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Introducing continuous mesochannels into covalent organic frameworks (COFs) to increase the accessibility of their inner active sites has remained a major challenge. Here, we report the synthesis of COFs with an ordered bicontinuous mesostructure, via a block copolymer self‐assembly‐guided nanocasting strategy. Three different mesostructured COFs are synthesized, including two covalent triazine frameworks and one vinylene‐linked COF. The new materials are endowed with a hierarchical meso/microporous architecture, in which the mesochannels exhibit an ordered shifted double diamond (SDD) topology. The hierarchically porous structure can enable efficient hole‐electron separation and smooth mass transport to the deep internal of the COFs and consequently high accessibility of their active catalytic sites. Benefiting from this hierarchical structure, these COFs exhibit excellent performance in visible‐light‐driven catalytic NO removal with a high conversion percentage of up to 51.4 %, placing them one of the top reported NO‐elimination photocatalysts. This study represents the first case of introducing a bicontinuous structure into COFs, which opens a new avenue for the synthesis of hierarchically porous COFs and for increasing the utilization degree of their internal active sites. [ABSTRACT FROM AUTHOR]

Rechargeable sodium/chlorine (Na/Cl2) batteries are emerging candidates for sustainable energy storage owing to their superior energy densities and the high abundance of Na and Cl elements. However, their practical applications have been plagued by the poor rate performance (e.g., a maximum discharge current density of 150 mA g−1), as the widely used carbon nanosphere cathodes show both sluggish electron‐ion transport and reaction kinetics. Here, by mimicking the sufficient mass and energy transport in a sponge, we report a bicontinuous‐structured carbon cubosome with heteroatomic doping, which allows efficient Na+ and electron transport and promotes Cl2 adsorption and conversion, thus unlocking ultrahigh‐rate Na/Cl2 batteries, e.g., a maximum discharge current density of 16,000 mA g−1 that is more than two orders of magnitude higher than previous reports. The optimized solid–liquid–gas (carbon–electrolyte–Cl2) triple interfaces further contribute to a maximum reversible capacity and cycle life of 2,000 mAh g−1 and 250 cycles, respectively. This study establishes a universal approach for improving the sluggish kinetics of conversion‐type battery reactions, and provides a new paradigm to resolve the long‐standing dilemma between high energy and power densities in energy storage devices. [ABSTRACT FROM AUTHOR]

This paper reports the conversion of a waste to a conducting material, exploiting the ability to adsorb pollutant organic dyes. Leather waste was carbonized at 800 °C in an inert nitrogen atmosphere. The resulting biochar was used for in-situ deposition of polypyrrole nanotubes produced by the oxidative polymerization of pyrrole in the presence of methyl orange. The composites of carbonized leather with deposited polypyrrole nanotubes of various composition were compared with similar composites based on globular polypyrrole. Their molecular structure was characterized by infrared and Raman spectra. Both conducting components formed a bicontinuous structure. The resistivity was newly determined by a four-point van der Pauw method and monitored as a function of pressure applied up to 10 MPa. The typical conductivity of composites was of the order of 0.1 to 1 S cm−1 and it was always higher for polypyrrole nanotubes than for globular polypyrrole. The method also allows for the assessment of mechanical features, such as powder fluffiness. The conductivity decreased by 1–2 orders of magnitude after treatment with ammonia but still maintained a level acceptable for applications operating under non-acidic conditions. The composites were tested for dye adsorption, specifically cationic methylene blue and anionic methyl orange, using UV-vis spectroscopy. The composites were designed for future use as functional adsorbents controlled by the electrical potential or organic electrode materials. [ABSTRACT FROM AUTHOR]

We demonstrate a general strategy for the synthesis of ordered bicontinuous‐structured metal organic frameworks (MOFs) by using polymer cubosomes (PCs) with a double primitive structure (Im3‾ ${\bar{3}}$ m symmetry) as the template. The filling of MOF precursors in the open channel of PCs, followed by their coordination and removal of the template, generates MOF cubosomes with a single primitive topology (Pm3‾ ${\bar{3}}$ m) and average mesopore diameters of 60–65 nm. Mechanism study reveals that the formation of ZIF‐8 cubosomes undergoes a new MOF growth process, which involves the formation of individual MOF seeds in the template, their growth and eventual fusion into the cubosomes. Their growth kinetics follows the Avrami equation with an Avrami exponent of n=3 and a growth rate of k=1.33×10−4, indicating their fast 3D heterogeneous growth mode. Serving as a bioreactor, the ZIF‐8 cubosomes show high loading of trypsin enzyme, leading to a high catalytic activity in the proteolysis of bovine serum albumin. [ABSTRACT FROM AUTHOR]

