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Activated carbon has an excellent porous structure and is considered a promising adsorbent and electrode material. In this study, activated carbon fibers (ACFs) with abundant microporous structures, derived from natural cotton fibers, were successfully synthesized at a certain temperature in an Ar atmosphere and then activated with KOH. The obtained ACFs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental analysis, nitrogen and carbon dioxide adsorption-desorption analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption measurement. The obtained ACFs showed high porous qualities and had a surface area from 673 to 1597 m2/g and a pore volume from 0.33 to 0.79 cm3/g. The CO2 capture capacities of prepared ACFs were measured and the maximum capture capacity for CO2 up to 6.9 mmol/g or 4.6 mmol/g could be achieved at 0 °C or 25 °C and 1 standard atmospheric pressure (1 atm). Furthermore, the electrochemical capacitive properties of as-prepared ACFs in KOH aqueous electrolyte were also studied. It is important to note that the pore volume of the pores below 0.90 nm plays key roles to determine both the CO2 capture ability and the electrochemical capacitance. This study provides guidance for designing porous carbon materials with high CO2 capture capacity or excellent capacitance performance.

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Thermal damage due to microstructure changes will occur in propellants under thermal stimulation. It can significantly affect the sensitization, combustion, and other properties of the propellant, which, in turn, affects the impact safety of the solid propellant rocket engine. A new component which uniformly heats the sample was designed to conduct the Lagrange test and EFP impact test at different temperatures. The thermal decomposition and damage characteristics of the propellant during the heating process were quantitatively analyzed. Additionally, the effects of ambient temperature on impact initiation and detonation growth of the high-energy propellant were elucidated at a mesoscopic level. The results showed that the porosity of the specimen increased by 0.89% under the thermomechanical mechanism, which was mainly characterized by interfacial de-bonding between the AP and the binder. The increase in thermal damage changed the hot spot reaction rate and significantly affected the growth process of propellant impact initiation. A method was proposed to systematically calibrate the reaction rate model for the propellant at different temperatures. The theoretical model parameters of the high-energy propellant at two typical temperatures were calibrated in this way. The critical shell thicknesses computed using LS-DYNA, which, for 20 and 70 °C, were obtained as 15 and 20 mm, respectively.

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A high-strength aerogel with a 3D hierarchically macro-meso-microporous structure (HPS-aerogel) was designed based on biological macromolecules of chitin and chitosan. The macropores can be created within HPS-aerogel after CaCO3 removal, and meso-micropores resulting from water sublimation during freeze-drying. The macro-meso-microporous structure endowed HPS-aerogel with high porosity, good mechanical properties, and excellent compression strength (1472 kPa at strain of 80 %). The HPS-aerogel exposed many adsorption sites and was used as an adsorbent to simultaneously remove Cu(II) and Congo red (CR) from water for the first time. The adsorption capability for Cu(II) and CR was 59.21 mg/g and 2074 mg/g at 303 K, respectively, and the adsorption processes matched Pseudo-second-order and Langmuir models with spontaneous and endothermic nature. Additionally, HPS-aerogel showed good anti-interference ability for coexisting pollutant. Importantly, HPS-aerogel exhibited an effective fixed-bed column adsorption performance for dynamic Cu(II) and CR with superior reusability and stability. Furthermore, HPS-aerogel showed outstanding adsorption efficiencies for Cu(II) and CR in real samples. The main adsorption mechanism for Cu(II) was attributed to the electrostatic attraction and chelation, and which was electrostatic attraction, Schiff base, and hydrogen bonding for CR. Therefore, HPS-aerogel should to be a promising adsorbent for removing both heavy-metal ions and dyes from wastewater.

