of the SmA phase compared to their fluorenone counterparts. By replacing the alkoxy side chains with alkyl side chains, the mesophase ranges could be significantly enlarged and the thermal stability increased.

Ionic strength and phase systems influence nanotubular material functionality

We synthesized novel thiacyanine chromonic liquid crystals (CLCs) and structurally characterized using NMR and mass spectrometry. The impact of distinct substitution at the para position of aromatic counter anions, aliphatic counter ion chain length, and varied spacer parity of thiacyanine dyes on CLC formation is investigated. Liquid crystal properties of the synthesized dyes are characterized by polarizing optical microscopy (POM) and X-ray diffraction (XRD) studies. Dyes exhibit nematic (N), lamellar (Lα), columnar rectangular (Colr), and columnar oblique (Colob) CLCs at different concentrations in the water. Electronic absorption spectra reveal Scheibe aggregation in all the dyes. Cylicvoltametry studies confirm redox behaviour in TC-1a and TC-5e dyes. Chromonic LCs hybrid nano-materials are synthesized using sol–gel method. Scanning electron microscopy employed to confirm nano tubular fiber structure of the hybrid nanomaterilals..

Characterization, Analysis, and Investigation of the Provenance of the Stone Construction Materials of the Vera Cruz Church (Segovia, Spain)

As part of the restoration project of the 13th century Vera Cruz Church (Segovia, Spain), a preliminary study of the stones used in its construction—dolostones of the Montejo de la Vega Fm of Santonian age (Upper Cretaceous)—and the possible location of the quarry of the provenance of these stones was carried out. For this purpose, a comparative analysis was performed between the currently active quarry of La Vera Cruz n° 88 and the historical quarry of Zamarramala. The samples were characterized using a multidisciplinary approach, combining X-ray diffraction (XRD), polarized optical microscopy (POM), and scanning electron microscopy with microanalysis (SEM-EDX). The combined mineralogical, chemical, and textural characterization provided valuable information on historical provenance. The results show a significant correlation between the dolostone samples obtained from the church and both quarries. The integral characterization confirms the suitability of the dolostones identified in the currently active quarry, Vera Cruz n° 88, for the restoration of the Vera Cruz Church, ensuring the use of appropriate materials. This study contributes to the restoration efforts of the Vera Cruz Church by providing a deeper understanding of the historical origins of the building stones.

Experimental Investigations on Highly Conducting Solid Bio‐Polymer Electrolytes Based on Latex of Calotropis gigantea Plant

AbstractThe study has prepared highly conducting polymer electrolyte films using solution cast technique with poly(vinylidene fluoride‐co‐hexafluoropropylene) PVDF‐HFP, mixture of ethylene carbonate (EC), and propylene carbonate (PC) as plasticizer and latex of Calotropis gigantea (CGL) as an ionic source. In this study, four films are prepared using PVDF‐HFP:CGL in ratio 1:1 with the increasing concentration of EC+PC as 1, 2, 3, and 4 M named as 1:1:1, 1:1:2, 1:1:3, 1:1:4. The prepared polymer electrolyte is examined by polarized optical microscopy (POM), elemental dispersive X‐ray technique (EDX), and complex impedance spectroscopy. EDX and POM are studied for the surface morphology of all prepared samples and to investigate the porous nature of films. The enhancement in ionic conductivity occurs due to CGL and increasing amount of EC‐PC. Conductivity of highest composition (1:1:4) polymer electrolyte film is found to be ≈10−3 S cm−1. The optimized polymer electrolyte film is considered as a promising candidate for application in supercapacitors.

Poly(Vinylidene Fluoride‐CO‐Hexafluoropropylene) (PVDF‐HFP) Incorporated Acetylene Black: Electrical, Optical, and Structural Studies

