Pore Walls Research Articles

Porous PVDF composites with ultralow percolation threshold for wide-range dynamic and static pressure sensing

Porous conductive polymer composites are very attractive for static pressure sensing due to high sensitivity and good elasticity contributed by the porous structure, while they are hard to detect dynamic pressure. Herein, we report a porous conductive poly (vinylidene fluoride) (PVDF) composite capable of detecting static and dynamic pressure over a pressure range of 0–1 MPa, which was fabricated by melt mixing PVDF, polyethylene oxide (PEO) and carbon nanofillers, followed by etching PEO with water. Such porous PVDF composites have a very low percolation threshold (0.035 wt%) of carbon nanostructures (i.e., branched carbon nanotubes) thanks to the selective distribution of conductive fillers in the pore wall after etching. At the same time, the pore size and porosity of the porous PVDF composites can be tuned by the molecular weight (Mw) and blending ratios of two polymers, leading to the kinetically-tailorable blend morphology for tunable mechanical and electrical properties. The as-fabricated porous PVDF composites with a good combination of mechanical properties and electrical conductivities, which can be used as pressure sensors toward wide-range (0–1 MPa) dynamic and static pressure sensing. Such pressure sensors demonstrate potential applications in detecting the degree of finger bending, distinguishing the walking and running, and monitoring a series of technical movements in playing soccer, i.e., static and dynamic exercises.

Quasielastic neutron scattering study on low-hydrated myoglobin inside silica nanopores

In this study, nanosecond-scale dynamics of low-hydrated myoglobin (Mb) encapsulated in mesoporous silica (MPS) with 7.8 nm pores was investigated by using high resolution (energy resolution: 1 μeV) neutron backscattering spectroscopy. The apparent hydration level of the encapsulated myoglobin was 0.06, which was deduced by assuming a uniform distribution of water within myoglobin encapsulated mesoporous silica. The mean square displacement of myoglobin derived from an elastic fixed-window scan was essentially proportional to temperature in the range 120–300 K, indicating the absence of dynamical transition induced by the onset of translational diffusion in the hydration D2O. Since the width of quasielastic neutron scattering (QENS) peaks of the encapsulated Mb was Q-independent at 220, 240, and 265 K, the observed nanosecond-scale dynamics was attributed to internal motions of the encapsulated Mb, such as slow motions of amino acid groups or side chains. The fraction of immobile H-atoms in Mb was estimated to be above 0.8, which was larger than that for a free protein with a similar molecular weight to Mb. The large immobile fraction indicates that the nanosecond-scale motions of amino acid residues and side chains in the vicinity of the pore wall are restricted by the interfacial interactions with the rigid pore wall.

Mild preparation of hyaluronic acid/silk fibroin sponges by modified crosslinking method

The composites composed of hyaluronic acid (HA) and silk fibroin (SF) exhibit great potential in diverse biomedical applications. However, the utilization of commercial crosslinkers such as 1,4-butanediol diglycidyl ether (BDDE) for crosslinking HA typically necessitates harsh conditions involving strong alkaline, which greatly limits its potential applications. In this study, a mild modified approach was developed to fabricate HA/SF blend sponges crosslinked by BDDE without alkaline conditions. The blend solutions were cryo-concentrated to induce crosslinking reactions. The mechanism of freezing crosslinking was elucidated by investigating the effects of ice crystal growth and HA molecular weight on the degree of crosslinking. The results revealed that HA achieved efficient crosslinking when its molecular weight exceeds 1000 kDa and freezing temperatures ranged from −40 °C to −20 °C. After introducing SF, multiple crosslinks were formed between SF and HA chains, producing water-stable porous sponges. The SEM results demonstrated that the introduction of SF effectively enhanced the interconnectivity between macropores through creating subordinate holes onto the pores wall. Raising the SF content significantly enhanced compression strength, resistance to enzymatic degradation and cell viability of blend sponges. This study provides a novel strategy for designing bioactive HA/SF blend sponges as substitutes for tissue repair and wound dressing.