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Porous carbons have been widely applied for capacitive energy storage, yet usually suffer from insufficient rate performance because of the sluggish ion transport kinetics in deep and multi-branched pores. Herein, we fabricated an interconnected microporous capacitive carbon (IMCC) by growing D (+)-glucosamine on bacterial cellulose (BC) nanofibers scaffold, followed by carbonization and activation. The BC nanofibers acted as a sacrificial template during pre-carbonization, facilitating the subsequent KOH permeation and homogeneous activation. By taking advantage of the interconnected microporous structure, the IMCC delivers a high capacitance of 302 F g-1 at 1 A g-1 and an excellent rate capability of 165 F g-1 at 100 A g-1 for aqueous supercapacitor, demonstrating its fast ion transport capability. Impressively, it also shows a superior gravimetric capacity of 177 mAh g-1 at 0.5 A g-1 and remains a high value of 72 mAh g-1 at 20 A g-1 as a cathode material for Zn-ion hybrid capacitor. This facile and cost-effective design strategy exhibits a great potential to construct carbohydrates-derived interconnected microporous carbon materials for high-rate energy storage.

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Polyamide 66 microporous membranes were prepared by cold non-solvent-induced phase separation using polyamide 66-formic acid-propylene carbonate as a ternary membrane-forming system. The formed membranes exhibited a special bicontinuous structure consisting of interglued spherical crystals or interlocked bundles of microcrystalline aggregates. The variation of the microporous structure under the influence of preparation conditions, solvent, aging time, and polymer concentration affects the comprehensive performance of the membranes. For example, the cold-induced operation and the use of different membrane-forming solvents contributed to the crystallization of polyamide 66, resulting in an increased contact angle of polyamide 66 membranes, obtaining a high resistance to contamination of up to 73.5%. Moreover, the formed membranes still have high mechanical strength.

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Hierarchically porous metal-organic frameworks (HP-MOFs) are promising in many applications. However, most previous studies focus on HP-MOFs with two kinds of pore structures. Herein, a strategy for efficient construction of HP-MOFs possessing macro-meso-micropores using template-assisted spray drying followed by etching process is proposed. Taking ZIF-8 as an example, using polystyrene (PS) templates, the complete HP-ZIF-8 with all the three categories of pores can be easily fabricated. The close arrangement of intrinsic microporous nanosized ZIF-8 (N-ZIF-8) in the spray drying process results in the creation of mesopores, while the macropores are further generated after the removal of PS templates. The structures of macropores and mesopores can be easily adjusted by altering the size and proportion of PS and the size of N-ZIF-8, respectively. Furthermore, this method is extended to the preparation of HP-HKUST-1. As a proof-of-concept, HP-ZIF-8 displays excellent catalytic properties in Knoevenagel reaction owing to its unique pore features. Compared with conventional microsized ZIF-8 (M-ZIF-8) with similar size, HP-ZIF-8 achieves the significantly increased conversion of benzaldehyde from 55% to 100% within 3 h, and shows better recycling performance than N-ZIF-8.

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This paper presents the results of a computer analysis of the effect of activation process temperature on the development of the microporous structure of activated carbon derived from the leaves of common polypody (Polypodium vulgare) via chemical activation with phosphoric acid (H3PO4) at activation temperatures of 700, 800, and 900 °C. An unconventional approach to porous structure analysis, using the new numerical clustering-based adsorption analysis (LBET) method together with the implemented unique gas state equation, was used in this study. The LBET method is based on unique mathematical models that take into account, in addition to surface heterogeneity, the possibility of molecule clusters branching and the geometric and energy limitations of adsorbate cluster formation. It enabled us to determine a set of parameters comprehensively and reliably describing the porous structure of carbon material on the basis of the determined adsorption isotherm. Porous structure analyses using the LBET method were based on nitrogen (N2), carbon dioxide (CO2), and methane (CH4) adsorption isotherms determined for individual activated carbon. The analyses carried out showed the highest CO2 adsorption capacity for activated carbon obtained was at an activation temperature of 900 °C, a value only slightly higher than that obtained for activated carbon prepared at 700 °C, but the values of geometrical parameters determined for these activated carbons showed significant differences. The results of the analyses obtained with the LBET method were also compared with the results of iodine number analysis and the results obtained with the Brunauer-Emmett-Teller (BET), Dubinin-Radushkevich (DR), and quenched solid density functional theory (QSDFT) methods, demonstrating their complementarity.