AbstractThe primary goal of this study is to synthesize a high‐conducting polymer electrolyte film. The PVDF‐HFP and NaSCN film are prepared which showed the highest conductivity at 30 wt% dopant of NaSCN in the Polymer PVDF‐HFP which is 1.24× 10−4 S cm−1. Therefore, here the base polymer is taken as PVDF‐HFP and NaSCN (30 wt%) and further Acetylene Black is added to check the variation in the conductivity of the polymer film. Solution casting technique is used to create solid polymer electrolyte films using poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) with salt sodium thiocyanate and Acetylene Black. Polarized optical microscopy (POM) is used to evaluate the morphology of the polymer film surface. Fourier transform infrared spectroscopy (FTIR) to check the presence of functional group is used, impedance spectroscopy is used for the measurement of the conductivity of the sample, linear sweep voltammetry for finding electrical stability window, and transference number measurements for concentration of charge carriers are done for the electrical studies of polymeric films. The 1 wt% Acetylene Black doped polymer electrolyte film is found to have the maximum ionic conductivity, which is 1.95 × 10−3 S cm−1. The solid polymer electrolyte film has an electrochemical stability window (ESW) of 4.8 V and tion value of 0.83.

Influence of Carbon Black on Conductivity and Structure of Polyethylene Oxide Based Polymer Electrolyte Film

AbstractThe potential applications of carbon black are expected to grow as science and technology improve offering up new possibilities for innovation throughout disciplines included in the field of energy storage. The present work shows the influence of carbon black to improve the ionic conductivity of the polymer electrolyte. The synthesis of polyethylene oxide: ammonium iodide based polymer electrolyte incorporated with carbon black varying from 0.01 to 0.06 wt% with respect to PEO: NH4I system by solution casting method. Different characterizations like polarized optical microscopy (POM), impedance spectroscopy, and ionic transference number (tion) are studied in detail. The maximum ionic conductivity is achieved at 0.05 wt% carbon black shows 1.20 × 10−5 S cm−1 at ambient temperature. In accordance with POM data, the amorphous region has increased whereas the crystalline region has shrunk which further indicated the increase in ionic conductivity. The value of (tion) is calculated to be 0.97 which shows the system is ionic in nature. PEO based polymer electrolyte doped carbon black can be used for the fabrication of energy storage devices.

Electrical and Structural Properties of Poly (Methyl Methacrylate) Doped Potassium Iodide (KI) Solid Polymer Electrolyte

AbstractA high‐conducting salt‐doped polymer electrolyte layer has been created here for use in photocell technologies. The solution casting method is used to produce ion conducting film where poly (methyl methacrylate) (PMMA) is used as the host polymer and potassium iodide (KI) as the dopant. The conductivity and amorphic increases of the polymer electrolytes with the addition of salt concentrations helps in the enhancement of the charge transfer properties. Using electrochemical impedance spectroscopy (EIS), ionic conductivity is evaluated where maximum conductivity is 3.99 × 10−6 S cm‐1 at 20 wt% KI concentration. Polarized optical microscopy (POM) shows the reduction in crystallinity by salt doping, while Fourier transforms infrared spectroscopy (FTIR) shows the complexation as well as composite nature of the film. Ionic transference number (tion) measurement shows the predominantly ionic nature of this polymer electrolyte.

Current Scenario and Future Prospective of Ionic‐Liquid Doped Polymer Electrolyte for Energy Application

AbstractSolid polymer electrolyte (SPE) films based on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF–HFP) with salt and ionic‐liquid (IL) are synthesized using the solution‐cast technique and summarized in this review. Doping ILs or salts increases ionic conductivity up to the device level. This is further confirmed using differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) measurements. Polarized optical microscopy (POM) affirms that enhancement in ionic conductivity is due to increase in amorphous nature of film. The complex nature of polymer electrolyte films is confirmed using Fourier transform infrared (FT‐IR) spectroscopy. Overall results show that doping IL into polyether matrix is advantageous material playing a dominant role in electrochemical devices.

Ion Conducting Polyethylene Oxide‐Based Polymer Electrolyte Dopped with Ionic Liquid‐Trifluoromethanesulfonic Chloride

AbstractIn last few decades, polymer electrolyte is the most promising candidate for the fabrication of electrochemical devices. In current work, the influence of adding the room‐temperature ionic liquid (trifluoromethanesulfonic chloride – CClF3O2S) in polyethylene oxide (PEO): ammonium iodide (NH4I) polymer electrolyte has been studied. The IL‐doped polymer electrolyte films are synthesized by solution casting method with varying stoichiometric ratios. Several experimental techniques including optical polarizing microscope, impedance spectroscopy, X‐ray diffraction, Linear sweep voltammetry, Ionic transference number thermal analysis, and electrical conductivity measurements at room temperature have been studied in detail. The complex material's maximum conductivity has been determined to be 3.3 × 10−5 S cm−1 at room temperature. The POM images show the increase in amorphous region which further confirm the improvement in ionic conductivity. Ionic transference number 0.96 shows the system is purely ionic in nature. The ESW of the IL doped polymer electrolyte is also sawed to be 3.32 V which is suitable for the fabrication of electrochemical devices.