Bicontinuous microparticles have advanced transport, mechanical, and electrochemical properties and show promising applications in energy storage, catalysis, and other fields. However, it remains a great challenge to fabricate bicontinuous microparticles of block copolymers (BCPs) by controlling the microphase separation due to the extremely narrow region of a bicontinuous structure in the phase diagram. Here, we demonstrate a strategy to balance the phase separation of BCPs and fluorinated additives at different length scales in emulsion droplets, providing a large window to access bicontinuous microparticles. The key point is to simultaneously introduce contradictory attractive-repulsive interactions between poly(4-vinylpyridine)-containing BCPs and carboxylated perfluorinated additives. Hydrogen bonding between poly(4-vinylpyridine) and carboxyl groups, as an attractive interaction, directs the microphase separation between BCPs and additives. Meanwhile, the repulsive interaction due to the high immiscibility between perfluoroalkyl residues and BCPs induces macrophase separation. The compromise of attractive-repulsive interactions triggers the formation of bicontinuous microparticles in a large phase space. In addition, the vulnerable nature of hydrogen bonding provides a flexible route for reversibly shaping BCP assemblies. This work establishes a platform for fabricating structured BCP microparticles of which the structures are hardly accessible through traditional solution self-assembly.

The surface curvature of catalysts has a decisive impact on their catalytic performance. However, the influence of a negative-Gaussian-curvature surface on the catalytic performance of porous catalysts has remained unexplored due to the lack of suitable samples. Bicontinuous-structured porous structures can serve as ideal models, but they are known as "Plumber's nightmare" due to their highly difficult preparation. Here, using metal-organic frameworks as the precursor and polymer cubosomes as the template, a bicontinuous mesoporous Fe single-atom catalyst (named bmFeSAC) with a Schwarz P surface is synthesized. The bmFeSAC catalyst has a large specific surface area of 916 m 2  g -1 and uniformly distributed Fe-N 4 active sites with a 1.80 wt.% Fe content. The continuous channels enabled high utilization efficiency of the Fe-N 4 catalytic sites, while the negative-Gaussian-curvature surface enabled low reaction energy barrier. As an electrocatalyst of the oxygen reduction reaction, bmFeSAC delivered a high half-wave potential of 0.931 V versus. RHE in alkaline electrolyte, reaching the leading level among those of the reported state-of-the-art electrocatalysts. Furthermore, the bmFeSAC-based Zn-air batteries exhibited excellent performance, demonstrating the potential application of bmFeSAC. This study revealed that a bicontinuous-structured porous structure can improve catalytic activity by increasing the utilization ratio of catalytic sites and, more importantly, by regulating the electronic structure of catalyst surfaces through the negative-Gaussian-curvature., (© 2024 Wiley‐VCH GmbH.)

Liquid-metal dealloying generates porous metals or interpenetrating-phase composites. Particularly attractive is the use of the alloy's innate melt for activating dealloying throughout the bulk, even in extended sample geometries, during reverse peritectic melting. We explore if interpenetrating-phase microstructures may be observed more generally during partial melting of solid solutions with an extended temperature interval of solid-melt coexistence. Incomplete wetting of grain boundaries by the melt is then a prerequisite for a bicontinuous structure. For a Cu-In alloy, we show that special grain boundaries remain non-wetted and provide a load-bearing backbone in the partially molten alloy, and that the bicontinuous structure is preserved during quenching to room temperature. Samples with a contiguous porosity can be obtained by leaching the solidified melt. As extended melting intervals are ubiquitous in binary alloys, our observations provide for the innate-melt-enabled preparation of monolithic interpenetrating-phase composites or porous metals in an extended set of alloy systems. [ABSTRACT FROM AUTHOR]