Atomically integration of O-bridged Co-Fe hetero-pairs as tandem photocatalyst towards highly efficient hydroxyl radicals production

Photocatalytic Fenton-coupled oxygen reduction reaction (ORR) is a promising strategy generated by •OH. Single-atom catalysts (SACs), featuring high atom utilization, exhibit superior catalytic activity. However, effectively catalyzing the two steps on the activity site remains a challenge. Herein, a novel Co-Fe hetero-atom pair tandem photocatalyst was precisely constructed by pre-designing the structure of covalent organic frameworks (COFs) and the introduction strategies of active sites. Thanks to the synergism of adjacent Co-Fe atoms, Co-Fe-COF presents highly efficient hydroxyl radicals production following the process of O2+H2O→H2O2→•OH. Additionally, immobilization of atom pairs on the pore walls of COF can boost the enrichment for contaminants, thus increasing the •OH utilization rates. Theoretical simulations reveal proximity electronic effect of O-bridged Co-Fe not only thermodynamically promotes the formation of OOH*, but also dynamically activates the self-healing cycle of Fe(II)/Fe(III). This work provides a novel program for designing high-performance tandem catalysts.

Two-Dimensional Cu(II)-MOF with Lewis Acid-Base Bifunctional Sites for Chemical Fixation of CO2 and Bioactive 1,4-DHP Synthesis via Hantzsch Condensation.

Five- and six-membered heterocycles containing nitrogen or oxygen have been considered as privileged scaffolds in organic chemistry and the chemical industry because of their usage in high-value commodities. Herein, we report a two-dimensional (2D) Cu(II)-based MOF catalyst, IITKGP-40, via the strategic employment of ample Lewis acid-base bifunctional sites (open metal nodes and free pyrazine moieties) along the pore wall. IITKGP-40 could convert toxic CO2 to cyclic carbonates in an atom-economical manner under solvent-free conditions and aromatic aldehyde to bioactive 1,4-DHPs via Hantzsch condensation. Exceptional catalytic performance (99%) and turnover number under mild reaction conditions for CO2 fixation using sterically hindered styrene oxide, and good-to-excellent yields for a wide range of aromatic aldehydes toward 1,4-dihydropyridines (1,4-DHPs) make IITKGP-40 promising as a multipurpose heterogeneous catalyst. Moreover, to demonstrate the practical utility of the catalyst, two biologically important drug molecules, diludine and nitrendipine analogue, have also been synthesized. IITKGP-40 is recyclable for at least three consecutive runs without significant loss of activity, making it promising for real-time applications.

Wettability, imbibition and interdiffusion of lithium-based water-in-salt electrolytes in nanoporous carbon in relation to energy storage: A neutron radiography study

Superconcentrated lithium salt electrolytes, or lithium-based Water-in-Salt (WiS) electrolytes emerge as alternative electrolytes in supercapacitors and advanced batteries, such as the Li–O2 ones, especially when combined with a mesoporous carbon with very high surface area. In this work, we analyze the wettability, imbibition, and diffusivity of very concentrated lithium salts in a bimodal mesoporous carbon with pores of 5 nm and 25 nm in diameter. For the first time a neutron radiography technique is used to determine the imbibition and interdiffusion of lithium salts in mesoporous carbon. We found that a 20 m LiTFSI aqueous solution wets the surface of graphite and mesoporous carbon better than water. As a consequence, this WiS electrolyte is embedded rather fast in the mesoporous carbon by the action of capillary forces, exhibiting an intrinsic permeability K = (1.16 ± 0.03).10−18 m2. Finally, by resorting to the different cross-section of the 6Li and 7Li isotopes for the neutron capture, we could analyze the diffusion of LiCl in D2O confined in the mesoporous carbon. The interdiffusion coefficient of the confined LiCl is 5.0 10−7 cm2 s−1, corresponding to a tortuosity coefficient τ = 1.32. This moderate confinement effect results from the strong ion association of the LiCl that precludes the electrostatic interactions of Li+ ions with the negative charge on the pore walls. In summary, the combined properties of the lithium-based WiS electrolytes and the mesoporous carbon allow us to glimpse their use in supercapacitors and Li–O2 batteries.

Crystalline Olefin-Linked Chiral Covalent Organic Frameworks as a Platform for Asymmetric Catalysis.

The construction of olefin-linked chiral covalent organic frameworks (COFs) with high crystallinity is highly desirable while remains great challenge due to the poor reversibility of the formation reaction for the olefin linkages during the in situ structural self-healing process. Herein, we successfully synthesized two sets of enantiomeric olefin-linked COFs. The chiral catalytic groups are uniformly distributed on the pore walls of COFs, resulting in the full exposure of catalytic sites to the reactants in asymmetric catalysis. The as-prepared (R)/(S)-CCOF8 exhibits excellent catalytic performance with exceeding 99 % enantiomeric excess in the enantioselective electrophilic amination reaction. Moreover, the heterogeneous chiral catalysts are conveniently recycled and could maintain the performance after ten catalytic cycles. Our findings expand the scope to construct stable and crystalline chiral COFs for the asymmetric catalysis.

