Porous Microspheres Research Articles

Ionic liquid/covalent organic framework/silica composite material: Green synthesis and chromatographic evaluation

BackgroundDue to their large surface area and distinctive adsorption affinity, covalent organic frameworks (COFs) appear to be good candidates as liquid chromatographic separation materials with good application prospect. The development of COF materials in chromatographic science is currently in an exploratory stage. Especially, the practicability of COF@silica composite materials as liquid chromatographic stationary phases needs further exploration. Reasonably integrating a functional component such as ionic liquid (IL) into the COF@silica composite materials may provide customized functionality to achieve the purpose of synthesizing multi-functional COF based stationary phases. ResultsIn this study, an IL modified COF bonded silica composite material (IL-COF@SiO2) was successfully synthesized by using an environmentally friendly deep eutectic solvent as the reaction medium instead of the frequently-used organic solvent. The synthesized IL-COF@SiO2 composite material combines the excellent separation ability of COF and the excellent mass transfer function of spherical porous silica microsphere, and meanwhile, the introduction of IL endows COF@SiO2 with preferable separation performance. The slurry-packed IL-COF@SiO2 liquid chromatographic column could be applied to effectively separate hydrophobic and hydrophilic compounds with preferable separation selectivity and high column efficiency. By investigating the retention behavior and influencing factors, a mixed-mode retention mechanism was found. Multiple interaction forces endow the IL-COF@SiO2 with a hydrophilic-hydrophobic balance performance, demonstrating a good application prospect as a versatile liquid chromatographic separation material. SignificanceIn this study, a new strategy is proposed for greenly synthesizing a novel IL-COF@SiO2 composite material under mild conditions, which expands the potential application of COF materials in chromatographic science. One particular point to note is that the reaction medium in each step of the preparation process is low toxic and degradable deep eutectic solvent, which conforms to the concept of green chemistry.

Robust silicone rubber with high transparency by loading with porous hollow glass microsphere

Robust silicone rubber with high transparency by loading with porous hollow glass microsphere

Application of Bimetallic Heterojunction Nanoparticle-Based Multishelled Porous Hollow Microspheres as a Two-in-One Inorganic UV Filter

Application of Bimetallic Heterojunction Nanoparticle-Based Multishelled Porous Hollow Microspheres as a Two-in-One Inorganic UV Filter

Rational design of size-controlled spongy porous carbon microspheres with wide-frequency microwave absorption properties

Porous carbon materials have garnered significant attention due to their effective microwave absorption properties. However, the design and preparation of precisely size-controlled porous carbon materials is still a great challenge. Spongy porous carbon microspheres (SPCMs) with adjustable size and uniform particles were successfully synthesized for large-scale production. This synthesis method employed affordable polymethyl methacrylate (PMMA) microspheres as sacrificial templates and phenolic resin oligomers as carbon sources. In addition to size considerations, different carbonization temperatures exert substantial influence on the complex dielectric constant and microwave absorption characteristics. SPCMs samples, characterized by a size of 5 μm and carbonization temperature of 700 °C, exhibited exceptional microwave absorption performance, despite a loading of only 10 wt%. The minimum reflection loss (RLmin) for the matched 2.6 mm thick sample reached −68.2 dB at 15.0 GHz, and the effective absorption bandwidth (EAB) for the matched 2.9 mm thick sample spanned 7.5 GHz. The outstanding microwave absorption capabilities of SPCMs can be attributed to their continuous porous structure, well-suited impedance matching, appropriate conductivity, and abundant interfacial polarization. This work serves as a crucial guide for the development of highly efficient microwave absorbers characterized by thin profiles, lightweight composition, strong absorption characteristics, and a wide EAB.

