Good Miscibility Research Articles

Achieving high efficiency and well-kept ductility in ternary all-polymer organic photovoltaic blends thanks to two well miscible donors

<h2>Summary</h2> All-polymer solar cells (APSCs) are one of the most promising types of application-oriented photovoltaic technologies because they are operationally and mechanically stable; however, their low power conversion efficiency (PCE) restricts the core competitiveness against other types of solar cells. Besides, poor insight of mechanical performance, such as ductility, has been revealed for cutting-edge APSCs. Herein, we chose two well miscible polymer donors, PM6 and J71, and achieved a PCE of 16.52% for APSCs in a ternary blend with PY-IT and 15.74% for air-processed devices. The improvement is enabled by effective energy transfer, tuned crystallinity, and improved phase separation, which resulted in faster charge transfer and more balanced charge transport, suppressed exciton recombination, and more efficient charge extraction. Furthermore, the good miscibility between two donors enabled the target to have well-maintained film morphology without damaging the initial nanoscale network, bringing comparable film ductility. Last, the inner structure-property relationship of photovoltaic and morphological parameters, and film ductility was illustrated by a correlation study.

Steric hindrance effect on miscibility and properties of palm oil derived pentaerythritol ester lubricants

The miscibility and solubility between refrigerant and lubricant is a prerequisite in any refrigeration system. Polyol is known to have good miscibility with refrigerant and can be synthesized from methyl ester of vegetable oils via transesterification reaction. Pentaerythritol (PE) ester is the best biolubricant in hydrofluorocarbons (HFCs) refrigerant system due to its high viscosity. PE ester was analyzed for its physicochemical properties and was compared with commercial refrigeration polyol ester (POE) RL 68H. The kinematic viscosity and density of PE ester were comparable with commercial POE. The pour point was obtained at −24 °C which is slightly higher than commercial POE. Nevertheless, the PE ester was not completely miscible in refrigerant, HFC R134a. The miscibility with refrigerant decreases as the number of ester functional group increases and the number of fatty acids carbon chain increases because of the neopentyl structure of esters hindered the ester functional group to interact with polar group of HFC refrigerant. An appropriate surfactant is needed to improve the miscibility and solubility of PE ester with HFC refrigerant.

Naphthalene diimide-based random terpolymer acceptors for constructing all-polymer solar cells with enhanced fill factors.

All-polymer solar cells (all-PSCs) with mechanical and thermal stability have potential for applications in flexible devices. Polymer acceptors based on naphthalene diimide (NDI) have been widely studied because of their strong electron affinity, high electron mobility, and high mechanical reliability. However, controlling the film morphology of the polymer–polymer blends of NDI-based all-PSCs is difficult. Consequently, all-PSCs based on NDI building blocks exhibit a low fill factor (FF) and a lower power-conversion efficiency (PCE) than state-of-the-art polymer solar cells. In this work, we added a small amount of dicyanodistyrylbenzene (DCB) unit to the NDI-based polymer acceptor N2200 through random copolymerization and synthesized a series of NDI-based terpolymer acceptors PNDIx, where x is the molar concentration of DCB units relative to NDI units. PNDI5 and PNDI10, corresponding to 5% and 10% molar concentrations of DCB, respectively, showed lower crystallization and good miscibility with PBDB-T, a widely used electron-donating copolymer, than the terpolymer based on DCB-free N2200. Moreover, compared to the PBDB-T:N2200 device, the PNDI5-based device exhibited a much higher PCE (8.01%), and an enhanced FF of 0.75 in all-PSCs. These results indicate that ternary random copolymerization is a convenient and effective strategy for optimizing the film morphology of NDI-based polymers, and that the resulting terpolymer acceptor is a promising n-type acceptor for constructing high-performance all-PSCs.