Crystalline Olefin‐Linked Chiral Covalent Organic Frameworks as a Platform for Asymmetric Catalysis

AbstractThe construction of olefin‐linked chiral covalent organic frameworks (COFs) with high crystallinity is highly desirable while remains great challenge due to the poor reversibility of the formation reaction for the olefin linkages during the in situ structural self‐healing process. Herein, we successfully synthesized two sets of enantiomeric olefin‐linked COFs. The chiral catalytic groups are uniformly distributed on the pore walls of COFs, resulting in the full exposure of catalytic sites to the reactants in asymmetric catalysis. The as‐prepared (R)/(S)‐CCOF8 exhibits excellent catalytic performance with exceeding 99 % enantiomeric excess in the enantioselective electrophilic amination reaction. Moreover, the heterogeneous chiral catalysts are conveniently recycled and could maintain the performance after ten catalytic cycles. Our findings expand the scope to construct stable and crystalline chiral COFs for the asymmetric catalysis.

Gate-All-Around Nanopore Osmotic Power Generators.

Nanofluidic channels in a membrane represent a promising avenue for harnessing blue energy from salinity gradients, relying on permselectivity as a pivotal characteristic crucial for inducing electricity through diffusive ion transport. Surface charge emerges as a central player in the osmotic energy conversion process, emphasizing the critical significance of a judicious selection of membrane materials to achieve optimal ion permeability and selectivity within specific channel dimensions. Alternatively, here we report a field-effect approach for in situ manipulation of the ion selectivity in a nanopore. Application of voltage to a surround-gate electrode allows precise adjustment of the surface charge density at the pore wall. Leveraging the gating control, we demonstrate permselectivity turnover to enhanced cation selective transport in multipore membranes, resulting in a 6-fold increase in the energy conversion efficiency with a power density of 15 W/m2 under a salinity gradient. These findings not only advance our fundamental understanding of ion transport in nanochannels but also provide a scalable and efficient strategy for nanoporous membrane osmotic power generation.

Structural characterization of Porphyra haitanensis extracts and their effects on structure, physicochemical properties, and in vitro digestibility of corn starch

Porphyra haitanensis with many bioactive components has great prospects for application in the functional food, pharmaceutical, and cosmeceutical industries. In this study, two sequentially extracted fractions (PhE1 & PhE2) were isolated and structurally characterized. The results showed that PhE1 was mainly composed of protein (36.82%) and neutral sugar (32.43%), while PhE2 mainly contained neutral sugar (58.70%). Both had galactose as main monosaccharides, PhE2 also contained a small amount of glucose. To widen the application of PhEs in starchy foods, they were added to corn starch (CS) system and co-gelatinized. Rheological tests indicated that PhEs could effectively affect gel strength of CS. The addition of PhEs effectively inhibited the content of leached amylose in CS gelatinization system except those at an addition of 5% PhE1 and 5% PhE2. FT-IR data suggested that PhE1 could improve the short-range order, but PhE2 showed no significant effects. SEM images showed that the pore wall of the composites thickened, and the network structure became relatively ordered. In vitro tests, PhEs significantly reduced the contents of rapidly digestible starch, and PhE1 presented better effects. Therefore, PhEs may be used as potential materials to delay the digestion of CS and related products.

СТРУКТУРА ПОР ЯЧЕИСТОГО БЕТОНА С ОТХОДАМИ СТЕКЛОБОЯ ЭЛЕКТРОННО-ЛУЧЕВЫХ ТРУБОК

To date, the issue of handling toxic unsorted waste of cathode ray tubes (CRT) glass cullet remains relevant. The present paper proposes to replace part of the fine aggregate of cellular concrete intended for sound, heat or radiation protection with CRT glass waste heat-treated in the presence of a sodium hydroxide solution. The purpose of the research is to study the structure formation of the cellular concrete pores in case of replacement of part of the aggregate. The microscopy of the samples fracture was studied both visually and using software that made it possible to estimate the pore size when convert-ing the image to the relief mode. The study showed that the aggregate replacement results not only in quantitative changes in pore size, but also in qualitative changes related to the mechanism of the pore structure formation. Thus, when adding unsorted waste heat-treated in an alkaline environment, with a particle diameter of no more than 630 μm, there was a decrease in pore size and a decrease in size distribution compared with the reference sample. The changes are caused by structure formation, which can be divided into two stages - the formation of conglomerates and their swelling. With a decrease in the diameter of the part of the waste of a maximum size of 90 μm, a decrease in the pore size was recorded compared to the reference value, but due to the concrete skeleton formation before the end of gas development, destruction of the pore walls was observed.