Hierarchical porous honeycomb microspheres assembled by MoS2 nanocrystals-embedded carbon nanosheets for high-performance lithium storage

Hierarchical porous honeycomb microspheres assembled by MoS2 nanocrystals-embedded carbon nanosheets are synthesized by constructing polystyrene (PS) sphere-embedded Mo-polydopamine organic/inorganic hybrid microspheres, followed by carbonization and sulfuration. The as-prepared composite is systematically studied by various material characterization techniques. It is found that the diameters of the microspheres and honeycomb pores are 3–5 μm and 200 nm. The specific surface area reaches 150.8 m2 g−1. MoS2@honeycomb carbon microsphere anode can achieve outstanding rate performance (237 mAh g−1 at 10 A g−1), high specific capacity and stable long-term cycling performance (reversible capacity of 1199 mAh g−1 at 0.1 A g−1 after 120 cycles, 599 mAh g−1 at 2 A g−1 after 300 cycles with capacity decay rate of 0.07 % per cycle, 495 mAh g−1 at 5 A g−1 after 500 cycles). The high reversible capacity is mainly derived from conversion reaction of MoS2 and lithiation reaction of S, as revealed by the analyses on the rate discharge curves. Kinetic measurements and ex-situ characterization further demonstrate the fast and stable Li+ diffusion, low impedance, strong capacitive effect and robust composite structure. The assembled full cell exhibits a reversible capacity of 209.7 mAh g−1 after 1880 cycles at 5 A g−1 and can power a red LED lamp. Overall, the excellent lithium storage performance manifests the significant potential of this MoS2 composite in high-performance lithium-ion batteries.

3D porous flower-like MoS2 grows on carbon cloth and used as anode material for lithium-ion batteries

In this paper, after hydrothermal reaction, 3D porous flower-like 2H-MoS2 microspheres with size distribution of 400–500 nm were uniformly loaded on carbon cloth (CC) fibers to obtain CC/MoS2 composite. As an anode material for LIBs, the obtained CC/MoS2 composite delivers an initial discharge/charge specific capacities of 1872/1680 mAh g−1 at 0.1 A g−1, with the corresponding Coulomb efficiency is as high as 89.7%. Moreover, combine the advantages of CC and MoS2, excellent cycle stability with 1060 mAh g−1 (0.5 A g−1 for 200 cycles) has been obtained.

Enhanced performance of porous carbon microspheres from bamboo fiber for supercapacitors through acid-assisted hydrothermal carbonization

Porous carbon microspheres with a regular spherical shape were prepared from bamboo pulp fiber through the hydrothermal carbonization process with the assistance of hydrochloric acid and phosphoric acid. It was observed that a higher concentration of hydrochloric acid resulted in increased yields of carbon microspheres with porous surfaces compared to phosphoric acid, and the specific surface area was reached 923.9 m2/g after Na2CO3 activation. The resulting PCS-Cl-0.1 electrode exhibits a high specific capacitance of 292.8F/g at 0.2 A/g and excellent rate performance. This work demonstrates the effectiveness of acid-assisted hydrothermal carbonization in controlling the morphology and enhancing the electrochemical performance of carbon microspheres.

Development of an innovative ethanol sensing sensor platform based on the construction of Au modified 3D porous ZnO hollow microspheres

The practical production of gas sensor devices poses a significant challenge in terms of designing electronic devices that possess the advantages of a simplistic structure and can be easily and conveniently manufactured through batch processing. Hence, a simple architecture is important in creating new type of gas sensor that could realize experimental purposes in real-life situations. Porous zinc oxide hollow microspheres (ZnO HMS) sensing materials were successfully synthesized via hydrothermal process. The detection of ultra-low gas concentrations, such as 100 ppb ethanol, was achieved using a novel ZnO HMS modified with Au. The ethanol sensing perform of the 1.0 wt%Au-ZnO is 7.7 times and 1.7 times higher than that of the ZnO HMS and 0.5 wt%Au-ZnO. Furthermore, even at a low concentration of 100 ppb, a good sensing response of 1.476 is acquired. Also, we found the low theoretical detection limitation of the 1.0 wt%Au-ZnO was 25.1 ppb.