Chitosan-Polyvinyl Alcohol blend as beta-ray attenuator

Living organism exposure to radiation beyond certain limit is dangerous, while handling the radioactive materials. High Z- materials give proper shielding to this radiation, but the associated production of external bremsstrahlung, high cost of materials, hazardous nature of materials like lead (Pb) make us to choose low Z polymer as shielding material. Present work investigating on the beta attenuation properties of Chitosan-Polyvinyl Alcohol blend films. The films of individual polymers and their blends in different ratios having different thickness were prepared and attenuation study has been carried out with the help of G M Counter and Tl-204 beta active radiation source. FTIR, XRD, DSC, TGA, SEM characterisation shows that blend with 10–90(CH-PVA) and 30–70(CH-PVA) ratios have good attenuation property because of good miscibility of polymers in the blend. Miscibility of blend reduces as chitosan content increases and hence attenuation values also decreases. These results suggest the feasibility of using CH-PVA blend as low energetic beta attenuator.

High Miscibility Compatible with Ordered Molecular Packing Enables an Excellent Efficiency of 16.2% in All-Small-Molecule Organic Solar Cells.

In all-small-molecule organic solar cells (ASM-OSCs), a high short-circuit current (Jsc ) usually needs a small phase separation, while a high fill factor (FF) is generally realized in a highly ordered packing system. However, small domain and ordered packing always conflicted each other in ASM-OSCs, leading to a mutually restricted Jsc and FF. In this study, alleviation of the previous dilemma by the strategy of obtaining simultaneous good miscibility and ordered packing through modulating homo- and heteromolecular interactions is proposed. By moving the alkyl-thiolation side chains from the para- to the meta-position in the small-molecule donor, the surface tension and molecular planarity are synchronously enhanced, resulting in compatible properties of good miscibility with acceptor BTP-eC9 and strong self-assembly ability. As a result, an optimized morphology with multi-length-scale domains and highly ordered packing is realized. The device exhibits a long carrier lifetime (39.8 μs) and fast charge collection (15.5ns). A record efficiency of 16.2% with a high FF of 75.6% and a Jsc of 25.4mA cm-2 in the ASM-OSCs is obtained. These results demonstrate that the strategy of simultaneously obtaining good miscibility with high crystallinity could be an efficient photovoltaic material design principle for high-performance ASM-OSCs.

Over 18% ternary polymer solar cells enabled by a terpolymer as the third component

“Ternary blending” and “random terpolymerization” strategies have both proven effective for enhancing the performance of organic solar cells (OSCs). However, reports on the combination of the two strategies remain rare. Here, a terpolymer PM6-Si30 was constructed by inserting chlorine and alkylsilyl-substituted benzodithiophene (BDT) unit (0.3 equivalent) into the state-of-the-art polymer PM6. The terpolymer exhibitsadeep highest-occupied-molecular-orbital energy and good miscibility with both PM6 and BTP-eC9 (C9) and enables its use as a third component into PM6:PM6-Si30:C9 bulk-heterojunction for OSCs. The resulting cells exhibit maximum power conversion efficiency (PCE) of 18.27%, which is higher than that obtained for the optimized control binary PM6:C9-based OSC (17.38%). The enhanced performance of the PM6:PM6-Si30:C9 cells is attributed to improved charge transport, favorable molecular arrangement, reduced energy loss and suppressed bimolecular recombination. The work demonstrates the potential of random terpolymer as a third component in OSCs and highlights a new strategy for the construction of a ternary system with improved photovoltaic performance.

Modified cardanol based colorless, transparent, hydrophobic and anti-corrosive polyurethane coating

Despite having unique functional properties, renewable resourced cardanol based polymers have limited usage in industrial coatings because of its dark brown or red color after polymerization. The current work reports the development of colorless, transparent, hydrophobic and corrosion resistant coating derived from cardanol 2,3-dihydroxy propyl ether (CPE) and modified with hydroxy-terminated polydimethylsiloxane (HTPDMS). CPE was synthesized to be used as a reactive aliphatic diol in forming polyurethane (CPU) and characterized. HTPDMS-CPU copolymers with multifunctional properties were prepared through copolymerization of 5, 10, 15, 20 wt% HTPDMS and CPE. HTPDMS-CPU coatings showed improved adhesion and hydrophobicity (>100°), enhanced transparency with easy readability underneath and a reasonable UV transmittance (92–96%). One distinct Tg and single phase surface morphology of HTPDMS10CPU and HTPDMS15CPU confirmed the good miscibility and compatibility of the system. Electrochemical Impedance Spectra (EIS), salt water immersion and salt spray studies revealed the anti-corrosive property of the copolymers with best performance at 10–15 wt% HTPDMS content. Thermogravimetric study showed almost no interference in thermal stability after the incorporation of HTPDMS into the system. The development of HTPDMS-CPU co-polymeric multifunctional coatings represents a more effective pathway to achieve multi-functional coatings with desirable hydrophobic, anti-corrosive and improved thermal stability.