Exploring the potential of drill cuttings for reservoir characterization: A case study from the Volga-Ural basin, Russia

The research objectives are to assess the possibility of using drill cutting analysis to obtain information about the mineralogical and geochemical properties of the reservoir rocks. Drill cutting samples were collected from a vertical well that penetrated the Domanik sediments (Semiluksk Formation) in one of the oil fields in the Volga-Ural petroleum province. Thin sections from drill cuttings were examined using an optical polarizing microscope (Axio Imager A2). X-ray diffraction (XRD) analyses were performed using a Brucker D2 Phaser X-ray powder diffractometer. Thermophysical properties were studied using an STA 449 F3 Jupiter instrument. The pyrolytic studies were performed using the Rock-Eval method. Visual inspection showed that the studied sediments are alternations of carbonates and siliceous-carbonate rocks. Thin section examinations revealed that the carbonates are mainly limestone (mudstone and wackestone) and are characterized by a dense texture and up to 30 % organic residues. The siliceous-carbonate rocks are dominated by siliceous mudstones and are characterized by dark colours, layered structure, and an enrichment in organic matter. XRD analyses showed that the carbonate rocks are mainly composed of calcite, dolomite, quartz, feldspar, and mica, which are minor components. The siliceous-carbonate rocks are dominated by quartz, followed by calcite, although they also contain feldspars, mica, dolomite, and pyrite as impurities. According to the simultaneous thermal analysis, the average total hydrocarbon in the carbonate and siliceous-carbonate rocks is 13.6 % (for the core samples) and 11.5 % (for the drill cutting samples). The content of heavy hydrocarbons in the rocks is higher than the content of light hydrocarbons, indicating the immature nature of organic matter. Kerogen is found sporadically in siliceous-carbonate rocks. According to the pyrolytic studies, average S1 is 4.4 mg/g and average S2 is 19.8 mg/g (for the core samples); average S1 is 2.1 mg/g and average S2 is 17.8 mg/g (for the drill cutting samples), which indicated that the studied sediments have very good to excellent generation potential. The average Tmax of 425.7 °C (for the drill cutting samples) and 427.9 °C (for the core samples) indicate immature organic matter that generated only heavy oils. Comparing the results of the analysed drill cutting samples with the results of the analysed core analysis from the same reservoir interval in the neighbouring wells showed a good correlation, which proves that this technique is a valid tool that provides an alternative, cost-effective method to determine the rock's characteristics from drill cuttings.

Influence of the length of end-group double bond substituents on the temperature change of phase transition in liquid crystals

ABSTRACT A series of nematic liquid crystal (LC) monomers, containing a reactive group in the lateral substituent, were designed and synthesised through an organic synthesis reaction. Considerable changes were made to the properties of the liquid monomers by varying the terminal alkyl chain lengths. The molecular structures of the intermediates and the LC monomers were characterised by flourier infrared absorption spectrometry and proton nuclear magnetic resonance (1H NMR) spectroscopy, leading to the identification of the target product. The phase transition temperatures of the LC monomers were observed and analysed using differential scanning calorimetry (DSC) and polarising optical microscopy (POM) with a hot stage. The two-way thermotropic liquid crystalline behaviour was observed during the heating process, providing insight into the effect of substituent changes on the phase transition temperature.

Visualization of structural domains in a single crystal of iron pnictide EuFe<sub>2</sub>As<sub>2</sub>

It is known that during the synthesis of superconducting EuRbFe4As4 single crystals, inclusions of its parent EuFe2As2 phase are encountered. The kinetics of the formation of the orthorhombic phase in EuRbFe4As4 crystals containing a large fraction of the EuFe2As2 phase has been studied using polarization optical microscopy. It is shown that the orthorhombic phase grows into the tetragonal one in stripes with the same crystallographic orientation, forming macro-domains. Then these domains abruptly penetrate parallel stripes of the orthorhombic phase of the second orientation, and a twin system of orthorhombic domains is formed. The process is accompanied by the appearance of macrostresses: stretching and compression waves with a characteristic period of 100–300 μm along and across the twin system, leading to spatial modulation of magnetic permeability. It has been found that even weak magnetic fields (up to 100 Oe) significantly affect the spatial distribution of the twin structure and have an effect similar to external stresses.