Migration characteristics and geohazards risk analysis of swelling clay in clayey silt hydrate sediments

The safe and long-term hydrate production in loose clayey silt sediments with high clay content is one of the research priorities, in which the fines migration is one of the key factors. The characteristics of montmorillonite swelling and dispersion make its migration behavior more challenging, which causes the evolution of reservoir seepage properties and potential geohazards risk cannot be predict. The migration behavior of montmorillonite induced by pore water was investigated, and discusses its potential impact on the geomechanical properties of the reservoir. The results show that the combined effects of montmorillonite swelling, which creates favorable conditions for blockage, and migration, which exacerbates permeability decline, make montmorillonite have a much greater effect on seepage characteristics in clayey silt sediments than illite. Higher montmorillonite content and low salinity increase the particle concentration in the pore water, which creates a source of particles for blockage. The low reynolds number indicates that the particles mainly detach from the pore wall with rolling in laminar flow and the lifting force can be neglected. As a result of this combined effect, the montmorillonite is more likely to readsorb and block the pore throat with bridging. This work will help to understand the migration behavior of montmorillonite in clayey silt formations with low permeability, which needs to be paid attention to when formulating gas production schemes and safety control strategies.

Self-Assembly of Ionic Superdiscs in Nanopores.

Discotic ionic liquid crystals (DILCs) consist of self-assembled superdiscs of cations and anions that spontaneously stack in linear columns with high one-dimensional ionic and electronic charge mobility, making them prominent model systems for functional soft matter. Compared to classical nonionic discotic liquid crystals, many liquid crystalline structures with a combination of electronic and ionic conductivity have been reported, which are of interest for separation membranes, artificial ion/proton conducting membranes, and optoelectronics. Unfortunately, a homogeneous alignment of the DILCs on the macroscale is often not achievable, which significantly limits the applicability of DILCs. Infiltration into nanoporous solid scaffolds can, in principle, overcome this drawback. However, due to the experimental challenges to scrutinize liquid crystalline order in extreme spatial confinement, little is known about the structures of DILCs in nanopores. Here, we present temperature-dependent high-resolution optical birefringence measurement and 3D reciprocal space mapping based on synchrotron X-ray scattering to investigate the thermotropic phase behavior of dopamine-based ionic liquid crystals confined in cylindrical channels of 180 nm diameter in macroscopic anodic aluminum oxide membranes. As a function of the membranes' hydrophilicity and thus the molecular anchoring to the pore walls (edge-on or face-on) and the variation of the hydrophilic-hydrophobic balance between the aromatic cores and the alkyl side chain motifs of the superdiscs by tailored chemical synthesis, we find a particularly rich phase behavior, which is not present in the bulk state. It is governed by a complex interplay of liquid crystalline elastic energies (bending and splay deformations), polar interactions, and pure geometric confinement and includes textural transitions between radial and axial alignment of the columns with respect to the long nanochannel axis. Furthermore, confinement-induced continuous order formation is observed in contrast to discontinuous first-order phase transitions, which can be quantitatively described by Landau-de Gennes free energy models for liquid crystalline order transitions in confinement. Our observations suggest that the infiltration of DILCs into nanoporous solids allows tailoring their nanoscale texture and ion channel formation and thus their electrical and optical functionalities over an even wider range than in the bulk state in a homogeneous manner on the centimeter scale as controlled by the monolithic nanoporous scaffolds.

Implications of Defect Density and Polymer Interactions for CO2 Capture on Amine-Functionalized MIL-101(Cr).