Reduced miscibility between highly compatible non-fullerene acceptor and donor enables efficient ternary organic solar cells

The morphology of the photoactive layer within organic solar cells (OSCs) plays a key role in determining device performance. In addition to the film forming conditions, miscibility between donors and acceptors critically derives the corresponding morphology, which can be empirically evaluated by the Flory–Huggins interaction (χ). Herein, a new non-fullerene acceptor (NFA) with long alkyl chains and fluorinated end groups, BTP-4F–C9-20, is reported, which has sufficient solubility in common solvents and good miscibility with the polymer donor PM6. PM6:BTP-4F–C9-20 binary OSC achieved a maximum PCE of 16.5%, as a result of fine phase separation that creates abundant heterojunctions for exciton dissociation but insufficient bi-continuous pathways for charge transport. A chlorinated NFA Y7-BO with higher χ with PM6 is introduced into the PM6:BTP-4F–C9-20 host system, which increases phase separation with slightly enlarged domains to better shape the charge transport pathways. The PM6:BTP-4F–C9-20:Y7-BO (1:1.1:0.1) ternary OSC achieved a higher PCE of 17.3%, although Y7-BO provides limited complementary light absorption. This work demonstrates that the Flory–Huggins interaction is an effective parameter to fine tune the morphology of ternary OSCs to promote photovoltaic performance.

Unraveling the Role of Neutral Units for Single-Ion Conducting Polymer Electrolytes.

With the cationic transference number close to unity, single-ion conducting polymer electrolytes (SICPEs) are recognized as an advanced electrolyte system with improved energy efficiency for battery application. The relatively low ionic conductivity for most of the SICPEs in comparison with liquid electrolytes remains the major "bottleneck" for their practical applications. Polyethylene oxide (PEO) has been recognized as a benchmark for solid polymer electrolytes due to its high salt solubility and reasonable ionic conductivity. PEO has two advantages: (i) the polar ether groups coordinate well with lithium ions (Li+) providing good dissociation from anions, and (ii) the low Tg provides fast segmental dynamics at ambient temperature and assists rapid charge transport. These properties lead to active use of PEO as neutral plasticizing units in SICPEs. Herein, we present a detailed comparison of new SICPEs copolymerized with PEO units vs SICPEs copolymerized with other types of neutral units possessing either flexible or polar structures. The presented analysis revealed that the polarity of side chains has a limited influence on ion dissociation for copolymer-type SICPEs. The Li+-ion dissociation seems to be controlled by the charge delocalization on the polymerized anion. With good miscibility between plasticizing neutral units and ionic conductive units, the ambient ionic conductivity of synthesized SICPEs is still mainly controlled by the Tg of the copolymer. This work sheds light on the dominating role of PEO in SICPE systems and provides helpful guidance for designing polymer electrolytes with new functionalities and structures. Furthermore, based on the presented results, we propose that designing polyanions with a highly delocalized charge may be another promising route for achieving sufficient lithium ionic conductivity in solvent-free SICPEs.

Study on preparation and properties of new thermosetting epoxy asphalt

Epoxy asphalt is not widely used because of its high price and miscibility problems of the epoxy resin and asphalt. Herein, a new thermosetting epoxy asphalt (NEA) was prepared with oleylamine as a curing agent. The tensile test showed that NEA has high tensile strength (4.4 MPa) and fracture strain (594%). Fourier transform infrared analysis of the NEA showed that the unsaturated double bond in oleylamine reacted with the active group in asphalt, which effectively introduced asphalt into the network structure formed by curing epoxy resin. The non-polar long chain on oleylamine awarded the NEA with excellent toughness and effective miscibility with non-polar asphalt, which can be confirmed by tensile test and fluorescence microanalysis. The temperature scanning results and the master curve obtained by dynamic shear rheometer test revealed that NEA is an excellent damping material with excellent low-frequency and high-frequency performance. The reaction mechanism of NEA was proposed based on the macro and micro analysis results. This study provided a facile approach for preparing a low-cost NEA modified asphalt by oleylamine curing agent having good miscibility with asphalt and enhanced mechanical properties, and hence can be counted as an alternative contender for applications in pavement, construction, and engineering industries.