3D printed composites achieve broadband electromagnetic wave absorption by introducing carbon black/carbonyl iron powder porous hollow microspheres

In this paper, carbon black (CB) and carbonyl iron powder (CIP) were successfully combined by solvent evaporation method to prepare CB-CIP porous hollow microspheres and used as reinforcement to prepare electromagnetic wave absorbing composites by 3D printing method. The effects of CB addition on the structure of the composite microspheres and the wave absorption performance were investigated. It is shown that the surfaces of hollow microspheres have many heterogeneous interfaces and pore defects, which can significantly enhance the polarization loss capability. The CB and CIP particles on the surfaces of hollow microspheres are intertwined, which makes the magnetic loss and dielectric loss form a synergistic absorption effect and enhance the microwave absorption capacity of the composite. The maximum reflection loss of sample CB/PLA-3 reaches –47.34 dB at a thickness of 2.5 mm, and the EAB is 4.56 GHz. The EAB reaches a maximum of 5.20 GHz at a thickness of 2 mm. The RCS simulation results of CB/PLA-3 at 11 GHz show that most of the RCS values of the samples are below −20 dBm2 in the range of –90° < Theta < 90°, indicating that the CB/PLA-3 samples has the capability of wide-angle microwave absorption. This paper provides an effective method for the design and preparation of broadband efficient absorbing materials.

Preparation of porous silica microspheres using silica nanoparticles with different morphologies and their properties as catalyst carriers

Preparation of porous silica microspheres using silica nanoparticles with different morphologies and their properties as catalyst carriers

Simultaneous Cr(VI) reduction and Cr(III) sequestration in a wide pH range by using magnetic chitosan-based biopolymer

The simultaneous reduction of Cr(VI) and sequestration of the resulting Cr(III) in one process is highly desirable as a cost-effective and environmental-friendly approach for the decontamination of Cr(VI)-polluted wastewater. However, most of the existing adsorptive materials are only effective in low pH environments (pH = 1–3), severely restricting the adsorption efficiency and cost effectiveness. Herein, we proposed a chitosan-based magnetic porous microsphere (PPy@PMCS) for simultaneous Cr(VI) reduction and Cr(III) sequestration in a wide pH range. Benefiting from its abundant interaction sites, Cr(VI) was effectively adsorbed on the surface and then immediately reduced to Cr(III) with much lower toxicity. Most importantly, the resulting Cr(III) was in-situ sequestrated by the complexation of chitosan matrix. As a result, PPy@PMCS exhibited a maximum Cr(VI) adsorption capacity of 330.42 mg/g at pH 2.0 and an adsorption capacity of 167.82 mg/g even at near neutral pH (6.0), which is superior to most reported adsorbents. Furthermore, the exhausted PPy@PMCS can be rapidly separated from solutions under an external magnetic field and facilely regenerated. The proposed novel biopolymer-based material shows great application potentials in wastewater treatment.

Porous gelatin microspheres implanted with adipose mesenchymal stromal cells promote angiogenesis via protein kinase B/endothelial nitric oxide synthase signaling pathway in bladder reconstruction

