Nonpolar Materials Research Articles

Incorporation of nano lignin reverse micelles on the transparency, UV-blocking and rheological properties of high-density polyethylene films

Abstract Aiming to improve the poor miscibility between lignin and non-polar materials, alkali lignin (AL) was self-assembled into lignin reverse micelles (LRM) and blended with high-density polyethylene (HDPE) to fabricate composite films. The particle size of AL increased from 3.5 nm to 130 nm after forming LRM, showing a uniform spherical morphology. The water droplet contact angle increased from 54° to 89°. Optimal and rheological analysis revealed that composite films exhibited good transparency, ultraviolet (UV)-blocking performance and low viscoelasticity after adding the nano LRM. Under the optimal dosage of 5 wt% LRM, the composite film can screen 93% UV rays, and the apparent viscosities, complex viscosities, storage and loss modulus of the mixture were the lowest. Atomic force microscopy (AFM) was used to investigate the molecular interactions between lignin and HDPE. The average adhesion force between LRM and HDPE in dry air was 1.07 mN m−1, while that between AL and HDPE was 0.77 mN m−1. AFM experiments fundamentally demonstrated better compatibility between LRM and HDPE, which was beneficial for the improvement of UV-blocking, rheological properties, as well as their processability of LRM/HDPE films.

Polarity of domain boundaries in nonpolar materials derived from order parameter and layer group symmetry

Domain boundaries and other twin boundaries in crystalline materials are receiving increasing interest. They can carry unique functional properties, which in many cases are absent in the surrounding bulk material. One such property of domain boundaries can be their electric polarity. Phenomenological insight in the polarity of domain boundaries was so far based either on the knowledge of the order parameter and the form of Landau-Ginzburg free energy functional, or on the knowledge of the symmetry of the domain boundaries. In the present work we show on the concrete examples of potassium thiocyanate (KSCN) and lacunar spinel crystals, that the concept of the primary order-parameter can help to find the layer group describing the maximal possible symmetry of a given domain boundary. Combination of layer group and order parameter symmetries is then employed to clarify the nature of the polarity of domain boundaries.

Assessment of headspace solid-phase microextraction (HS-SPME) for control of asymmetric bioreduction of ketones by Alternaria alternata

The aim of this study was to assess the effectiveness of headspace solid-phase microextraction (HS-SPME) compared to liquid–liquid extractions using with methylene chloride (CH2Cl2) for control of fungal biotransformation of ketones of varying volatility. The proposed method was successfully applied. The best way to extract all the components of the mixture (alcohols, aldehydes) in quantities similar to the extraction of methylene chloride was the use of fibres coated with a combination of nonpolar material. SPME fibre assembly polydimethylsiloxane/divinylbenzene (PDMS/DVB) was most suitable for the extraction of the products mixture obtained after biotransformation of acetylcyclohexane and acetophenone. On the other hand, the best results were obtained for 2-acetylthiophene, α,α,α-trifluoroacetophenone and their derivatives using divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibre. In addition, our study showed that Alternaria alternata is a good biocatalyst for bioreduction of ketones to alcohols according to Prelog's rule.

Scaling sorbent materials for real oil-sorbing applications and environmental disasters

ABSTRACTThere are few feasible options for sorbents, which can be quickly manufactured and deployed in the event of a major oil spill and so every oil spill is an ecological disaster. This paper aims to provide an understanding of what a realistic, full-scale crude oil spill solution would look like based on the performance of the best sorbents currently available, their costs, and their advantages.Adsorbent materials or “sorbents” described here have been a recent target for research toward applications in environmental cleanup, remediation, and hazardous material containment. These materials contain many compositions, syntheses, and practical manufacturing parameters that make most of them practically and logistically unfit to tackle quantities much larger than a single barrel of oil. Different properties of crude oil and nonpolar materials, such as their viscosity, density, and weathering, can also make these materials seem attractive on a lab scale but underperform in field testing and in practical applications. This review addresses the challenges, advantages, and disadvantages of different technical applications of the superior sorbent materials and material types in the literature. In addition, we discuss the different costs and manufacturing challenges of sorbent materials in real oil spills and what a feasible containment sorbent material might look like.