1,6-hexanediol diacrylate (HDDA) or divinyl adipate (DVA) and pentaerythritol tetrakis(3-mercaptopropionate) (TT) were polymerised via a thiol-ene radical initiated photopolymerisation using emulsions with a high volume fraction of internal droplet phase and monomers in the continuous phase as precursors. The porous structure derived from the high internal phase emulsions (HIPEs) followed the precursor emulsion setup resulting in an open porous cellularly structured polymer. Changing the emulsion composition and polymerisation conditions influenced the resulting morphological structure significantly. The investigated factors influencing the polymer monolith morphology were the emulsion phase ratio and surfactant concentration, leading to either interconnected cellular type morphology, bicontinuous porous morphology or a hollow sphere inverted structure of the polymerised monoliths. The samples with interconnected cellular morphology had pore diameters between 4 µm and 10 µm with approx. 1 µm sized interconnecting channels while samples with bicontinuous morphology featured approx. 5 µm wide pores between the polymer domains. The appropriate choice of emulsion composition enabled the preparation of highly porous poly(thiol-enes) with either polyHIPE or bicontinuous morphology. The porosities of the prepared samples followed the emulsion droplet phase share and could reach up to 88%. [ABSTRACT FROM AUTHOR]

Transparent glass-ceramic fibers containing fluoride nanocrystals are attracting attention as upconversion devices. In this paper, a material design is proposed that eliminates the need for heat treatment processes. The impact of short- to medium-range structures on the crystallization of glasses was investigated to enable nanocrystallization in the quenching process via ultrafast nucleation. In this study, the short- to medium-range structures of (33.3 - x/3)-BaF2-xZnO-(66.7 - 2x/3)-B2O3 glasses were investigated by 11B- and 19F-magic-angle spinning nuclear magnetic resonance spectroscopy, molecular dynamics simulations, and the high-energy synchrotron X-ray diffraction. After heat treatment, glasses with x > 40 formed BaF2 nanocrystals with a diameter of ~5 nm and a small particle size distribution (<1 nm). Based on the high-energy synchrotron X-ray diffraction, the critical size of the nuclei was estimated to be 4 nm, which was similar to the size of the precipitated crystals. Obvious selectivity in the binding was observed: F- preferred Ba2+ and O2- preferred B3+, whereas Zn2+ was bound to both anions. The binding selectivity caused a bicontinuous structure of oxide and fluoride domains, and the fluoride-related structure factors and bond distance were very similar to the peak positions of the precipitated crystals. Er3+-doped glasses with x > 40 showed upconversion luminescence with a spectrum similar to that of BaF2. These results suggested the pre-existence of a crystal-like structure with a composition, density, and ordering similar to those of the precipitated crystals. Moreover, glass with the modified composition was successfully crystallized during press-quenching of the melt and the fiber drawing process. These results could facilitate the production of photonic components such as nanocrystallized glass fibers and microspheres for upconversion lasers as well as a wide variety of glass-ceramic products. [ABSTRACT FROM AUTHOR]

Nanoporous metals having large surface area and unique bicontinuous structure have attracted much attention due to the excellent functional properties. Conventionally, nanoporous metals were prepared by dealloying in aqueous solution, which is a selective corrosion of less-noble component from the multicomponent alloy. However, the corrosion-based dealloying can only be applicable to synthesize noble nanoporous metals. We have recently developed an innovative dealloying method using liquid metal, termed as liquid metal dealloying, in which nanoporous metal is evolved in a liquid metal. We have successfully prepared various nanoporous less-noble metals in Ti, Nb, V, Cr, Fe, Si, and C which could not be synthesized in the aqueous solution. The developed nanoporous metals exhibited excellent performance as energy related materials. For example, nanoporous Si improved cyclic performance of the lithium-ion battery anode because the many open channels act as ideal volume expansion buffers. Nanoporous Nb significantly increased mass-specific capacitance in electrolytic capacitor because bicontinuous nanostructure was ideal for uniform formation of dielectric layer while keeping large surface area and conduction path. The liquid metal dealloying is a versatile technique that can be used to synthesize nanoporous less-noble metals, nano hetero composite materials and to modify the surface and composition of structural materials. [ABSTRACT FROM AUTHOR]