Methane storage in clathrate hydrates containing water‐miscible oxirane promoters

As the share of natural gas in the global demand for energy continues to increase, there is a growing need for sustainable, energy-efficient, and cost-effective natural gas storage and transportation technologies. This study investigates methane hydrates (MHs) containing two oxirane compounds, namely, propylene oxide (PO) and epoxyisobutane (EIB), for their potential use in hydrate-based methane storage (HBMS) applications. The microstructures of the MHs containing both PO and EIB were identified as the sII type by high-resolution powder diffraction (HRPD), 13C NMR, and Raman spectroscopy. Moreover, the addition of PO/EIB significantly improved the thermodynamic stability of simple MH. In particular, as EIB increased the equilibrium temperature by 15 K, the EIB + CH4 hydrate remained stable up to ambient temperature (19°C) even under a mild pressure (30 bar). It was also clearly demonstrated that PO and EIB act as simple hydrate formers (SHFs) with good water miscibility. The EIB + CH4 hydrate also showed a remarkable CH4 capacity of 0.117 mol CH4/mol H2O or 117 m3 CH4 (at STP)/m3 hydrate, nearly identical to the theoretical maximum. It is believed that both PO and EIB could potentially be employed to facilitate sustainable and energy-efficient HBMS technologies owing to the combined excellence of their high promotion capability and energy density, and good water miscibility. Novelty statements Both PO and EIB act as powerful promoters with good water miscibility. Both PO and EIB act as simple sII hydrate formers. Approximately 120 m3 of methane gas can be stored in 1 m3 of EIB hydrate.

A thermadapt epoxy based on borate ester crosslinking and its carbon fiber composite as rapidly processable prepreg

Introduction of the dynamic bonds will endow the polymer architectures with attractive adaptive properties, which enable thermoset materials re-processable, recyclable and sustainable. However, exploration of the miscible and cost-effective moieties containing such dynamic fragments are the burning question to implement the reversible polymer on a mass basis. Here we report an indirect formation strategy of borate ester crosslinkage from commercially available feedstocks. Remarkably, the borate ester crosslinks are ingeniously generated from borate and diols which are formed in-situ by glycidol and amines. The good miscibility of the precursors could be achieved without the use of any solvent, which benefits the large-scale production and practical application of these promising adaptive thermoset polymers. Such thermadapt epoxy networks utilizing dynamic borate ester crosslinking exhibit adaptive properties such as reprocessing, welding, self-healing, and extrusion injection molding. In addition, the facile reprocess and remold processes of resulted carbon fiber composite are demonstrated by incorporating thermadapt epoxy resin with continuous carbon fiber sheets. Our synthetic strategy provides innovative insights as a green and sustainable solution to traditional thermosets and its composites.

Johnson Matthey, Kebotix collaborate on digital R&D engine for catalytic coatings

This paper attempts to explore the impact of the addition of 1,4-dioxane (DOX) with gasoline by volume proportion of 1.5%, 3% & 5% as a performance enhancer in the spark-ignition engine. The DOX possess two oxygen molecules in its chemical structure with good flammable characteristics, and also results in good miscibility and stability with gasoline. The endoscopic technique is employed for spatial visualization and characterization of the combustion flame on the crank angle basis. Spatial flame characteristics and temperature distributions are evaluated by processing the captured digital images. The result shows that flame initiation and propagation are advanced and faster with the addition of DOX in the gasoline respectively. The ring structure and inherent oxygen content of the DOX increased flame speed and improved the combustion characteristics. From the performance and emission analysis, it is found that brake thermal efficiency of gasoline fuel is 24.72%, which is less when compared to the brake thermal efficiency of DOX3 (gasoline 95% + DOX 5%), whose value is 25.42% at full load condition. The HC and CO emissions are decreased by about 6.8% and 10.3% for the DOX3 blend when compared to sole gasoline at full load. This is due to the presence of inherent oxygen and faster burn rate exhibited by the DOX blend which promotes fuel oxidation. NOx emission increased slightly with an increase in the DOX percentage.