Rising anthropogenic carbon emissions have dire environmental consequences, necessitating remediative approaches, which includes use of solid sorbents. Here, aminopolymers (poly(ethylene imine) (PEI) and poly(propylene imine) (PPI)) are supported within solid mesoporous MIL-101(Cr) to examine effects of support defect density on aminopolymer-MOF interactions for CO2 uptake and stability during uptake-regeneration cycles. Using simulated flue gas (10 % CO2 in He), MIL-101(Cr)-ρhigh (higher defect density) shows 33 % higher uptake capacity per gram adsorbent than MIL-101(Cr)-ρlow (lower defect density) at 308 K, consistent with increased availability of undercoordinated Cr adsorption sites at missing linker defects. Increasing aminopolymer weight loadings (10-50 wt.%) within MIL-101(Cr)-ρlow and MIL-101(Cr)-ρhigh increases amine efficiencies and CO2 uptake capacities relative to bare MOFs, though both incur CO2 diffusion limitations through confined, viscous polymer phases at higher (40-50 wt.%) loadings. Benchmarked against SBA-15, lower polymer packing densities (PPI>PEI), weaker and less abundant van der Waals interactions between aminopolymers and pore walls, and open framework topology increase amine efficiencies. Interactions between amines and Cr defect sites incur amine efficiency losses but grant higher thermal and oxidative stability during uptake-regeneration cycling. Finally, >25 % higher CO2 uptake capacities are achieved for aminopolymer/MIL-101(Cr)-ρhigh under humid conditions, demonstrating promise for realistic applications.

Co-pyrolysis of coal with biomass residues and coke breeze for superior quality coke via hot pressing technology

Superior quality coke is essential in the metallurgical industry. However, the coking coal source is limited. The biomass or breeze could be blended into the coking coal to produce high-standard cokes by hot pressing technology. High-standard cokes should have low reactivity (chemical reaction intensity of coke and CO2 at high temperature) and high strength. The influences of biomass category and blending ratio on pore structure, reactivity and crushing strength of cokes were explored. Pore evolution during the coking process was studied by experiments and simulations to reveal the mechanism of producing high-quality cokes with biomass and breeze blended into coking coal via hot pressing technology. Results show that hot pressing technology can make high-quality cokes when the blending ratio of biomass or breeze is appropriate. When 5% bamboo, wood or straw is blended to produce hot-pressed coke, the coke reactivity decreases by 6.58%, 7.66% and 6.41% and the crushing strength increases to 1.15, 1.19 and 1.12 times when compared with coke in case of no blending and no pressing, respectively. The proper blending ratio of the three biomasses should be less than 15% because the coke quality deteriorates greatly when the blending ratio increases to 15%. If the breeze is mixed with coal to produce high-standard cokes under hot pressing conditions, the blending ratio should not exceed 30%. Hot pressing technology can reduce the coke pores when the biomass or breeze is blended into the coal with a low ratio. When 5% bamboo or 10% breeze is blended, the porosity of hot-pressed coke in the center region decreases by 5.69% and 4.02% than coke with no blending and no pressing, respectively. The low porosity contributes to the reduction of coke reactivity. The fewer pores, thicker pore walls and higher carbon matrix strength impede the growth of cracks, resulting in a higher coke crushing strength. Therefore, hot pressing technology can effectively enhance coke quality if the biomass or breeze is mixed with the coking coal with an appropriate blending ratio.

Indicative significance of the interfacial interactions between pore surface and soluble organic matter on the shale oil mobility

The exploration and exploitation of shale oil resources enhance the necessity to characterize the mobility of the occluded oil in shales. Up to now, the understanding of the controlling factors of shale oil mobility has mainly come from molecular dynamics simulation but lacking in-depth research on actual shales. Therefore, in this study, the effects of mineral composition, soluble organic matter (SOM) composition and wettability on the shale oil mobility were studied by X-ray diffraction, N2 adsorption, mercury intrusion, contact angle, chloroform bitumen and group component detection methods, comprehensively. The results show that: (1) The asphaltene contents and (Asphaltenes × Aromatics)/(Saturates × Resins) negatively and positively correlate with clay and carbonate mineral contents, respectively, while the I/S and illite contents present opposite trend with (Asphaltenes × Aromatics)/(Saturates × Resins). These correlations indicate that the SOM that confined in the pores constructed with carbonate minerals and illite present better flow potential. (2) Both δVt and δSSA negatively correlate with asphaltenes and (Asphaltenes × Aromatics)/(Saturates × Resins). That is, less pores and surfaces can be released by extraction for the shales with more asphaltenes. Therefore, it can be concluded that asphaltene is a negative factor for shale oil seepage. Additionally, the larger pores present better flow condition for shale oil, even for asphaltenes. (3) Pore surface wettability also significantly affects the shale oil mobility. The hydrophobicity of the pore wall greatly inhibits the shale oil flow, especially for the mesopores and macropores. The pattern diagram was established to illustrate the effect of the interactions between pore surfaces and shale oil components on the movable potential. Based on our research, mineral composition, group composition and pore surface wettability are efficient parameters for the shale oil mobility evaluation based on the interfacial interaction theory, and the “sweet spots” for shale oil seepage of the Jiyang Depression are the shales with more illite, carbonate, saturates and relatively low lipophilicity.