Large tetragonality and room temperature ferroelectricity in compressively strained CaTiO3 thin films

Ferroelectricity and piezoelectricity are desirable for a variety of high-temperature applications such as actuators and sensors in heat engines, high-temperature manufacturing, and space technologies; however, the material candidates are currently limited. Here, we demonstrate that CaTiO3, the prototype perovskite mineral, abundantly found in the Earth, which as a nonpolar material in bulk form, becomes a high-temperature ferroelectric oxide under compressive strain when grown as a thin film. A strain-phase-temperature diagram of CaTiO3 films is created by growing films on various substrates with different in plane strains in order to map out the polar behavior for compressive and tensile strain. Using temperature dependent optical second harmonic generation analysis, we show that tensile strained films exhibit predominantly in-plane polarization with orthorhombiclike point group symmetry with a phase transition below room temperature. On the other hand, compressively strained CaTiO3 films exhibit a near-tetragonal unit cell with a c/a ratio of 1.03, larger than that of classic ferroelectric, e.g., BaTiO3 (c/a ∼ 1.01). These films exhibit a robust and switchable out-of-plane polarization at room temperature, with a ferroelectric transition temperature up to ∼800 K. Density functional theory calculations reveal that compressive strain gives rise to a large out-of-plane displacement of Ti-cations inside the TiO6 octahedral cages and is the major contributor to the calculated polarization of ∼9 µC/cm2. Given that nearly half of the perovskites exhibit the bulk symmetry of CaTiO3, compressive strain tuning of this perovskite family may prove to be a fertile ground for the discovery of strain-induced piezoelectrics and ferroelectrics at high-temperatures.

Investigations into sampling approaches for chemical analysis of latent fingermark residue

The quantitative variation in latent fingermark deposits sampled from the same donor (intra-donor) poses considerable challenges to studies into the chemical composition of latent fingermarks. The work presented here investigates approaches to the sampling of latent fingermark residues within this context. The amount of squalene in fingermarks deposited on non-porous surfaces, determined by GC–MS, was used as an indicator of the amount of non-polar material present. It was found that the percentage difference of squalene between deposits from two hands at a given time, without controlling the deposition force, was in the range of 4–100%. This was reduced to 0–44% in alternative sampling approaches where deposition force was controlled. These results demonstrate the significant influence of sampling on subsequent chemical analysis of fingermark residues, and offer possible sampling strategies to overcome issues associated with intra-donor variation.

Conductive CoOOH as Carbon‐Free Sulfur Immobilizer to Fabricate Sulfur‐Based Composite for Lithium–Sulfur Battery

AbstractLithium–sulfur battery is recognized as one of the most promising energy storage devices, while the application and commercialization are severely hindered by both the practical gravimetric and volumetric energy densities due to the low sulfur content and tap density with lightweight and nonpolar porous carbon materials as sulfur host. Herein, for the first time, conductive CoOOH sheets are introduced as carbon‐free sulfur immobilizer to fabricate sulfur‐based composite as cathode for lithium–sulfur battery. CoOOH sheet is not only a good sulfur‐loading matrix with high electron conductivity, but also exhibits outstanding electrocatalytic activity for the conversion of soluble lithium polysulfide. With an ultrahigh sulfur content of 91.8 wt% and a tap density of 1.26 g cm−3, the sulfur/CoOOH composite delivers high gravimetric capacity and volumetric capacity of 1199.4 mAh g−1‐composite and 1511.3 mAh cm−3 at 0.1C rate, respectively. Meanwhile, the sulfur‐based composite presents satisfactory cycle stability with a slow capacity decay rate of 0.09% per cycle within 500 cycles at 1C rate, thanks to the strong interaction between CoOOH and soluble polysulfides. This work provides a new strategy to realize the combination of gravimetric energy density, volumetric energy density, and good electrochemical performance of lithium–sulfur battery.

SYNTHESIS AND CHARACTERIZATION OF A PERIODIC MESOPOROUS ORGANOSILICA MOLECULAR IMPRINTED POLYMER FOR REMOVAL OF DDT

A Periodic Mesoporous Organosilica (PMO) is an organic-inorganic hybrid composition with ordered porous structure on a molecular imprinted polymer (MIP). A triblock copolymer Pluronic F127 poly(ethyle ne glycol)- poly(propylene glycol)-poly(ethylene glycol) as structure directing agent (SDA) and 1,4-bis(triethoxysilyl)benzene (BTEB) as a precursor were used to synthesis the PMO-MIP using a non-covalent approach. The non-covalent approachshowed a limited number of selective imprinted sites due to the lack of strong intermolecular attractions between DDT template and the BTEB precursor. However, treatment of PMO-MIP with chlorotrimethylsilane (CTMS) significantly reduced the SiO-H and Si-OH resulting in a more non-polar material. The synthesized PMO-MIP was able to recover 106%, 85% and 99% of DDT, DDD and DDE respectively which shows that it can be used not only for extraction of DDT and its metabolites from environmental samples but also as a clean-up for samples.