Background aimsCell failure and angiogenesis are the key to bladder wall regeneration. Three-dimensional (3D) culture using porous gelatin microspheres (GMs) as a vehicle promotes stem cell proliferation and improves the paracrine capacity of cells. This study aimed to evaluate the therapeutic potential of GMs constructed from adipose-derived mesenchymal stromal cells (ADSCs) (ADSC-GMs) combined with bladder acellular matrix (BAM) in tissue-engineered bladders. MethodsIsolation of ADSCs, flow cytometry, scanning electron microscopy and cell counting kit-8, β-galactosidase and enzyme-linked immunosorbent assays were performed in vitro to compare two-dimensional (2D) and 3D cultures. In the in vivo study, male Sprague–Dawley rats were randomly divided into three groups: the BAM replacement alone (BAM) group, ADSCs grown on BAM in replacement (ADSC) group and ADSC-GMs combined with BAM followed by replacement (ADSC-GM) group. Bladder function assessed by urodynamics after 12 weeks of bladder replacement, and the rats were sacrificed at 4 and 12 weeks for further experiments. ResultsThe in vitro results showed that GM culture promoted ADSC proliferation, inhibited apoptosis and delayed senescence compared with those in the 2D culture. In addition, ADSC-GMs increased the secretion of the angiogenic factors vascular endothelial growth factor, platelet-derived growth factor-BB, and basal fibroblast growth factor. In vivo experiments revealed that ADSC-GMs adhered to the BAM for longer than ADSCs. Moreover, ADSC-GMs significantly promoted the regeneration of bladder vessels and smooth muscle, thereby facilitating the recovery of bladder function. The expression of phosphorylated protein kinase B (AKT) and phosphorylated endothelial nitric oxide synthase (eNOS) was significantly greater in the ADSC-GMs group compared with the BAM and ADSCs groups. ConclusionsADSC-GMs increased retention of ADSCs on the BAM, thereby promoting the regeneration and functional recovery of the bladder tissue. ADSC-GMs promoted angiogenesis by activating the AKT/eNOS pathway.

Glutamic based self-assembly urchin microsphere structure metal organic framework for gas sorption and aluminium ion sensing applications

Bio-molecules based self-assembled nano range metal-organic frameworks (MOFs) potential materials used in recent compact applications. For its structural tunability, large void area, pore volumes and eco-friendly nature. In this work, we report the same composition but different synthesized method glutamic acid cobalt node-based metal-organic compounds GACo1 and GACo2. In this material, GACo2 has the property of a nanocrystalline nature, this fundamental combination forms self-assembly uniform well-developed porous 3D urchin-like microsphere architectures with the dimension of 1.5 µm. The sorption analysis declares N2 adsorbed in the amount of 1544 ccg−1 and surface area is 2695 m2 g−1 without supercritical CO2 treatment. Interestingly, GACo2 MOF acts as a fluorescence probe for Al3+ metal ions in the aqueous phase with high selectivity and sensitivity. The KSV value and detection limit of material were 2.13 × 103 M−1 and 0.0547 × 10−7 M respectively, Also, the limit of detection is significantly lower than the WHO recommendation of Al3+ ion for drinking water ((7.41310−3 M)). Interestingly, the turn-on-sensing ability of GACo2 MOF for Al3+ ions in an aqueous medium was achieved even in the presence of a change in the pH of the solution.

Bamboo fiber-derived porous carbon microspheres decorated with MnO2 for enhanced supercapacitor performance

Manganese dioxide holds great potential as a pseudocapacitive material for supercapacitors. However, its limited electrical conductivity hampers the realization of its theoretically predicted capacitance. In this study, we successfully synthesized MnO2 in-situ on porous carbon microspheres derived from bamboo pulp fibers using a hydrothermal method. The morphology and phase of MnO2 were controlled by adjusting reduction reaction of KMnO4. Porous carbon spheres coated with sheet-like δ-MnO2 were obtained at a low Mn/C ratio, resulting in an impressive specific surface area of 401.4 m2 g−1. The composite exhibited remarkable specific capacitance of 364.4 F g−1 at a current density of 0.5 A g−1 and exhibited excellent capacitance retention of 99.7 % after undergoing 10,000 cycles. Incorporation of MnO2 improved the capacitance performance of porous carbon spheres by 81 %. This study presents promising prospects for the sustainable and environmentally friendly production of bamboo-derived carbon composite materials for supercapacitors.

