Oriented Pore Structure Research Articles

An Innovative Experimental Methodology for Testing Anisotropic Permeabilities of Formation Rocks

Abstract The permeability of reservoir rocks is a typical anisotropic property. Accurate testing and characterization of reservoir in situ anisotropic permeability is crucial for geo-energy applications including geothermal energy extraction, hydrocarbon reservoir development, coalbed methane production, and carbon dioxide geological sequestration. In this work, a novel experimental apparatus was designed to more precisely determine the permeability tensor of reservoir rocks. The device can independently apply stresses in different directions to simulate in situ reservoir stress conditions and reservoir temperatures. The experiment can accurately measure the principal components of the permeability tensor in three directions for rock samples while effectively avoiding experimental errors caused by internal structure damage during disassembly. Using the self-developed apparatus, anisotropic permeability tests were conducted on sandstone, shale, and coal samples. The results show that the three-dimensional permeability of rock samples under in situ reservoir stress conditions is lower than under isotropic stress conditions. However, the variation magnitude of the three-dimensional permeability differs between the three rock types because of lithological differences. This confirms the difference in data between the proposed anisotropic permeability test method and other traditional methods. We also observed that for rocks without distinct oriented internal structures like sandstone, anisotropic permeability is more sensitive to (normal) stress changes. In contrast, for rocks with oriented pore structures such as shale and coal, the degree of anisotropic permeability is less sensitive to (normal) stress changes. The proposed novel anisotropic permeability test method obtains more accurate and realistic data under simulated in situ stress conditions compared with existing methods. It can evaluate rock properties and optimize geothermal or hydrocarbon production well designs to improve production efficiency.

Biodegradable Honeycomb-Mimic Scaffolds Consisting of Nanofibrous Walls.

The scaffold is a porous three-dimensional (3D) material that supports cell growth and tissue regeneration. Such 3D structures should be generated with simple techniques and nontoxic ingredients to mimic bio-environment and facilitate tissue regeneration. In this work, simple but powerful techniques are demonstrated for the fabrication of lamellar and honeycomb-mimic scaffolds with poly(L-lactic acid). The honeycomb-mimic scaffolds with tunable pore size ranging from 70 to 160µm are fabricated by crystal needle-guided thermally induced phase separation in a directional freezing apparatus. The compressive modulus of the honeycomb-mimic scaffold is ≈4 times higher than that of scaffold with randomly oriented pore structure. The fabricated honeycomb-mimic scaffold exhibits a hierarchical structure from nanofibers to micro-/macro-tubular structures. Pre-osteoblast MC3T3-E1 cells cultured on the honeycomb-mimic nanofibrous scaffolds exhibit an enhanced osteoblastic phenotype, with elevated expression levels of osteogenic marker genes, than those on either porous lamellar scaffolds or porous scaffolds with randomly oriented pores. The advanced techniques for the fabrication of the honeycomb-mimic structure may potentially be used for a wide variety of advanced functional materials.

Cell-free chitosan/silk fibroin/bioactive glass scaffolds with radial pore for in situ inductive regeneration of critical-size bone defects

Tissue-engineered is an effective method for repairing critical-size bone defects. The application of bioactive scaffold provides artificial matrix and suitable microenvironment for cell recruitment and extracellular matrix deposition, which can effectively accelerate the process of tissue regeneration. Among various scaffold properties, appropriate pore structure and distribution have been proven to play a crucial role in inducing cell infiltration differentiation and in-situ tissue regeneration. In this study, a chitosan (CS) /silk fibroin (SF) /bioactive glass (BG) composite scaffold with distinctive radially oriented pore structure was constructed. The composite scaffolds had stable physical and chemical properties, a unique pore structure of radial arrangement from the center to the periphery and excellent mechanical properties. In vitro biological studies indicated that the CS/SF/BG scaffold could promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and the expression of related genes due to the wide range of connected pore structures and released active elements. Furthermore, in vivo study showed CS/SF/BG scaffold with radial pores was more conducive to the repair of skull defects in rats with accelerated healing speed during the bone tissue remodeling process. These results demonstrated the developed CS/SF/BG scaffold would be a promising therapeutic strategy for the repair of bone defects regeneration.

