Solid-liquid Phase Separation Research Articles

High Modulus, Strut-like poly(ether ether ketone) Aerogels Produced from a Benign Solvent.

Poly(ether ether ketone) (PEEK) was found to form gels in the benign solvent 1,3-diphenylacetone (DPA). Gelation of PEEK in DPA was found to form an interconnected, strut-like morphology composed of polymer axialites. To our knowledge, this is the first report of a strut-like morphology for PEEK aerogels. PEEK/DPA gels were prepared by first dissolving PEEK in DPA at 320 °C. Upon cooling to 50 °C, PEEK crystallizes and forms a gel in DPA. The PEEK/DPA phase diagram indicated that phase separation occurs by solid-liquid phase separation, implying that DPA is a good solvent for PEEK. The Flory-Huggins interaction parameter, calculated as χ12 = 0.093 for the PEEK/DPA system, confirmed that DPA is a good solvent for PEEK. PEEK aerogels were prepared by solvent exchanging DPA to water then freeze-drying. PEEK aerogels were found to have densities between 0.09 and 0.25 g/cm3, porosities between 80 and 93%, and surface areas between 200 and 225 m2/g, depending on the initial gel concentration. Using nitrogen adsorption analyses, PEEK aerogels were found to be mesoporous adsorbents, with mesopore sizes of about 8 nm, which formed between stacks of platelike crystalline lamellae. Scanning electron microscopy and X-ray scattering were utilized to elucidate the hierarchical structure of the PEEK aerogels. Morphological analysis found that the PEEK/DPA gels were composed of a highly nucleated network of PEEK axialites (i.e., aggregates of stacked crystalline lamellae). The highly connected axialite network imparted robust mechanical properties on PEEK aerogels, which were found to densify less upon freeze-drying than globular PEEK aerogel counterparts gelled from dichloroacetic acid (DCA) or 4-chlorphenol (4CP). PEEK aerogels formed from DPA were also found to have a modulus-density scaling that was far more efficient in supporting loads than the poorly connected aerogels formed from PEEK/DCA or PEEK/4CP solutions. The strut-like morphology in these new PEEK aerogels also significantly improved the modulus to a degree that is comparable to high-performance crosslinked aerogels based on polyimide and polyurea of comparable densities.

Dimensional analysis for sedimentation behavior of magnetorheological fluids

Magnetorheological fluids (MRFs) are primarily composed of magnetic particles suspended in carrier liquids, exhibiting a remarkable capacity to respond dynamically to external magnetic fields. However, the phenomenon of solid–liquid phase separation, attributable to particle sedimentation, represents a formidable barrier to the real-world application of MRFs in engineering contexts. As a result, it becomes critically imperative to conduct a thorough investigation into the sedimentation behavior of MRFs under static conditions, to significantly enhance their practical utility. In the study, computational analysis through COMSOL was utilized to elucidate the sedimentation dynamics of MRFs. The findings indicated that particle sedimentation harbored the potential to induce localized turbulence within the flow field, thereby significantly impacting the sedimentation dynamics of MRFs. The motion of particles consistently followed a pattern where sedimentation rates decreased as the viscosity of the carrier liquids increased. Moreover, the elucidation of the settling behavior of MRFs was facilitated by the introduction of two dimensionless numbers. These dimensionless numbers were employed to systematically characterize the temporal evolution of the supernatant height throughout the settling process. This investigation further explored the intricate interdependence between these dimensionless parameters via a comprehensive series of settling experiments. The outcomes of this research uncovered a unique pattern in the solid–liquid separation process of MRFs, marked by a phase of gradual initiation, followed by acceleration, and culminating in deceleration. However, as the viscosity of the carrier liquids increased, this pattern became less pronounced, gradually shifting toward a more uniform settling trajectory.