Porous Fe1-xS/C microspheres constructed by L-aspartic acid as high-performance anode material for lithium-ion batteries

Porous microspherical structure for metal oxides or sulfides as anode material exhibits dramatic advantages in improving electrochemical properties of lithium-ion batteries (LIBs). Herein, porous Fe1-xS microspheres with uniform size were synthesized through a hydrothermal reaction where L-aspartic acid molecules guide crystal growth and form secondary particles. The microsphere with perforated channels provides facile channels for the migration of Li+ and accommodates mechanical stress to suppress volume expansion. The residual carbon decomposed from the L-aspartic acid molecules in the final composite also facilitates the electron transfer and prevents polysulfides from dissolving into electrolyte. Thus, the Fe1-xS/C maintains superior structural stability in a long cycling with excellent reversible capacity at high rates. Specifically, the Fe1-xS/C electrode deliverers a capacity of 534 mAh g−1 at 20 A g−1 and lefts 810 mAh g−1 after 3000 cycles at 5 A g−1.

Preparation, characterization, and adsorption performance of porous polyamine lignin microsphere

In this study, a porous polyamine lignin microsphere (PPALM) was prepared through the inverse suspension polymerization combined with freeze-drying, during which sodium lignosulfonate and polyetheramine (PEA) were crosslinked with epichlorohydrin (ECH) as the cross-linker. By adjusting the amount of ECH and PEA, the optimized PPALM exhibited suitable crosslinking degree, ensuring a balance of framework flexibility and rigidity, thereby facilitating the formation of abundant and fine pores. PPALM demonstrated good mechanical properties comparable to commercial sulfonated polystyrene cationic resin, with a porosity of 61.12 % and an average pore size of 283.51 nm. The saturation adsorption capacity of PPALM for Pb2+ was measured to be 156.82 mg/g, and it remained above 120 mg/g after five cycles of regeneration. Particularly, the concentration of 50 mg/L Pb2+ solution could be reduced to 0.98 mg/L after flowing through the PPALM packed bed, indicating the great potential of PPALM for application in wastewater treatment.

Synthesis of Iron Sulfide Nanocrystals Encapsulated in Highly Porous Carbon-Coated CNT Microsphere as Anode Materials for Sodium-Ion Batteries.

Highly porous carbon materials with a rationally designed pore structure can be utilized as reservoirs for metal or nonmetal components. The use of small-sized metal or metal compound nanoparticles, completely encapsulated by carbon materials, has attracted significant attention as an effective approach to enhancing sodium ion storage properties. These materials have the ability to mitigate structural collapse caused by volume expansion during the charging process, enable short ion transport length, and prevent polysulfide elution. In this study, a concept of highly porous carbon-coated carbon nanotube (CNT) porous microspheres, which serve as excellent reservoir materials is suggested and a porous microsphere is developed by encapsulating iron sulfide nanocrystals within the highly porous carbon-coated CNTs using a sulfidation process. Furthermore, various sulfidation processes to determine the optimal method for achieving complete encapsulation are investigated by comparing the morphologies of diverse iron sulfide-carbon composites. The fully encapsulated structure, combined with the porous carbon, provides ample space to accommodate the significant volume changes during cycling. As a result, the porous iron sulfide-carbon-CNT composite microspheres exhibited outstanding cycling stability (293mA h g-1 over 600 cycles at 1 A g-1 ) and remarkable rate capability (100mA h g-1 at 5 A g-1 ).

Polysaccharide-Based Composite Hydrogel with Hierarchical Microstructure for Enhanced Vascularization and Skull Regeneration.

Critical-size skull defects caused by trauma, infection, and tumor resection raise great demands for efficient bone substitutes. Herein, a hybrid cross-linked hierarchical microporous hydrogel scaffold (PHCLS) was successfully assembled by a multistep procedure, which involved (i) the preparation of poly(lactic-co-glycolic)/nanohydroxyapatite (PLGA-HAP) porous microspheres, (ii) embedding the spheres in a solution of dopamine-modified hyaluronic acid and collagen I (Col I) and cross-linking via dopamine polyphenols binding to (i) Col I amino groups (via Michael addition) and (ii) PLGA-HAP (via calcium ion chelation). The introduction of PLGA-HAP not only improved the diversity of pore size and pore communication inside the matrix but also greatly enhanced the compressive strength (5.24-fold, 77.5 kPa) and degradation properties to construct a more stable mechanical structure. In particular, the PHCLS (200 mg, nHAP) promoted the proliferation, infiltration, and angiogenic differentiation of bone marrow mesenchymal stem cells in vitro, as well as significant ectopic angiogenesis and mineralization with a storage modulus enhancement of 2.5-fold after 30 days. Meanwhile, the appropriate matrix microenvironment initiated angiogenesis and early osteogenesis by accelerating endogenous stem cell recruitment in situ. Together, the PHCLS allowed substantial skull reconstruction in the rabbit cranial defect model, achieving 85.2% breaking load strength and 84.5% bone volume fractions in comparison to the natural cranium, 12 weeks after implantation. Overall, this study reveals that the hierarchical microporous hydrogel scaffold provides a promising strategy for skull defect treatment.