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Highly functional macromolecules with a well-defined architecture are the key to designing efficient and smart materials, and these polymeric systems can be tailored for specific applications in a diverse range of fields. Herein, the formation of a new liquid crystalline polymeric network based on the crosslinking of dendrimeric entities by the CuI-catalyzed variant of the Huisgen 1,3-dipolar cycloaddition of azides and alkynes to afford 1,2,3-triazoles is reported. The polymeric material obtained in this way is easy to process and exhibits a variety of properties, which include mesomorphism, viscoelastic behavior, and thermal contraction. The porous microstructure of the polymer network determines its capability to absorb solvent molecules and to encapsulate small molecules, like organic dyes, which can be released easily afterwards. Moreover, all these properties may be easily tuned by modifying the chemical structure of the constituent dendrimers, which makes this system a very interesting one for a number of applications.

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This paper addresses the problem of improving electrochemical energy storage with electrode materials obtained from common raw ingredients in a facile synthesis. In this study, we present a simple, one-pot route of synthesizing microporous carbon via a very fast reaction of sucrose and graphene (carbon source), chitosan (carbon and nitrogen source), and H3PO4. Porous carbons were successfully produced during high temperature carbonization, using nitrogen as a shielding gas. Samples were characterized using X-ray powder diffractometry, elemental analysis, N2 adsorption-desorption measurements, scanning electron microscopy, and Raman spectroscopy. The developed carbon material possessed a high surface area, up to 1313 m2 g-1, with no chemical or physical activators used in the process. The structural parameters of the microporous carbons varied depending on the ratio of reagents and mass composition. Samples were prepared both with and without chitosan. The present synthesis route has the advantages of being a single-step approach and only involving low-cost and environmentally friendly sources of carbon. More importantly, microporous carbon was prepared without any activators and potentially offers great application in supercapacitors. Cyclic voltammetry and constant current charge-discharge tests show that sucrose-based porous carbons show excellent electrochemical performance with a specific capacitance of up to 143 F g-1 at a current density of 1 A g-1 in a 6 M KOH electrolyte.

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Adsorption of low-density lipoprotein from plasma is vital for the treatment of dyslipidemia. Appropriate adsorbent material for efficient and selective adsorption of low-density lipoprotein is highly desired. In this work, we developed pollens-derived magnetic porous particles as adsorbents for this purpose. The natural pollen grains were modified to obtain high surface porosity, a large inner cavity, magnet responsiveness, and specific wettability. The resultant particles exhibited satisfying performance in the adsorption of a series of oils and organic solvents out of water. Besides, the particles were directly utilized to the adsorption of low-density lipoprotein in plasma, which showed high selectivity, and achieved an outstanding adsorption capacity as high as 34.9% within 2 h. Moreover, their salient biocompatibility was demonstrated through simulative hemoperfusion experiments. These features, together with its abundant source and facile fabrication, makes the pollens-derived magnetic porous particles excellent candidate for low-density lipoprotein -apheresis and water treatment applications.

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Chemical architectures with an ordered porous backbone and high charge transfer are significant for fiber-shaped supercapacitors (FSCs). However, owing to the sluggish ion kinetic diffusion and storage in compacted fibers, achieving high energy density remains a challenge. An innovative magnetothermal microfluidic method is now proposed to design hierarchical carbon polyhedrons/holey graphene (CP/HG) core-shell microfibers. Owing to highly magnetothermal etching and microfluidic reactions, the CP/HG fibers maintain an open inner-linked ionic pathway, large specific surface area, and moderate nitrogen active site, facilitating more rapid ionic dynamic transportation and accommodation. The CP/HG FSCs show an ultrahigh energy density (335.8 µWh cm-2 ) and large areal capacitance (2760 mF cm-2 ). A self-powered endurance application with the integration of chip-based FSCs is designed to profoundly drive the durable motions of an electric car and walking robot.