Performance Evaluation of a Multifunctional Road Marking Coating for Tunnels Based on Nano SiO2 and TiO2 Modifications

Multifunctional road marking coatings with the functions of high-temperature stability, degradation of exhaust gas, and self-cleaning are of great significance for the safe operation and environmental protection of tunnels. This article uses active acrylic resin and an organosilicon hydrophobic agent as the base material, selects expanded vermiculite and glass microspheres as insulation fillers, and uses ammonium polyphosphate, pentaerythritol, melamine, and aluminum hydroxide as high-thermal-stability systems to prepare a two-component road marking coating base material. Then, nano SiO2 and modified nano TiO2 are added as modifiers to prepare a multifunctional road marking coating for tunnels. The physical and chemical properties of multifunctional road marking coatings are evaluating based on laboratory tests including thermogravimetry and derivative thermogravimetry, differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, exhaust degradation, and contact angle tests. The results indicate that the developed multifunctional road marking coating effectively reduces the thermal conductivity of the carbon layer through physical changes in the flame retardant system and the heat resistance formed by the high breaking bond energy of nano SiO2 during the combustion process. It forms a ceramic-like structure of titanium pyrophosphate with nano TiO2 that is beneficial for improving flame retardancy without generating harmful volatile gases and has good flame retardant properties. N–V co-doping reduces the bandgap of TiO2, broadens the absorption range of visible light by nano TiO2, improves the catalytic efficiency of visible light, and achieves the degradation efficiency of the four harmful components NOx, HC, CO, and CO2 in automotive exhaust by 23.4%, 8.3%, 2.5%, and 2.9%, respectively. The solid–liquid phase separation in the multifunctional road marking coating in the tunnel causes the formation and accumulation of nano SiO2 and TiO2 particles on the coating surface, resulting in a microstructure similar to the “micro–nano micro-convex” on the lotus leaf surface and making a water droplet contact angle of 134.2° on the coating surface.

Liquid-solid phase separation and recycling of permalloys in liquid Mg

Liquid-solid phase separation of permalloy in liquid Mg results in selectively dissolved Ni, which provides a unique opportunity for the design of immiscible heterogeneous composite materials and the comprehensive metal recycling of permalloy scraps. A guideline of the alloy design for the liquid-solid phase separation system was proposed. The effects of immersion temperature and time on the Ni extraction were studied by an experimental method. The diffusion behavior of Ni from the permalloy to liquid Mg and the microstructure evolution in the permalloy during the liquid-solid phase separation were discussed. The results show that the Ni in the permalloy was quickly extracted into the liquid Mg and formed an Mg-Ni alloy, while the other components such as Fe, Co, and Mn were held back in the phase-separated permalloy. The phase-separated permalloy with the solidified Mg exhibits a three-dimensional (3D) Fe/Mg bicontinuous composite structure. Furthermore, simple treatments were carried out for the reaction products such as the Fe/Mg bicontinuous composite and the Mg-Ni alloy, and the recycling strategies for functionalization of these treated reaction products were provided. A 3D porous Fe-based alloy with electromagnetic interference (EMI) shielding efficiency of 52 dB can be obtained if Mg is removed from the Fe/Mg bicontinuous composite. Instead of the complete separation of pure Ni from the recycled Mg-Ni alloy by vacuum distilling, the Mg-Ni alloy can be enriched into Mg2Ni as an initial hydrogen storage material.

Solid-liquid phase separation diffused Nd-Fe-B sintered magnets by using DyH3 nanopowder realize high-efficiency coercivity improvement and overcome thickness limit

In this study, new grain boundary diffusion (GBD) technology is applied to Nd-Fe-B sintered magnets with different thicknesses utilizing DyH3 nanopowder. The weight ratio is 0.25 wt.%. For comparison, the GBD processes include solid-liquid phase separation diffusion (SepD) and solid-liquid phase simultaneous diffusion (SimD). The magnetic properties and microstructure of GBD magnets with different thicknesses are thoroughly investigated. The comprehensive magnetic properties of SepD magnets are higher than SimD magnets. When the magnets are 8 mm thick, the SepD magnet obtains a coercivity of 18.10 kOe, which is higher than the SimD magnets (17.00 kOe). It was determined that SepD can manufacture thick magnets with excellent coercivity. In SepD magnets, the Dy element diffusion distance is deeper than in SimD magnets. For SepD magnets, there are core-shell structures formed in the surface region, while there are anti-core-shell structures that are unfavorable to magnetic properties in the surface region of the SimD magnets. The enhanced coercivity and temperature stability of the SepD magnets is primarily due to the more continuous core-shell structures produced by the deeper diffusion depth of the Dy element. This study will provide more theoretical guidance for the application of SepD in magnets with different thicknesses.