Photogeneration of Hydrogen: Insights from a Pt(II)‐Complex Incorporated into a Covalent Organic Framework

AbstractPt(II)‐based molecular catalysts stand as a prototypical system in hydrogen evolution reactions (HER) owing to their consistently elevated activity levels. Their integration into heterogeneous systems thus provides an ideal platform to develop catalytic materials with optimal atom economy. In this work, by rational molecular design, we have synthesized a novel two‐dimensional photoactive Covalent Organic Framework (COF), wherein the pore walls host a quinoline‐based α‐diimine ligand serving as a coordination site for anchoring a Pt(II) molecular catalyst. Thorough structural analyses, employing X‐ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT‐IR), diffuse reflectance spectroscopy (DR), coupled with DFT calculations, distinctly confirm the Pt(II) complexation through the coordination site of the α‐diimine ligand. The Pt(II)‐metalated COF exhibits photocatalytic activity with a hydrogen evolution rate reaching up to 1300 μmol g−1 h−1. Nevertheless, the occurrence of platinum nanoparticles in post‐catalysis samples, along with reduced photocatalytic activity in the presence of chloride ions, suggests that Pt(II) anchored into the COF backbone might not be the primary catalytic site.

Computed tomography technologies to measure key structural features of polymeric biomedical implants from bench to bedside.

Implanted polymeric devices, designed to encourage tissue regeneration, require porosity. However, characterizing porosity, which affects many functional device properties, is non-trivial. Computed tomography (CT) is a quick, versatile, and non-destructive way to gain 3D structural information, yet various CT technologies, such as benchtop, preclinical and clinical systems, all have different capabilities. As system capabilities determine the structural information that can be obtained, seamless monitoring of key device features through all stages of clinical translation must be engineered intentionally. Therefore, in this study we tested feasibility of obtaining structural information in pre-clinical systems and high-resolution micro-CT (μCT) under physiological conditions. To overcome the low CT contrast of polymers in hydrated environments, radiopaque nanoparticle contrast agent was incorporated into porous devices. The size of resolved features in porous structures is highly dependent on the resolution (voxel size) of the scan. As the voxel size of the CT scan increased (lower resolution) from 5 to 50 μm, the measured pore size was overestimated, and percentage porosity was underestimated by nearly 50%. With the homogeneous introduction of nanoparticles, changes to device structure could be quantified in the hydrated state, including at high-resolution. Biopolymers had significant structural changes post-hydration, including a mean increase of 130% in pore wall thickness that could potentially impact biological response. By incorporating imaging capabilities into polymeric devices, CT can be a facile way to monitor devices from initial design stages through to clinical translation.

Achieving high strength and low thermal conductivity: Additive manufacturing of mullite lightweight refractory

Complex geometries of mullite lightweight refractory materials with high strength and low thermal conductivity were successfully achieved through additive manufacturing using the direct ink writing technique and fly ash beads coated with alumina sol. In the refractory preparation process, printing ability of the ink was enhanced by adding additives (dispersant and binder). The adjustment of printing parameters, such as pressure, nozzle size, and printing speed, resulted in an enhancement of the refractory structure's accuracy. Compared to the ink with uncoated fly ash beads, the inks with coated fly ash beads show better stability and shear thinning behavior. The compressive strength of the refractories improved significantly. Meanwhile, the thermal conductivity of the refractories kept in a low level. The use of fly ash beads coated with alumina sol in the preparation of porous refractory resulted in the formation of mullite wishers within the pore walls. This created micron-size pores between the whiskers, greatly enhancing the thermal insulation and strength of the porous refractories. The Ashby-Glicksman model was particularly advantageous in predicting the thermal conductivity of the insulation refractories, especially when dealing with a complex pore structure. Therefore, utilizing the direct ink writing technique to produce lightweight refractory materials shows promise in addressing the challenge of creating intricate lightweight refractory parts.

Surface Charge Regulation on the Concave Wall of a Spherical Silica Pore, Impact of the EDL Overlap, Potential Drop in the Stern Region, and Deviation from the Electroneutrality Principle

Surface Charge Regulation on the Concave Wall of a Spherical Silica Pore, Impact of the EDL Overlap, Potential Drop in the Stern Region, and Deviation from the Electroneutrality Principle