Imidazole-octyl mixed-mode stationary phase based on macroporous silica for the purification of ovomucoid and ovotransferrin.

A process-simplified hard template approach was established to synthesize the monodisperse macroporous silica microspheres with homogeneous structures by twice alkali-thermal treatment and calcination routes. Porous vinyl-functionalized polysesquioxane microspheres (V-PMSQ) were synthesized through a hydrolyzation-polycondensation method and used as templates. The template particles with large aperture and high pore volume were obtained by adjusting the pH value and reaction time of the twice alkali-thermal reaction. After calcination, monodisperse silica microspheres with an average pore size of 30nm, homogeneous pore structures, and narrow particle size distribution were fabricated, which can be directly used as chromatographic matrices without classification. After that, a new reversed-phase/strong anion-exchange (RP/SAX) mixed-mode stationary phase Sil-S-VOIM was prepared by bonding the 1-vinyl-3-octyl-imidazole ligands to the above silica microspheres through a "thiol-ene" click reaction. The performance of the Sil-S-VOIM column was evaluated by one acidic protein (transferrin) and two basic proteins (lysozyme, α-chymotrypsin) and compared to a single imidazole-modified Sil-S-VIM column and an octyl-modified Sil-C8 column, respectively. Due to the synergistic effect of electrostatic repulsion and hydrophobic interactions, baseline separations of the above proteins were observed only on the Sil-S-VOIM column, with resolutions of 2.55 and 2.01 between lysozyme and transferrin, and between transferrin and α-chymotrypsin, respectively, indicating good selectivity and separation ability compared with single-mode stationary phases. It was applied to the isolation of egg white samples with peaks identified by SDS-PAGE and MALDI-TOF-MS. The results showed that the selective retention and isolation of ovomucoid and ovotransferrin were successfully achieved, with yields of 78.8% and 67.2%, respectively. The protocol described in this work is simpler, faster, and has higher protein recovery. Overall, this new mixed-mode stationary phase provided a promising potential for the separation and determination of intact proteins.

Propylene Metathesis over Molybdenum Silicate Microspheres with Dispersed Active Sites.

In this work, we demonstrate that amorphous and porous molybdenum silicate microspheres are highly active catalysts for heterogeneous propylene metathesis. Homogeneous molybdenum silicate microspheres and aluminum-doped molybdenum silicate microspheres were synthesized via a nonaqueous condensation of a hybrid molybdenum biphenyldicarboxylate-based precursor solution with (3-aminopropyl)triethoxysilane. The as-prepared hybrid metallosilicate products were calcined at 500 °C to obtain amorphous and porous molybdenum silicate and aluminum-doped molybdenum silicate microspheres with highly dispersed molybdate species inserted into the silicate matrix. These catalysts contain mainly highly dispersed MoOx species, which possess high catalytic activity in heterogeneous propylene metathesis to ethylene and butene. Compared to conventional silica-supported MoOx catalysts prepared via incipient wetness impregnation (MoIWI), the microspheres with low Mo content (1.5-3.6 wt %) exhibited nearly 2 orders of magnitude higher steady-state propylene metathesis rates at 200 °C, approaching site time yields of 0.11 s-1.