Preparation and properties of high-energy-density aluminum/boron-containing gelled fuels

Energetic nanofluid fuel has caught the attention of the field of aerospace liquid propellant for its high energy density (HED), but it suffers from the inevitable solid–liquid phase separation problem. To resolve this problem, herein we synthesized the high-Al-/B-containing (up to 30% (mass)) HED gelled fuels, with low-molecular-mass organic gellant Z, which show high net heat of combustion (NHOC), density, storage stability, and thixotropic properties. The characterizations indicate that the application of energetic particles to the gelled fuels obviously destroys their fibrous network structures but can provide the new particle–gellant gelation microstructures, resulting in the comparable stability between 1.0% (mass) Z/JP-10 + 30% (mass) Al or B and pure JP-10 gelled fuel. Moreover, the gelled fuels with high-content Al or B exhibit high shear-thinning property, recovery capability, and mechanical strength, which are favorable for their storage and utilization. Importantly, the prepared 1.0% (mass) Z/JP-10 + 30% (mass) B (or 1.0% (mass) Z/JP-10 + 30% (mass) Al) shows the density and NHOC 1.27 times (1.30) and 1.43 times (1.21) higher than pure JP-10, respectively. This work provides a facile and valid approach to the manufacturing of HED gelled fuels with high content of energetic particles for gel propellants.

Crystallization-driven formation poly (l-lactic acid)/poly (d-lactic acid)-polyethylene glycol-poly (l-lactic acid) small-sized microsphere structures by solvent-induced self-assembly

Improving hydrophobicity through the regulation of surface microstructures has attracted significant interest in various applications. This research successfully prepared a surface with microsphere structures using the Non-solvent induced phase separation method (NIPS). Poly(D-Lactic acid)-block-poly(ethylene glycol)-block-poly(D-Lactic acid) (PDLA-PEG-PDLA) block polymers were synthesized by ring-opening polymerization of D-Lactic acid (D-LA) using polyethylene glycol (PEG) as initiator. PLLA/PDLA-PEG-PDLA membrane with microscale microsphere morphology was fabricated using a nonsolvent-induced self-assembly method by blending the triblock copolymer with a poly(L-lactic acid) (PLLA) solution. In phase separation processes, the amphiphilic block copolymers self-assemble into micellar structures to minimize the Gibbs free energy, and the hydrophilic segments (PEG) aggregate to form the core of the micelles, while the hydrophobic segments (PDLA) are exposed on the outer corona resulting in a core-shell structure. The Stereocomplex Crystalline (SC), formed by the hydrogen bonding between PLLA and PDLA, can facilitate the transition from liquid-liquid phase separation to solid-liquid phase separation, and the PEG chain segments can enhance the formation of SC. The membrane, prepared by adjusting the copolymer content and PEG chain length, exhibited adjustable microsphere quantity, diameter, and surface roughness, enabling excellent hydrophobicity and controlled release of oil-soluble substances.

ε-Polylysine and soybean protein isolate form nanoscale to microscale electrostatic complexes in solution: properties, interactions and as antimicrobial edible coatings on citrus

A feasible approach to enhance the antimicrobial efficacy of ε-polylysine (PL) in applications is to form delivery complexes with delicate structures and good dispersion properties. This work aims to study the multiscale structures, properties and interactions, and edible coating applications of the electrostatic complex formed by PL and soy protein isolate (SPI). When the mass ratio of SPI to PL (SE) was between 5 and 15, especially 11, microscale solid-liquid phase separation occurred in the system due to the small absolute zeta potential. When the SE was in the range of 15–20, the system formed a stable nanoscale suspension, the average particle size and zeta potential were 191 nm and −20 mV, respectively. The physicochemical properties of the complexes were investigated including the colloidal properties, spectroscopy and interactions analysis, viscosity, contact angle, and antimicrobial activities against Escherichia coli, Staphylococcus aureus, and Penicillium expansum. Finally, the in vivo application on citrus demonstrated that the nanoscale PL/SPI electrostatic complex (SE = 20) as functional coatings has both barrier and antimicrobial activities. The study provides a novel application strategy for PL and nanoscale electrostatic complexes as postharvest coatings.