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A series of amorphous melamine-based polymer networks synthesized by Schiff base chemistry (SNW) were successfully prepared by varying the strut length. The pore structure was analyzed by gas adsorption and positron annihilation methods. Positron lifetime measurements indicate the existence of ultramicropores and also larger mesopores in the SNW materials. The sizes of micropores and mesopores are almost the same in these samples, which are about 0.7 and 16.5 nm, respectively. The relative number of micropores increases in the order of SNW-1 < SNW-2 < SNW-3, while the number of mesopores increases in the reverse order. N2 adsorption/desorption measurements also reveal micropores and mesopores in these materials. However, it gives an underestimation of the micropore volume. Benefiting from the abundant nitrogen content and high microporosity, the SNW materials exhibit exceptionally high CO2 capture ability, which reaches a maximum value of 18.3 wt % in SNW-3 at 273 K and 1 bar, followed by SNW-2 and SNW-1. This order is exactly the same as the order of micropore volume revealed by positron annihilation measurement, suggesting that micropores play a crucial role in the CO2 uptake. Our results show that positron can provide more precise information about the structure of micropores and thus can offer an accurate prediction for the adsorption capacity of complex porous materials.

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BACKGROUND: It has been reported that the microporous structure of calcium phosphate (CaP) ceramics is important to osteoconduction. Bone morphogenetic protein-2 (BMP-2) has been shown to be a promising alternative to bone grafting and a therapeutic agent promoting bone regeneration when delivered locally. The aim of this study was to evaluate the effects of micro-porosity within beta-tricalcium phosphate (ß-TCP) cylinders and local BMP-2 administration on ß-TCP resorption and new bone formation. METHODS: Bilateral cylindrical bone defects were created in rabbit distal femora, and the defects were filled with ß-TCP. Rabbits were divided into 3 groups; defects were filled with a ß-TCP cylinder with a total of approximately 60% porosity (Group A: 13.4% micro- and 46.9% macropore, Group B: 38.5% micro- and 20.3% macropore, Group C: the same micro- and macro-porosity as in group B supplemented with BMP-2). Rabbits were sacrificed 4, 8, 12, and 24 weeks postoperatively. RESULTS: The number of TRAP-positive cells and new bone formation in group B were significantly greater than those in group A at every period. The amount of residual ß-TCP in group C was less than that in group B at all time periods, resulting in significantly more new bone formation in group C at 8 and 12 weeks. The number of TRAP-positive cells in group C was maximum at 4 weeks. CONCLUSIONS: These results suggest that the amount of submicron microporous structure and local BMP-2 administration accelerated both osteoclastic resorption of ß-TCP and new bone formation, probably through a coupling-like phenomenon between resorption and new bone formation.

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Highly microporous carbon material with nitrogen doping has been synthesized via a facile one-step approach by employing natural biowaste miscellaneous wood fibers derived hydrochar as precursor and melamine as nitrogen source respectively. The added melamine not only results in the incorporation of some nitrogen into the carbon framework but also increases the specific surface area of carbon material. Such resultant N-doped microporous carbon possesses the functionalized nitrogen doping (1.75 at. %), a large specific surface area (∼1807 m2 g-1) and abundant highly interconnected micropores. Benefiting from the synergistic effect of high specific surface area, well-developed pore size distribution and functionalized groups, this carbon material delivers a high specific capacitance of 345 F g-1 at 0.5 A g-1, an excellent capacitance retention with 270 F g-1 at up to 30 A g-1, and a remarkable cycle ability with 91.3% retention after 10,000 cycles at 5.0 A g-1. Based on it, the as-developed flexible symmetric solid-state supercapacitor delivers a high energy density of 7.92 W h kg-1 at the power density of 250 W kg-1. Evidently, this work provides a facile and cost-effective route for functionalized natural biowaste-based carbon materials and further opens up a way for highly value-added recycling of biowaste-like materials.