Dielectric tunability of 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 porous ceramics with oriented pore structure

Dielectric tunability of 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 porous ceramics with oriented pore structure

Oriented Porous Polymer Scaffolds in Tissue Engineering: A Comprehensive Review of Preparation Strategies and Applications

AbstractThe pursuit of effective therapeutic strategies for tissue damage has prompted extensive scholarly investigations worldwide. Tissue engineering has emerged as a prominent approach, particularly through the utilization of artificial scaffolds that closely resemble the natural extracellular matrix (ECM). These scaffolds exhibit multi‐scale topological structures and surface physicochemical properties, which significantly influence cellular behavior, thereby attracting considerable attention from numerous researchers. This comprehensive review is concentrated on the primary techniques employed in the fabrication of biodegradable polymer scaffolds possessing oriented porous structures, and the most recent advancements in tissue engineering research are presented. Significantly, the profound influence of scaffold surface characteristics is underscored on cellular behavior, elucidating the superiority of oriented pore structures over disordered ones in mimicking the distinctive attributes of the ECM. Enhanced cell adhesion, proliferation, and tissue differentiation represent notable advantages associated with oriented porous scaffolds. Additionally, the critical interplay between scaffold structure, performance, and functionalization is emphasized, highlighting the imperative to optimize the clinical application of tissue engineering scaffolds.

Modified SUZ-4 zeolite with hierarchical stacked structures used as interlayer improving thin-film composite membrane performance for the IPA pervaporation dehydration

SUZ-4 zeolite is a needle-like material with an oriented pore structure that has potential for separation. It is desired to prepare high-performance thin film composite (TFC) membranes via the interfacial polymerization (IP) process after incorporating SUZ-4 zeolite interlayers on macroporous ceramic hollow fibers to compensate for the surface defects. However, the incomplete coverage of the needle-like zeolite for the surface seriously affects the performance of the formed membranes. The spatial confinement property of graphene oxide (GO) was used to modify the SUZ-4 zeolite to the SUZ-4(G) zeolite with hierarchical stacked structures and larger size. SUZ-4(G) zeolite achieved sufficient coverage of the alumina substrate and obtained TFC membranes with good performance for isopropanol (IPA) dehydration under the one-pass IP process with ethylenediamine (EDA) and trimesoyl chloride (TMC). The TFC membrane after further optimization displayed a flux of 3.18 ± 0.1 kg/(m2·h) with a separation factor of 3034 ± 98 (the water concentration in permeate was about 99.7 wt%) applied to pervaporation (PV) dehydration of 90 wt% IPA aqueous solution at 60 °C. Additionally, the novel TFC membrane developed has the potential for further applications due to its good stability.

Porous Poly(l-lactide)/Poly(d-lactide) Blend Film with Enhanced Flexibility and Heat Resistance via Constructing a Regularly Oriented Pore Structure

Porous Poly(<scp>l</scp>-lactide)/Poly(<scp>d</scp>-lactide) Blend Film with Enhanced Flexibility and Heat Resistance via Constructing a Regularly Oriented Pore Structure

Enhanced electrochemical and thermal behavior of lithium-ion batteries with ultrathick electrodes via oriented pores

The increasingly extensive application scale compels the development of lithium-ion batteries toward higher energy densities to eliminate endurance anxiety. Developing ultrathick electrodes to compress the proportion of inactive components is the most direct strategy to improve battery energy densities, although overshadowed by the enthusiasm of searching for new chemistry; however, sluggish ion transport kinetics, especially at high discharge rates, is the main challenge faced by thick electrodes. Here, we demonstrate two variants of oriented pore structures to enable ion fast transport in thick electrodes, and develop a quasi-3D electrochemical-thermal coupled model for lithium-ion batteries based on an open-source computational fluid dynamics platform to investigate their electrochemical and thermal behavior. The results show that the oriented pore electrodes yield an over 2-fold increase in the areal energy density of full-cells at the high discharge rate of 3C, and have a more uniform local distribution of Li ions in both electrolyte and electrodes. Meanwhile, the heat generation rate of battery can be reduced clearly due to their lower ohm resistance. Additionally, a comprehensive critical parameter analysis of oriented pores is performed with the aim of providing a further understanding for ultrathick electrodes that can help maximize the areal energy density of full-cells.