The strategy of solid-liquid phase separation diffusion with DyH3 to approach a trade-off between properties and cost for sintered Nd-Fe-B magnets

Approach a trade-off between properties and cost for sintered Nd-Fe-B magnets in grain boundary diffusion (GBD) helps widen their application. In this study, we fabricated GBD Nd-Fe-B magnets via solid-liquid phase separation diffusion (SepD) with DyH3 nanopowder as the diffusion source. Investigations and comparisons with the traditional solid-liquid phase simultaneous diffusion (SimD) magnets were made regarding the liquid phase diffusion (LPD) temperature, magnetic characteristics, microstructures, diffusion coefficient, and domain morphology of SepD magnets. In addition, the cost was calculated and compared with TbH3 SepD magnets. It is determined that the optimal LPD temperature of DyH3 was 625 °C. Compared to the SimD magnet, Dy had a faster LPD rate in the SepD magnet, which leads to a deeper diffusion depth of 1200 µm. Consequently, the SepD magnet develops more core-shell structures. Additionally, SepD could prevent the development of anti-core-shell formations in the magnet's surface region. As a result, the SepD magnet had higher comprehensive magnetic properties and coercivity temperature stability. Impressively, compared to TbH3 SepD magnets, the cost of per kOe coercivity enhancement for per kilogram magnets of DyH3 SepD magnets can be reduced by more than 50 %.

Quantification of Surface Tension Effects and Nucleation-and-Growth Rates during Self-Assembly of Biological Condensates.

Liquid-solid and liquid-liquid phase separation (PS) drives the formation of functional and disease-associated biological assemblies. Principles of phase equilibrium are here employed to derive a general kinetic solution that predicts the evolution of the mass and size of biological assemblies. Thermodynamically, protein PS is determined by two measurable concentration limits: the saturation concentration and the critical solubility. Due to surface tension effects, the critical solubility can be higher than the saturation concentration for small, curved nuclei. Kinetically, PS is characterized by the primary nucleation rate constant and a combined rate constant accounting for growth and secondary nucleation. It is demonstrated that the formation of a limited number of large condensates is possible without active mechanisms of size control and in the absence of coalescence phenomena. The exact analytical solution can be used to interrogate how the elementary steps of PS are affected by candidate drugs.

Super-low energy consuming CO2 capture triggered by weak hydrogen bonds in solid-liquid phase separation

Super-low energy consuming CO2 capture triggered by weak hydrogen bonds in solid-liquid phase separation

Integrating Fly Ash-Controlled Surface Morphology and Candle Grease Coating: Access to Highly Hydrophobic Poly (L-lactic Acid) Composite for Anti-Icing Application

New ways of recycling fly ash are of great significance for reducing the environmental pollution. In this work, biodegradable hydrophobic poly (L-lactic acid)/fly ash composites for anti-icing application were successfully fabricated via a facile solvent-volatilization-induced phase separation approach. A silane coupling agent of 3-(Trimethoxysilyl) propyl methacrylate was used to decorate a fly ash surface (FA@KH570) for strengthening the interface bonding between fly ash and poly (L-lactic acid). Moreover, FA@KH570 could obviously enhance the crystallinity of poly (L-lactic acid) (PLLA)/FA@KH570 composites, which accelerated the conversion from the liquid-liquid to the liquid-solid phase separation principle. Correspondingly, the controllable surface morphology from smooth to petal-like microspheres was attained simply by adjusting the FA@KH570 content. After coating nontoxic candle grease, the apparent contact angle of 5 wt% PLLA/FA@KH570 composite was significantly increased to an astonishing 151.2°, which endowed the composite with excellent anti-icing property. This strategy paves the way for recycling waste fly ash and manufacturing hydrophobic poly (L-lactic acid) composite for potential application as an anti-icing material for refrigerator interior walls.