NiCo2O4 Nanofibers as Carbon‐Free Sulfur Immobilizer to Fabricate Sulfur‐Based Composite with High Volumetric Capacity for Lithium–Sulfur Battery

AbstractBoth the energy density and cycle stability are still challenges for lithium–sulfur (Li–S) batteries in future practical applications. Usually, light‐weight and nonpolar carbon materials are used as the hosts of sulfur, however they struggle on the cycle stability and undermine the volumetric energy density of Li–S batteries. Here, heavy NiCo2O4 nanofibers as carbon‐free sulfur immobilizers are introduced to fabricate sulfur‐based composites. NiCo2O4 can accelerate the catalytic conversion kinetics of soluble intermediate polysulfides by strong chemical interaction, leading to a good cycle stability of sulfur cathodes. Specifically, the S/NiCo2O4 composite presents a high gravimetric capacity of 1125 mAh g−1 at 0.1 C rate with the composite as active material, and a low fading rate of 0.039% per cycle over 1500 cycles at 1 C rate. In particular, the S/NiCo2O4 composite with the high tap density of 1.66 g cm−3 delivers large volumetric capacity of 1867 mAh cm−3, almost twice that of the conventional S/carbon composites.

Roll-to-roll electrochemical fabrication of non-polarizable silver/silver chloride-coated nylon yarn for biological signal monitoring

The main goal of this work is to develop a fabrication process and system for silver/silver chloride (Ag/AgCl)-coated yarn, as Ag/AgCl is the preferred non-polarizing material for interfacing with the body in a clinical setting when monitoring biological signals. A roll-to-roll electrochemical system was designed and built to deposit AgCl on Ag-coated nylon 6,6 yarn in a controllable process. In particular, the movement of the yarn, voltage limit and mixing of 0.9% sodium chloride solution were held constant while the applied current was varied. The Ag-coated nylon acted as the working electrode with two counter electrodes made of platinum. The optimal Ag/AgCl yarns were then further characterized. The roll-to-roll parameters identified include the applied current of approximately 1.82 mA/cm2 for the Ag-coated nylon yarn with a voltage limit of 2.00 V while in the electrochemical chamber. In addition, the yarn had a uniform movement of 0.08 cm/s, which meant that 7 cm of yarn was in the chamber for approximately 89.17 s. The fabrication process was relatively repeatable, yielding the average resistance of 11.0 ± 1.8 Ω/cm for the optimal Ag/AgCl-coated yarn with a low standard deviation between different fabrication processes. A proof-of-concept system was developed and parameters important for the fabrication of functional Ag/AgCl electronic textiles (e-textiles) were detailed. An effective roll-to-roll fabrication method for Ag/AgCl-coated yarns has the potential to significantly contribute to the design and development of wearable e-textile biological monitoring systems that require Ag/AgCl sensor materials.

Observations of Partial Discharge Echo in Dielectric Void by Applying a Voltage Chopped Sequence

This paper describes a novel observation on partial discharges (PDs), which occur despite the absence of an applied voltage, within a chopped sequence. It was found that additional discharge pulses occur when a specimen is subjected to chopped sequences rather than a continuous sinusoid. The discharge pulses, called Partial Discharge Echoes (PDE), appeared in time intervals (where no voltage was being applied), immediately after the specimen had been exposed to a base waveform (e.g., sinusoidal) above a partial discharge inception level. The chopped timing is composed of a multiple series of packets consisting of base waveforms, with each packet being separated in time by a defined delay period. The presented experiments were performed on specimens with an embedded gaseous void, in thermosetting insulation and glass as a non-polar material, for comparison. Acquisition of the echo signal was performed in the phase-resolved mode, modifying the synchronization path and the settings. In contrast to continuous sinusoidal PD measurements, the chopped approach might provide a deeper insight into key PD phenomena, such as inception, propagation, time lag, post-discharge time decay, and effective surface area. Special focus was paid to the transition point between sinusoidal phase and the echo interval. The various scenarios of an echo mechanism, depending on the coincidence of remnant polarization field and the field accumulated on void walls, are discussed.

Energy loss rate of hot electrons due to polar-optical phonon modes in a semiconductor nanowire under transverse electric field

Within the frame of electron-temperature model we calculate the average energy loss rate due to interface and confined longitudinal optical (LO) phonon emission from a hot-electron gas to a cold lattice in polar semiconductor nanowire surrounded by non-polar material. The system both with and without hot-phonon effect is investigated. The impact of a perpendicular electric field on average energy loss rate is explored. The energy loss rate dependences on electric field strength, wire radius and electron temperature are obtained. It has been shown that the energy loss rate is more sensitive to the electric field when the wire radius is larger. The presented results indicate that the electric field applied perpendicularly to the wire axis can serve as a means to control the energy loss rate. There is an experimental evidence concerning to the increase of energy loss rate with increasing electron temperature as we have obtained.