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Electronic skin are devices that mimic the functionalities of human skin, which require high sensitivity, large dynamic range, high spatial uniformity, low-cost and large-area processability, and the capacity to differentiate various external inputs. We herein introduce a versatile droplet-based microfluidic-assisted emulsion self-assembly process to generate three-dimensional microstructure-based high-performance capacitive and piezoresistive pressure sensors for electronic skin applications. Our technique can generate uniformly sized micropores that are self-assembled in an orderly close-packed manner over a large area, which results in high spatial uniformity. The size of the micropores can easily be tuned from 100 to 500 µm, through which sensitivity and dynamic range were controlled as high as 0.86 kPa-1 and up to 100 kPa. Our device can be printed on curvilinear surfaces and be molded into various shapes. We furthermore demonstrate that by simultaneously utilizing capacitive and piezoresistive pressure sensors, we can distinguish between pressure and temperature, or between pressure and proximity. These demonstrations make our process and sensors highly useful for a wide variety of electronic skin applications.

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Various 3-dimensional C/CeO2 hollow nanostructure frameworks (3D C/CeO2 HNFs) were synthesized by using a polymer blowing process that is accelerated by adding a certain amount of cerium nitrate. Polyvinylpyrrolidone was used as the polymer. The resulting HNFs were characterized by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. The HNFs possess a large specific surface area, and the CeO2 nanocrystals consist of a single phase. The HNFs display intrinsic peroxidase-like activity and can catalyze the oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine in the presence of H2O2 to produce a blue product. The method was applied to the quantification of H2O2 with a 5.2 nM detection limit. The analytical range is from 10 nM to 1 µM. Graphical abstract Schematic of the preparation of a 3-dimensional C/CeO2 hollow nanostructure framework by a polyvinylpyrrolidone-blowing process accelerated by Ce(NO3)3. They were applied to H2O2 detection by catalyzing the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) to the oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) to produce blue-color reaction.

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The paper presents the results of research devoted to reliability evaluation of the analysis of results of the porous structure of activated carbons based on incomplete nitrogen adsorption isotherms using the BET, t-plot, and NLDFT methods, as well as the LBET method comprising the unique numerical fast multivariant procedure of adsorption system identification. The research involved the application of the nitrogen adsorption isotherms obtained for five samples of activated carbons produced from waste materials of organic origin by way of chemical activation with potassium hydroxide, sodium hydroxide, and potassium carbonate with the use of microwave heating. The analyses performed pointed to a good correlation between the results obtained using the BET, t-plot, NLDFT, and LBET methods. Moreover, the parameters of the porous structure determined using these methods based on incomplete adsorption isotherms of nitrogen are in fact as reliable as these methods allow.