Fabrication of polycaprolactone/heparinized nano fluorohydroxyapatite scaffold for bone tissue engineering uses

In this study, some polycaprolactone (PCL)/heparinized nano fluorohydroxyapatite (H-nFHA) scaffolds were fabricated with different amounts of H-nFHA using solid-liquid phase separation and freeze-drying methods. The scaffolds were characterized using Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy techniques, and compressive test. Their biological behavior also was studied using Alkaline phosphatase activity and MTT assay. The results showed that adding H-nFHA to the PCL matrix improves MG-63 cells adhesion and proliferation and they also showed that heparinizing the nFHA particles improves the mechanical properties and dispersion of the nFHA particles in the PCL matrix for bone tissue engineering uses.

Modulating the Mixing Gibbs Free Energy to Enhance Solid–Liquid Phase Separation for High‐Performance Organic Solar Cells

AbstractOrganic solar cells (OSC) feature a hierarchical structure with the electron donor/acceptor layer sandwiched by anode and cathode, which raises the importance of controlling the molecular crystal orientation, domain size, and vertical distribution to facilitate the charge collection at electrodes. However, the similar conjugated backbone of donor/acceptor material and fast film‐formation kinetics have led to spinodal‐decomposition‐orientated phase separation that result in the film presenting an intimately mixed morphology and random molecular orientation. To solve the issue, the mixing Gibbs free energy‐triggered solid–liquid phase separation during the film formation process is enhanced by solidifying one component and solvating the other based on a liquid additive. Following the liquid evaporation process, a favorable vertical distribution is obtained. Meanwhile, the prolonged solvation process enlarges the domain size and assists the molecules to diffuse and orient properly, enabling better exciton/charge dynamics during the power conversion processes. As a result, the fabricated devices exhibit a fill factor over 80% and an efficiency of 18.72%, which is one of the top efficiencies for binary OSCs. Insights and a methodology is provided here to manipulate the organic donor/acceptor phase separation in terms of mixing Gibbs free energy.

New grain boundary diffusion strategy of Nd-Fe-B sintered magnets to achieve breakthroughs in Tb-availability and thick limitation

Grain boundary diffusion (GBD) Nd-Fe-B sintered magnets were prepared using a newly developed solid-liquid phase separation diffusion (SepD) technique, as well as a currently popular solid-liquid phase simultaneous diffusion (SimD) technique. The magnetic properties, microstructures, and magnetic domain morphologies of the magnets with different Tb contents diffused using the two techniques were then investigated. A SepD magnet using 0.25 wt% Tb exhibited a similar coercivity and a stronger maximum energy product compared to a SimD magnet with 0.50 wt% Tb, demonstrating high Tb availability. Moreover, by using the new diffusion technique, Tb could diffuse deeper into the magnet and distribute more homogeneously around the surface region of the Nd2Fe14B crystal grains, forming the crucial core-shell structure without undesirable enrichment in the surface area of the magnet. As a result, the squareness factor increased noticeably from 0.842 for the current technique diffused magnet to 0.925 for the new technique diffused magnet with a thickness of 8 mm.

Hydration makes a difference! How to tune protein complexes between liquid-liquid and liquid-solid phase separation.

Understanding how protein rich condensates formed upon liquid-liquid phase separation (LLPS) evolve into solid aggregates is of fundamental importance for several medical applications, since these are suspected to be hot-spots for many neurotoxic diseases. This requires developing experimental approaches to observe in real-time both LLPS and liquid-solid phase separation (LSPS), and to unravel the delicate balance of protein and water interactions dictating the free energy differences between the two. We present a vibrational THz spectroscopy approach that allows doing so from the point of view of hydration water. We focus on a cellular prion protein of high medical relevance, which we can drive to undergo either LLPS or LSPS with few mutations. We find that it is a subtle balance of hydrophobic and hydrophilic solvation contributions that allows tuning between LLPS and LSPS. Hydrophobic hydration provides an entropic driving force to phase separation, through the release of hydration water into the bulk. Water hydrating hydrophilic groups provides an enthalpic driving force to keep the condensates in a liquid state. As a result, when we modify the protein by a few mutations to be less hydrophilic, we shift from LLPS to LSPS. This molecular understanding paves the way for a rational design of proteins.