Tuning the Surface Reactivity and Tribological Performance of Phosphonium-Based Ionic Liquid at Steel/Steel Interfaces by Bromide/Phosphate Anion Mixtures

Phosphonium phosphate ionic liquids (ILs) are promising lubricant additives for engine oils owing to a combination of good tribological performance and attractive properties, such as high thermal stability and good miscibility with mineral and synthetic oils. Here, we evaluate the dependence of the lubricating performance of trihexyltetradecylphosphonium ([P6,6,6,14])-based ILs when used in steel/steel contacts on the relative concentration of bis(2-ethylhexyl)phosphate ([DEHP]) and bromide (Br-) anions. The results indicate no changes in friction and wear upon increasing the [P6,6,6,14]Br-to-[P6,6,6,14][DEHP] volume ratio up to 0.2:1, while a further increase in this ratio leads to a reduction of friction and wear. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry measurements highlight that the dependence of the lubricating properties of the ILs on the [P6,6,6,14]Br-to-[P6,6,6,14][DEHP] ratio originates from the balance between corrosivity and surface reactivity of this IL: while [DEHP] acts as corrosion inhibitor in the non-contact region, the formation of species containing phosphorus-oxygen moieties in the wear track as a result of the hydrolysis of phosphonium ions increases the surface coverage of phosphorus. This is proposed to decrease friction by decreasing adhesion at steel/steel contacts and lowering the interfacial shear strength.

Preparation of Fucoidan-Based Electrospun Nanofibers and Their Interaction With Endothelial Cells.

Sulfated polysaccharide fucoidan (FD) is widely applied in biomedical applications owing to its outstanding bioactivities. In addition to the biochemical features, the architecture of biomaterials plays a critical role in tissue repair and regeneration. Particularly, nanofibers have elicited great interest due to their extracellular matrix-like structure, high specific surface area, and favorable biological properties. Herein, chitosan-modified FD/ultra-high molecular weight polyethylene oxide (UHMWPEO) nanofibers are developed via green electrospinning and electrostatic interaction for studying their interaction with endothelial cells. The appropriate solvent is screened to dissolve FD. The electrospinnability of FD/UHMWPEO aqueous solutions is greatly dependent on the weight ratios of FD/UHMWPEO. The incorporation of UHMWPEO significantly improves the electrospinnability of solution and thermo-stability of nanofibers. Also, it is found that there is good miscibility or no phase separation in FD/UHMWPEO solutions. In vitro biological experiments show that the chitosan-modified FD/UHMWPEO nanofibers greatly facilitate the adhesion of endothelial cells and inhibit the attachment of monocytes. Thus, the designed FD-based nanofibers are promising bio-scaffolds in building tissue-engineered blood vessels.

Ternary organic solar cells with improved efficiency and stability enabled by compatible dual-acceptor strategy

To further elevate the power conversion efficiency (PCE) of organic solar cells (OSCs), ternary strategy is one of the most efficient methods via simply incorporating a suitable third component. Here, a nonfullerene small molecule acceptor MOITIC was incorporated into the state-of-art PM6:Y6 binary system to further enhance the photovoltaic performance. Detailed investigation revealed that MOITIC exhibited a good miscibility and compatibility with Y6, forming alloy-like acceptors in the ternary blends. The alloy-like phase promoted the phase separation and optimized the morphology of ternary blend, which afforded higher and more balanced carrier mobility and reduced charge recombination in devices. Moreover, the larger energy offset between PM6 and MOITIC:Y6 acceptor alloy is beneficial to enhance open-circuit voltage (Voc) of corresponding devices. As a consequence, the optimized ternary OSC (PM6:Y6:MOITIC = 1:1:0.1) showed a significantly increased PCE of 17.1% with simultaneously enhanced Voc of 0.882 V, short-circuit current density (Jsc) of 25.6 mA cm−2, and fill factor (FF) of 75.7%, which has about 9% enhancement compared to the control binary PM6:Y6 (15.7%). In addition, the optimized ternary device exhibited better stability. This work indicates that ternary strategy via combining two compatible small molecule acceptors is effective to simultaneously improve the efficiency and stability of OSCs.