Lightweight chitosan-derived carbon/rGO aerogels loaded with hollow Co1-xNixO nanocubes for superior electromagnetic wave absorption and heat insulation

Designing lightweight electromagnetic (EMW) absorption materials with an ultra-broad effective absorption bandwidth (EAB), strong reflection loss (RL), and low filling level remains a challenging. In this study, an anisotropic chitosan-derived carbon/reduced graphene oxide (rGO) aerogel loaded with hollow ZIF-67 nanocubes (CG3) was constructed via unidirectional freeze-drying, heat treatment, and in situ ZIF-67 growth, followed by chemical etching. The interconnected oriented cell walls, hollow ZIF-67 nanocubes, and heterogeneous carbon/rGO interfaces enhanced EMW absorption as a result perfect impedance matching, multiple scattering, and strong dielectric polarizations. Thus, an outstanding EMW absorption performance with an ultra-broad EAB of 9.5 GHz and a minimal RL (RLmin) of −53.3 dB was achieved for the CG3 aerogel with an ultra-low filling ratio (5.5 wt%). Further, to integrate strong EMW absorption and heat insulation abilities, the hollow ZIF-67 nanocubes loaded on the carbon/rGO aerogel were converted into hollow Co1-xNixO nanocubes (CG4) via a cation exchange reaction and annealing treatment in air. Owing to the oriented pore structure, the CG4 aerogel exhibited obviously anisotropic EMW absorption and heat insulation. When the CG4 aerogel was cut along the longitudinal section parallel to the direction of ice crystal growth (CG4-L), a tubelike porous structure was revealed, and this endowed the aerogel with the highest EMW absorption (EAB = 8.7 GHz, RLmin = -52.3 dB) and thermal insulation (thermal conductivity = 0.057 W m−1 K−1) performance because of the extended EMW transmission and thermal transfer pathways. Thus, this work offers an important design strategy for obtaining high-performance thermally insulating, EMW-absorbing composites.

An All-Natural Wood-Inspired Aerogel.

The oriented pore structure of wood endows it with a variety of outstanding properties, among which the low thermal conductivity has attracted researchers to develop wood-like aerogels as excellent thermal insulation materials. However, the increasing demands of environmental protection have put forward new and strict requirements for the sustainability of aerogels. Here, we report an all-natural wood-inspired aerogel consisting of all-natural ingredients and develop a method to activate the surface-inert wood particles to construct the aerogel. The obtained wood-inspired aerogel has channel structure similar to that of natural wood, endowing it with superior thermal insulation properties to most existing commercial sponges. In addition, remarkable fire retardancy and complete biodegradability are integrated. With the above outstanding performances, this sustainable wood-inspired aerogel will be an ideal substitute for the existing commercial thermal insulation materials.

An All‐Natural Wood‐Inspired Aerogel

AbstractThe oriented pore structure of wood endows it with a variety of outstanding properties, among which the low thermal conductivity has attracted researchers to develop wood‐like aerogels as excellent thermal insulation materials. However, the increasing demands of environmental protection have put forward new and strict requirements for the sustainability of aerogels. Here, we report an all‐natural wood‐inspired aerogel consisting of all‐natural ingredients and develop a method to activate the surface‐inert wood particles to construct the aerogel. The obtained wood‐inspired aerogel has channel structure similar to that of natural wood, endowing it with superior thermal insulation properties to most existing commercial sponges. In addition, remarkable fire retardancy and complete biodegradability are integrated. With the above outstanding performances, this sustainable wood‐inspired aerogel will be an ideal substitute for the existing commercial thermal insulation materials.

Multifunctional NiCo@RGO/SWNTs foam with oriented pore structure for excellent electromagnetic interference shielding

Constructing multifunctional material toward advanced electromagnetic interference (EMI) shielding has become a development trend. Carbon-based foams with excellent EMI shielding performance and structural stability for various environments are being widely studied. Here, an oriented pore structure was assembled with a carbon-based conductive skeleton, consisting of single-walled carbon nanotubes (SWNTs) and two-dimensional reduced graphene oxide (RGO), for facilitating the electromagnetic wave (EMW) to be multilevelly reflected in the confined space. In addition, magnetic NiCo nanoparticles were introduced to further improve the shielding performance by enhancing the magnetic loss. The as-prepared NiCo@RGO/SWNTs foam (NiCo@RSF) exhibited an exceptional EMI shielding effectiveness (SE) of 105 dB at the whole X band (8.2–12.4 GHz) with an ultralow density (0.0135 g cm−3). Moreover, the foam possessed extraordinary heat insulation and flame-retardant properties. Overall, the lightweight multifunctional foam with an oriented pore structure is thus promising for applications in advanced EMI shielding and other specific areas.