The influence of cholesteric helical ordering on the dynamics of liquid crystal microdroplet coalescence

ABSTRACT The dynamics of liquid crystal droplet coalescence in an isotropic melt was studied using polarised optical microscopy. Droplets of both nematic and cholesteric phases, formed from a mixture of nematic liquid crystal and chiral-photochromic dopant, were investigated. It was found that the characteristic coalescence times were significantly increased in the cholesteric phase compared to the nematic phase due to the presence of cholesteric helical ordering. In addition, these characteristic times increased as the cholesteric pitch decreased.

Cinnamic acid and biphenyl core calamitic asymmetric molecules: preparation and characterization for mesomorphic properties

ABSTRACT Some cinnamic acid and biphenyl core-derived calamitic molecules were synthesized and characterized for mesomorphic properties. Newly synthesized compounds showed well-defined schlieren textures and mosaic textures for the nematic phase and a relatively well-organized smectic A phase with focal conic textures. The chemical structures were confirmed by FT-IR, 1H-NMR, 13C-NMR and elemental analysis. The thermotropic behavior, optical textures and thermal stability have been investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), X-ray diffraction (SAXS) and thermal gravimetric analysis (TGA) respectively.

An efficient β-nucleating agent with high lattice matching rate for plate-like crystallization of polypropylene random copolymer.

It is challenging to naturally produce large amounts of β-crystals by directly adding a commercial β-nucleating agent (β-NA) into polypropylene random copolymer (PPR) at present. In this work, a novel rare earth β-NA WBN-28 was directly introduced into PPR to prepare β-PPR with high β-crystal conversion. The results of differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) indicated that it is an efficient β-NA for PPR. The β-conversion rate (β-CR) could surpass 85% when the nucleating agent content was mere 0.05%. With the further increment of nucleating agent, the β-CR increased gradually, which could reach 89.5% and 86.9% respectively calculated by DSC and WAXD when the addition amount was 0.4%. The incredible high β-CR delayed the βα-recrystallization in isothermal crystallization. The fusion peak of α-crystal was unobserved below the isothermal crystallization temperature of 122 °C when the addition amount was more than 0.2%. Furthermore, there was a highly ordered structure in WBN-28 with the periodicity of 12.89 Å, which was approximately twice of the unit cell parameter in the c direction of β-PP, indicating a high lattice matching rate between them. Intuitively observed by polarizing optical microscope (POM), the crystal grains of the blends with β-NA were more refined and finally crystallized in a plate-like shape. The forming process of the plate-like β crystalline regions were proposed by scanning electron microscope (SEM) and POM.

NANO-DOPING EFFECT ON THE PROPERTIES OF LIQUID CRYSTALS BY USING COMPUTATIONAL APPROACHES

This research uses computational analytical tools to study the impact of nano-dopants on the characteristics of liquid crystals. The main focus of the study is on the conformation analysis and degree of interaction between liquid crystal materials and nano-dopants. FTIR, UV visible spectroscopy, and thermal microscopic techniques are among the spectroscopic methods employed to analyze the information. Furthermore, computationally driven approaches are used to gain a deeper understanding of how nano-dopants influence the characteristics of materials. The molecular interactions between the various functional groups of pure and nanocomposite materials can be investigated by utilizing the wavelet transform on FTIR spectrum data. Additionally, the presence and influence of nano-dopants on liquid crystals are investigated through polarized optical microscopy (POM) and correlation studies of optical texture analysis with UV visible spectroscopy. Here, p, n-alkoxybenzoic acid (nOBA, where n = 7,9) doped with magnetic nanoparticles (Fe3O4) of size 20nm is considered for investigation. The findings from this study show the successful utilization of computational methods to analyze the effect of nano-dopants on the characteristics of liquid crystals and their potential use in the development of biosensor devices.