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While several scaffolds have been proposed for skeletal muscle regeneration, multiscale hierarchical scaffolds with the complexity of extracellular matrix (ECM) haven't been engineered successfully. By precise control over nano- and microscale features, comprehensive understanding of the effect of multiple factors on skeletal muscle regeneration can be derived. In this study, we engineered carbon-based scaffolds with hierarchical nano- and microscale architecture with controlled physico-chemical properties. More specifically, we built multiscale hierarchy by growing carbon nanotube (CNT) carpets on two types of scaffolds, namely, interconnected microporous carbon foams and aligned carbon fiber mats. Nanostructured CNT carpets offered fine control over nano-roughness and wettability facilitating myoblast adhesion, growth and differentiation into myocytes. However, microporous foam architecture failed to promote their fusion into multinucleated myotubes. On the other hand, aligned fibrous architecture stimulated formation of multinucleated myotubes. Most importantly, nanostructured CNT carpets interfaced with microscale aligned fibrous architecture significantly enhanced myocyte fusion into multinucleated mature myotubes highlighting synergy between nanoscale surface features and micro-/macroscale aligned fibrous architecture in the process of myogenesis. STATEMENT OF SIGNIFICANCE: Due to limited regenerative potential of skeletal muscle, strategies stimulating regeneration of functional muscles are important. These strategies are aimed at promoting differentiation of progenitor cells (myoblasts) into multinucleated myotubes, a key initial step in functional muscle regeneration. Recent tissue engineering approaches utilize various scaffolds ranging from decellularized matrices to aligned biomaterial scaffolds. Although, majority of them have focused on nano- or microscale organization, a systematic approach to build the multiscale hierarchy into these scaffolds is lacking. Here, we engineered multiscale hierarchy into carbon-based materials and demonstrated that the nanoscale features govern the differentiation of individual myoblasts into myocytes whereas microscale alignment cues orchestrate fusion of multiple myocytes into multinucleated myotubes underlining the importance of multiscale hierarchy in enhancing coordinated tissue regeneration.

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Phase separation in plasticized cellulose triacetate (CTA) films is investigated to produce a microporous film that can be used in optical devices. Hot-stretched CTA films containing diisodecyl adipate (DIDA) show negative orientation birefringence similar to the hot-stretched pure CTA. After extracting DIDA from the stretched films by immersion into an organic solvent, however, the films exhibit positive birefringence. Moreover, the magnitude of the birefringence increases with the wavelength, known as extraordinary dispersion, which is an essential property in the preparation of an ideal quarter-wave plate. Numerous ellipsoidal pores with micro-scale were detected in the film after the immersion, indicating that DIDA were segregated and formed ellipsoidal domains in the CTA matrix during annealing and stretching. These results indicate that extraordinary wavelength dispersion is given by the combinations of orientation birefringence from CTA and form birefringence from micropores. Furthermore, it was found that annealing time and stretching condition affect the phase separation as well as the shape and size of pores.

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Objective To analyze the influence of microporous parameters on mechanical behavior of bone tissue engineered-scaffolds, and provide references for optimizing the microporous structure design. Methods The finite element models of scaffolds with microporous structures were established by using ANYSYS software. The relationships between porosity and maximum equivalent stress as well as maximum total deformation were calculated. The effects of microporous spacing and diameter on maximum equivalent stress, maximum total deformation and internal strain were compared and analyzed. Results The influence rule of microporous spacing in x and y direction was consistent. With the increase of microporous spacing from 0.6 mm to 2.0 mm, the maximum equivalent stress reduced from 63.1 MPa to 46.3 MPa, the maximum total deformation reduced from 23.8 μm to 21.8 μm, and the proportion of the best strain range increased from 80% to 84%. However, with the increase of microporous spacing in z direction, the maximum equivalent stress increased from 38.3 MPa to 47.8 MPa, the maximum total deformation increased from 20. 8 μm to 22.8 μm, and the proportion of the best strain range fluctuated within the range of 82%-85%. With the increase of microporous diameter in x and y direction from 0.1 mm to 1.0 mm, the maximum equivalent stress increased from 32.4 MPa to 78.4 MPa, the maximum total deformation increased from 19.9 μm to 38.2 μm, and the proportion of the best strain range reduced from 90% to 53%. With the increase of microporous diameter in z direction, the maximum equivalent stress reduced from 58.8 MPa to 37.9 MPa, the maximum total deformation increased from 23.3 μm to 25.9 μm, and the proportion of the best strain range increased from 82% to 87%. Conclusions The greater the porosity and the proportion of the best strain range, the smaller maximum equivalent stress and maximum total deformation would be, the scaffolds would have the better biological and mechanical properties. These results have reference values for design and optimization of scaffold structure.