Extended depth of field in continuous-wave terahertz computed tomography based on Bessel beam

Terahertz (THz) radiation is able to penetrate many different types of nonpolar and nonmetallic materials. THz imaging can be combined with computed tomography (CT) to form THz CT, which is an effective method to visualize the sample’s internal structure. Here, we report the continuous-wave (CW) THz CT imaging results using Bessel beam generated by use of axicon. In this method, the sample cross section is scanned in all translation and rotation directions. Due to the non-diffracting property of the Bessel beam, two-dimensional (2-D) cross-sectional images of the internal structure of the plastic pipe at different distances from axicon can be full reconstructed by using filtered back projection algorithm. Compared with conventional Gaussian beam, Bessel beam can extend the depth of field in CW THz CT system. Using this system, we obtained 2-D cross-sectional image of the internal structure of the clogged plastic pipe and the obstruction was accurately detected by comparing 2-D cross-sectional images at different sections. Our experimental data demonstrated a feasible application of the CW THz CT system with Bessel beam in non-destructive testing.

Syntheses of Diverse Donor-Substituted Bisbenzofuro[2,3- b:3',2'- e]pyridines (BBZFPys) via Pd Catalysis, and Their Photophysical Properties.

A series of bisbenzofuro[2,3- b:3',2'- e]pyridines (BBZFPys) bearing a chlorine functionality have been efficiently synthesized through a Pd-catalyzed double oxidative intramolecular C-H/C-H coupling of monochlorinated 2,6-diaryloxypyridines. The subsequent Buchwald-Hartwig amination of the chlorinated BBZFPys allowed for the access to a new class of donor-acceptor (D-A) π-conjugated compounds that comprise BBZFPy as an electron acceptor (A) and diarylamines as a donor (D) unit. The investigation of the steady-state photophysical properties of the prepared D-A compounds revealed that they are emissive in both solution and solid states in the blue-to-green color region. The singlet-triplet energy splitting (Δ EST) was found to be much smaller than that of substituent-free BBZFPy (0.70 eV), ranging from 0.01 to 0.56 eV. The time-resolved spectroscopy revealed that the D-A compounds, comprising a bis( tert-butyl)carbazole as the D and CF3-attached BBZFPy as the A, showed delayed fluorescence (DF) in nonpolar matrix host material (Zeonex), while in a polar matrix (DPEPO), room-temperature phosphorescence (RTP) was faintly observed. Furthermore, organic light-emitting diodes (OLEDs) fabricated with the D-A compounds as a blue emitter showed a moderate external quantum efficiencies (EQEs) up to 1.5%.

The collective behavior of shear strain localizations in dipolar materials

We study the collective behavior of shear bands in HY-100 steel and OFHC copper taking into account the dipolar effects. Starting from mathematical model, we present new numerical methodology that allows one to simulate the processes of shear strain localization in nonpolar and dipolar materials. The verification procedure was performed to prove the efficiency and accuracy of the proposed method. Using the proposed algorithm we investigate the statistical characteristics of the shear strain localization processes in dipolar materials and compare results with nonpolar case. In particular, we obtain the statistical distributions of the width of localization zones and distance between them.

An effective polysulfides bridgebuilder to enable long-life lithium-sulfur flow batteries

Polysulfides shuttle, although is not the only one, but definitely the most prominent problem which hinders the commercialization of lithium-sulfur cells. Herein, a functionally designed SiO2 tethered 1-methyl-1-propylpiperidinium chloride (SiO2-PPCl) ionic liquid nanoparticle is adopted as a bridgebuilder between the carbon carrier and lithium polysulfides (LPS) to modulate shuttle issues. The SiO2-PPCl exerts effective adhesion to both polar LPS and nonpolar carbon carrier material by its special function groups, which make it act as a bridge between them, therefore, the dissolved LPS are prevented from migrating to lithium anode effectively, and the corresponding LPS shuttle is controllable by simply tuning the ratio of SiO2-PPCl to sulfur. This strategy is demonstrated in a lithium sulfur suspension flow cell in which the shuttle effect is more serious because large quantity of electrolyte is adopted, and over 1000 cycles is achieved with high coulombic efficiency of 99%. Verified in a laboratory flow cell equipment, the approach of exploiting polysulfides bridgebuilder to control LPS shuttle manifests its feasibility and offers a new direction to develop lithium-sulfur batteries.