Mechanical and Structural Properties of Nanocarbon Particles Reinforced in Plasticised Polylactic Acid for High Strength Application

High strength application of biopolymers requires good mechanical strength. The tensile properties of polylactic acid (PLA) are relatively low for major industrial applications such as packaging, biomedical and automobile spare parts. In this study, the mechanical strength of polylactic acid was enhanced with nanocarbon isolated from diesel engine combustion soot. The isolated nanocarbon was characterised using spectrometry and Fourier transform infrared (FTIR) spectroscopy analysis. After that, the nanocarbon was used as a reinforcement in plasticised PLA to produce a composite. The PLA-nanocarbon composite was produced using the compression moulding technique. The nanocarbon composition was varied between 2 wt% and 8 wt% in the PLA matrix. The tensile, hardness and morphological properties of the composite were analysed with the tensile test, hardness test, optical microscope and X-ray diffraction (XRD) analysis. The ultraviolet (UV) spectrometer and FTIR analysis results confirmed the successful isolation of nanocarbon from the diesel engine combustion soot. The tensile and hardness properties of the PLA matrix increased with addition of nanocarbon. The morphological images showed good miscibility between the PLA and the nanocarbon reinforcement, responsible for the increase in mechanical properties. The potential use of the composite for high strength application showed great possibility based on the result obtained.

Recent Advances in Molecular Design of Organic Thermoelectric Materials

Recent Advances in Molecular Design of Organic Thermoelectric Materials

Effect of Chemical Penetration Enhancer-Adhesive Interaction on Drug Release from Transdermal Patch: Mechanism Study Based on FT-IR Spectroscopy, 13C NMR Spectroscopy, and Molecular Simulation.

Chemical penetration enhancers (CPEs) are commonly added into transdermal patches to impart improved skin permeation of drug. However, significant unexplained variability in drug release kinetics in transdermal patches is possible as a result of the addition of CPEs; investigations into the underlying mechanisms are still limited. In the present study, a diverse set of CPEs was employed to draw broad conclusions. Solubility parameters of CPEs and acrylate pressure-sensitive adhesive were calculated by molecular dynamics simulation and Fedors group contribution method to evaluate drug-adhesive miscibility. CPE-adhesive interaction was characterized by FT-IR study, 13C NMR spectroscopy, and molecular docking simulation. Results showed that release enhancement ratio (ERR) of CPEs for zolmitriptan was rank ordered as isopropyl myristate > azone > Plurol Oleique® CC497 > Span® 80 > N-methylpyrrolidone > Transcutol® P. It was found that solubility parameter difference (Δδ) between CPE and adhesive was negatively related with ERR. It was proved that hydrogen bonding between CPE and adhesive would increase drug release rate, but only if the CPE showed good miscibility with adhesive. CPE like isopropyl myristate, which had good miscibility with adhesive, could decrease drug-adhesive interaction leading to the release of drug from adhesive.

Controlling crystal precipitation in magnesium aluminosilicate glasses via thermoelectric coupling

MgO–Al2O3–SiO2 (MAS) the basic glass was prepared by the traditional melt-quenching method, whereas the glass-ceramics was produced by subjecting the glass to thermoelectric coupling treatment. The MAS glass-ceramics were characterized by FTIR, XPS, and SEM. Clearly, the extension of the heat-treatment time did not change the crystal grains number in the absence of an electric field. However, with the electric-field voltage increase,the crystal grains number in the MAS glass-ceramics gradually increased when the electric-field voltage became steady at 1200 V. At high temperatures, Ti4+ participates in the silicon-oxygen network with four coordinations and produces good miscibility with the melt. By the introduction of electric field into the glass, a high amount of titanium transforms from a titanium-oxide tetrahedron to a titanium-oxide octahedron. Titanium was separated from the silicon–oxygen network framework to form a crystal nucleus and promote crystal growth. This study provides insights into the relationship between electric-field and glass-ceramics nucleation.