Anisotropic and Lightweight Carbon/Graphene Composite Aerogels for Efficient Thermal Insulation and Electromagnetic Interference Shielding.

High-performance and lightweight carbon aerogels (CAs) have attracted considerable attention in various fields such as electrochemistry, catalysis, adsorption, energy storage, and so on. However, finding an environmentally friendly and efficient preparation method and achieving a controllable performance of CAs are still a challenge. Herein, a series of anisotropic carbon/graphene composite aerogels were synthesized by unidirectional freezing of polyamic acid ammonium salt/graphene oxide (PAS/GO) suspension followed by lyophilization, thermal imidization, and carbonization. The prepared aerogels presented a tubular pore structure oriented along the freezing direction. The GO dispersed in the polymer matrix reinforced the skeleton of aerogels, which significantly inhibited the volume shrinkage during the preparation process, thus giving low densities of 0.074-0.185 g cm-3. In addition, the oriented pore structure endowed the composite aerogels with obviously anisotropic heat insulation performance. The radial thermal conductivity was as low as 0.038 W m-1 K-1 at the density of 0.074 g cm-3. When the initial content of GO rose to 20 phr, the resultant aerogels exhibited a high electrical conductivity of about 0.77 S cm-1 in the radial direction and the electromagnetic interference shielding effectiveness (EMI SE) reached 54.6 dB at the same time. Therefore, this study provided a facile and environmentally friendly method to prepare lightweight and anisotropic carbon aerogels.

3–1-type PZT-based porous ceramic and composites with highly oriented pore structure for acoustic applications

3–1-type PZT-based porous ceramic and composites with highly oriented pore structure for acoustic applications

Porous NiCu alloy cathode with oriented pore structure for hydrogen evolution reaction by freeze casting

Porous NiCu alloy with oriented pore structure was successfully prepared by freeze casting method with Ni powders and Cu powders as the source materials, and water as the solvent. The pore structure of porous NiCu alloy was analyzed, finding that the porous NiCu alloy frozen at lower temperature having thinner wall thickness and narrower pore width. The electrocatalytic performance for hydrogen evolution reaction (HER) in 6 M KOH at room temperature was evaluated by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy techniques. Results show that porous NiCu alloy frozen at − 50 °C exhibits the most excellent electrocatalytic activity for HER.

Preparation of porous carbonized woods impregnated with lauric acid as shape-stable composite phase change materials

Porous carbonized woods (PCWs) were prepared by delignification and carbonization treatment of sycamore woods as encapsulation materials of lauric acid (LA) phase change materials (PCMs). The PCWs exhibited regular oriented pore structure (10–20 μm), high porosity (88.86%), low bulk density (0.15 g/cm3), and large pore volume (5.80 cm3/g), which allowed larger heat storage capacity of LA and lightweight characteristic. LA/PCWs shape-stable composite phase change materials (LA/PCWs ss-CPCMs) showed maximum adsorption ratio of LA (81.1 wt.%). The DSC results indicated that the phase change temperatures and latent heat of LA/PCWs ss-CPCMs were respectively 41.0 °C and 177.9 J/g in melting process, and 38.9 °C and 178.2 J/g in solidification process, respectively. PCWs showed little restrictive effect on the phase change behavior of LA. Non-isothermal crystallization results showed that the activation energy of LA (−333.4 kJ/mol) was higher than that of LA/PDCWs (−170.47 kJ/mol) but the half crystallization time of LA was lower than that of LA/PDCWs, indicating that PCWs significantly increased the nucleation rate of LA but slightly limited its crystal growth. Thermal cycles test, FT-IR and TGA results indicated that the LA/PCWs ss-CPCMs showed excellent thermal reliability, chemical compatibility and thermal stability.