Advances in Polar Materials for Lithium–Sulfur Batteries

AbstractLithium–sulfur batteries are regarded as promising candidates for energy storage devices due to their high theoretical energy density. Various approaches are proposed to break through the obstacles that are preventing Li–S batteries from realizing practical application. Recently, the importance of the strong chemical interaction between polar materials and polysulfides is recognized by researchers to improve the performance of Li–S batteries, especially with respect to the shuttle effect. Polar materials, unlike nonpolar materials, exhibit strong interactions with polysulfides without any modification or doping because of their intrinsic polarity, absorbing the polar polysulfides and thus suppressing the notorious shuttle effect. The recent advances on polar materials for Li–S batteries are reviewed here, especially the chemical polar–polar interaction effects toward immobilizing dissolved polysulfides, and the relationship between the intrinsic properties of the polar materials and the electrochemical performance of the Li–S batteries are discussed. Polar materials, including polar inorganics in the cathode and polar organics as binder for the Li–S batteries are respectively described. Finally, future directions and prospects for the polar materials used in Li–S batteries are also proposed.

The relationship between covalent bonds and the optical response in a nonpolar family ATeMoO6 (A=Mg, Zn, Cd): A Berry-phase investigation

The macroscopic polarization, the refractive indices, birefringence, and the second-order nonlinear optical susceptibilities in a family of nonpolar materials ATeMoO6 (A = Mg, Zn, and Cd) have been investigated using the Berry-phase calculation. The microscopic origin of the optical response is further investigated by the variation of atomic charge, the Born effective charges, and the chemical bond analyses based on the Bader charge analysis and the Mulliken bond population analysis. The results show that the robust covalent bonds play an important role in determining the refractive indices and SHG response, and the anisotropic electron distributions on covalent Te‒O and Mo‒O bond give main contribution to the optical anisotropic birefringence.

Effect of the direct injection plasma (DIP) treatment on the bonding strength of adhesive bonded joints

The adhesive bonding of thermoplastic materials requires, attributable to the low surface energy, a surface activation. The atmospheric pressure (AP) plasma treatment is a common method to improve the surface characteristics. An entirely new process type is the direct injection plasma (DIP) treatment, which combines the injection molding and the surface activation to a full-inline process. During the cooling phase of the injection molding cycle, a pre-defined area of the molded part can be activated by sending a plasma afterglow through a channel. In preliminary publications, it could be shown that the surface activation leads, dependent on the process parameters, to high surface energies up to a treatment length of more than 500 mm. The aim of the current investigations was to examine the influence factors for high bonding strengths after surface activation. Therefore, in this work, the bonding strengths of DIP-treated surfaces were investigated and compared with the surface energy and the XPS-spectrum along with the treatment length. Based on the DIN standard 1465, the lap shear test method was used to measure the bond strength, which, caused by the application-related test specimen, had to be adjusted for the investigations. Furthermore, for the investigation, two different substrate materials and adhesives were used. With PP, a nonpolar material and, with PA6, a polar material for the substrates were used. As adhesive systems, a polyurethane (PUR) and an epoxy resin system were used, both as multi-component adhesives.

Application of continuous-wave terahertz computed tomography for the analysis of chicken bone structure

Terahertz (THz) radiation is able to penetrate many different types of nonpolar and nonmetallic materials without the damaging effects of x-rays. THz technology can be combined with computed tomography (CT) to form THz CT, which is an effective imaging method that is used to visualize the internal structure of a three-dimensional sample as cross-sectional images. Here, we reported an application of THz as the radiation source in CT imaging by replacing the x-rays. In this method, the sample cross section is scanned in all translation and rotation directions. Then, the projection data are reconstructed using a tomographic reconstruction algorithm. Two-dimensional (2-D) cross-sectional images of the chicken ulna were obtained through the continuous-wave (CW) THz CT system. Given by the difference of the THz absorption of different substances, the compact bone and spongy bone inside the chicken ulna are structurally distinguishable in the 2-D cross-sectional images. Using the filtered back projection algorithm, we reconstructed the projection data of the chicken ulna at different projection angle intervals and found that the artifacts and noise in the images are strikingly increased when the projection angle intervals become larger, reflected by the blurred boundary of the compact bone. The quality and fidelity of the 2-D cross-sectional images could be substantially improved by reducing the projection angle intervals. Our experimental data demonstrated a feasible application of the CW THz CT system in biological imaging.