The PRALINE database: protein and Rna humAn singLe nucleotIde variaNts in condEnsates.

Biological condensates are membraneless organelles with different material properties. Proteins and RNAs are the main components, but most of their interactions are still unknown. Here, we introduce PRALINE, a database for the interrogation of proteins and RNAs contained in stress granules, processing bodies and other assemblies including droplets and amyloids. PRALINE provides information about the predicted and experimentally validated protein-protein, protein-RNA and RNA-RNA interactions. For proteins, it reports the liquid-liquid phase separation and liquid-solid phase separation propensities. For RNAs, it provides information on predicted secondary structure content. PRALINE shows detailed information on human single-nucleotide variants, their clinical significance and presence in protein and RNA binding sites, and how they can affect condensates' physical properties. PRALINE is freely accessible on the web at http://praline.tartaglialab.com.

Control of the Crystallization and Phase Separation Kinetics in Sequential Blade‐Coated Organic Solar Cells by Optimizing the Upper Layer Processing Solvent

AbstractSequential deposition of the active layer in organic solar cells (OSCs) is favorable to circumvent the existing drawbacks associated with controlling the microstructure in bulk‐heterojunction (BHJ) device fabrication. However, how the processing solvents impact on the morphology during sequential deposition processes is still poorly understood. Herein, high‐efficiency OSCs are fabricated by a sequential blade coating (SBC) through optimization of the morphology evolution process induced by processing solvents. It is demonstrated that the device performance is highly dependent on the processing solvent of the upper layer. In situ morphology characterizations reveal that an obvious liquid–solid phase separation can be identified during the chlorobenzene processing of the D18 layer, corresponding to larger phase separation. During chloroform (CF) processing of the D18 layer, a proper aggregation rate of Y6 and favorable intermixing of lower and upper layers results in the enhanced crystallinity of the acceptor. This facilitates efficient exciton dissociation and charge transport with an inhibited charge recombination in the D18/CF‐based devices, contributing to a superior performance of 17.23%. These results highlight the importance of the processing solvent for the upper layer in the SBC strategy and suggest the great potential of achieving optimized morphology and high‐efficiency OSCs using the SBC strategy.

Microbial biofilms are shaped by the constant dialogue between biological and physical forces in the extracellular matrix.

Microbial biofilms are shaped by the constant dialogue between biological and physical forces in the extracellular matrix.

A phase separation process induced by pH change for purification of His-tagged protein at low salt concentration

Protein purification is critical for protein research and enzyme manufacture, and efficient purification methods with low cost have a high priority. In this study, the difference in solubility between His-tagged protein and nontagged protein led to a liquid-solid phase separation at neutral pH and low salt concentration and purified His-tagged protein to some extent. The investigation of impurity in the precipitate indicated that solvation behavior varied from several oligo-amino acid tagged proteins. Among them, proteins with oligo-Lys, oligo-Trp and oligo-Arg obviously precipitated at low salt concentration and weak acidic pH, which is similar to that for the precipitation of His-tagged protein. Further study suggested that proteins with oligo-Lys, oligo-Trp and oligo-Arg remained a precipitate state while His-tagged protein dissolved at a slightly higher pH value. Based on these finding, a method was developed for the purification of His-tagged protein via phase separation induced by pH (PSIP) at low salt concentration. Though the yield and purity of protein purified by PSIP were slightly inferior to that by immobilized metal ion affinity chromatography (IMAC), PSIP was a high-throughput and low-cost method for purification of His-tagged proteins. Beyond the purification process, the various solvation behaviors of proteins with different oligo-amino acid also provide a reference for solvation research of protein.