Preparation of graphene aerogel-poly(3,4-ethylenedioxythiophene) conductive composite by using simultaneous co-vaporized vapor phase polymerization

We prepared spherical reduced graphene oxide aerogels (rGOA) through freeze casting and thermal reduction for the fabrication of carbon-conducting polymer composites with excellent electrical and mechanical properties. The rGOA-poly(3,4-ethylenedioxythiophene) (PEDOT) or rGOA-PEDOT-SiO2 composites were prepared by simultaneous co-vaporized vapor phase polymerization (SC-VPP). The rGOA spherical particles, prepared by freeze casting of GO solution, had a radially oriented pore structure at the center of its cross section and increasing density of GO sheet towards its center because the temperature gradient of the droplet of the GO solution rapidly freezes from the water outside the droplet during the process. The morphology of the rGOA-PEDOT-SiO2 composites prepared using SCVPP was more spherical compared to rGOA-PEDOT composites, and the orientation of the cross-pore structure was well-developed. Moreover, micrometer-sized conductive PEDOT-SiO2 hybrid spheres could be formed on the composite’s surface by controlling the amount of FTS oxidant. The rGOA-PEDOT-SiO2 composites showed lower resistance values and higher current densities at the same voltage than rGOA or rGOA-PEDOT composites. This can be attributed to the surface area of the particle’s surface, which is enlarged due to the presence of the microspheres, which can cause the widening of the contact area with the electrode to facilitate better electron migration.

Oriented Arrangement: The Origin of Versatility for Porous Graphene Materials.

Macroscopic porous graphene materials composed of graphene sheets have demonstrated their advantageous aspects in diverse application areas. It is essential to maximize their excellent performances by rationally controlling the sheet arrangement and pore structure. Bulk porous graphene materials with oriented pore structure and arrangement of graphene sheets are prepared by marrying electrolyte-assisted self-assembly and shear-force-induced alignment of graphene oxide sheets, and the super elasticity and anisotropic mechanical, electrical, and thermal properties induced by this unique structure are systematically investigated. Its application in pressure sensing exhibits ultrahigh sensitivity of 313.23 kPa-1 for detecting ultralow pressure variation below 0.5 kPa, and it shows high retention rate for continuously intercepting dye molecules with a high flux of ≈18.7 L m-2 h-1 bar-1 and a dynamic removal rate of 510 mg m-2 h-1 .

Freeze casting of novel porous silicate cement supports using tert-butyl alcohol-water binary crystals as template: Microstructure, strength and permeability

Freeze casting liquid dispersions of solid particles is an effective method for preparing porous composites, thus creating strong and lightweight materials with “designed” microstructures for various applications. This work illuminates that tert-butyl alcohol (TBA)/water (H2O) mutually miscible system can be used as template to prepare aligned porous silicate cement supports with unique pore structures via directional freezing. The resulting pore morphology of porous cement substrates changes from prismatic to needle-like, dendritic, coralline, graininess and lamellar structure with the increasing of TBA-H2O ratio in cement slurry. Pore size distributions (macropores and mesopores) demonstrate the hierarchical pore structure of porous cement. The BET surface area (SBET) of porous cement support increases with the decreasing TBA content in cement slurry, until the pore forming agent was pure water. Porous cement that are fabricated from mixed slurries with relatively high TBA-H2O ratio show better mechanical strength. Porous cement support prepared from cement slurry with 90wt% TBA exhibits the best permeation performance due to its well-distributed and oriented pore structure. These findings demonstrate how an aligned and hierarchical porous inorganic support with desirable properties can be prepared, under mild conditions, with the combination of advanced casting technique and most ancient construction material on earth.

Porous Cu foams with oriented pore structure by freeze casting

In this study, Cu foams with oriented pore structure were successfully prepared by freeze casting using Cu powders as the raw materials. The effect of cooling temperature on the microstructure and compressive stress were discussed. Results show that the pore size and porosity decrease with lowering the frozen temperatures. Furthermore, the Cu foam with pores parallel to the loading axis has larger compressive strength than that normal to the loading axis under the same strain. The 0.2% yield strength decreases from 25.4 to 12.6MPa and 23.7 to 8.6MPa, respectively in the direction parallel or normal to the freezing direction when the porosity increases from 65% to 80%.