Titania has received considerable attention as a promising anode material of Li-ion battery (LIB). Controlling the structure and morphology of titania nanostructures is crucial to govern their performance. Herein, we report a mesoporous titania scaffold with a bicontinuous shifted double diamond (SDD) structure for anode material of LIB. The titania scaffold was synthesized by the cooperative self-assembly of a block copolymer poly(ethylene oxide)-block-polystyrene template and titanium diisopropoxide bis(acetylacetonate) as the inorganic precursor in a mixture solvent of tetrahydrofuran and HCl/water. The structure shows tetragonal symmetry (space group I41/amd) comprising two sets of diamond networks adjoining each other with the unit cell parameter of a = 90 nm and c = 127 nm, which affords the porous titania a specific surface area (SSA) of 42 m2·g−1 with a mean pore diameter of 38 nm. Serving as an anode material of LIB, the bicontinuous titania scaffold exhibits a high specific capacity of 254 mAh·g−1 at the current density of 1 A·g−1 and an alluring self-improving feature upon charge/discharge over 1,000 cycles. This study overcomes the difficulty in building up ordered bicontinuous functional materials and demonstrates their potential in energy storage application. [ABSTRACT FROM AUTHOR]

Bicontinuous nanoporous metallic glasses (MG) synergize the outstanding properties of MGs and open-cell nanoporous materials. The low-density and high-specific-surface-area of bicontinuous nanoporous structures have the potential to enhance the applicability of MGs in catalysis, sensors, and lightweight structural designs. Here, we report molecular dynamics simulations of tensile loading deformation and failure of bicontinuous nanoporous Cu 64 Zr 36 MG with 55% porosity and 4.4 nm ligament size. Results indicate an anomalous mechanical behavior featuring delocalized plastic deformation preceding ductile failure. The deformation follows two mechanisms: i) Necking of ligaments aligned with the loading direction and ii) progressive alignment of randomly oriented ligaments. Failure occurs at 0.16 strain, following massive rupture of ligaments. This work indicates that a bicontinuous nanoporous design is able to effectively delocalize strain localization in a MG due to a combination of size effect on the ductility of MGs resulting in nano ligaments necking and progressive asynchronous alignment of ligaments. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The rapid development of electronic communication technology has led to an undeniable issue of electromagnetic pollution, prompting widespread attention from researchers to the study of electromagnetic shielding materials. Herein, a simple and feasible method of melt blending was applied to prepare iPP/TPU/MWCNT nanocomposites with excellent electromagnetic shielding performance. The addition of maleic anhydride-grafted polypropylene (PP-g-MAH) effectively improved the interface compatibility of iPP and TPU. A double continuous structure within the matrix was achieved by controlling the iPP/TPU ratio at 4:6, while the incorporation of multi-walled carbon nanotubes endowed the composites with improved electromagnetic shielding properties. Furthermore, by regulating the addition sequence of raw materials during the melt-blending process, a selective distribution of carbon nanotubes in the TPU matrix was achieved, thereby constructing interconnected conductive networks within the composites, significantly enhancing the electromagnetic shielding performance of iPP/TPU/MWCNTs, which achieved a maximum EMI shielding efficiency of 37.8 dB at an iPP/TPU ratio of 4:6 and an MWCNT concentration of 10 wt.%.

The emerging sodium-ion batteries (SIBs) are one of the most promising candidates expected to complement lithium-ion batteries and diversify the battery market. However, the exploitation of cathode materials with high-rate performance and long-cycle stability for SIBs has remained one of the major challenges. To this end, an efficient approach to enhance rate and cycling performance by introducing an ordered bicontinuous porous structure into cathode materials of SIBs is demonstrated. Prussian blue analogues (PBAs) are selected because they are recognized as a type of most promising SIB cathode materials. Thanks to the presence of 3D continuous channels enabling fast Na + ions diffusion as well as the intrinsic mechanical stability of bicontinuous architecture, the resultant PBAs exhibit excellent rate capability (80 mAh g -1 at 2.5 A g -1 ) and ultralong cycling life (>3000 circulations at 0.5 A g -1 ), reaching the top performance of the reported PBA-based cathode materials. This study opens a new avenue for boosting sluggish ion diffusion kinetics in electrodes of rechargeable batteries and also provides a new paradigm for solving the dilemma that electrodes' failure due to high-stress concentration upon ion storage., (© 2024 Wiley‐VCH GmbH.)

A series of hierarchically porous SrTiO3 films with different pore structure characteristics from bicontinuous macroporous–mesoporous structure to ordered and fragmented structures have been synthesized using sol–gel method, by controlling the competition between polyethylene glycol (PEG)-induced phase separation and sol–gel transition. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, X-ray diffractometry (XRD) and photoluminescence (PL) spectroscopy were used to characterize the as-prepared samples. The bicontinuous structured SrTiO3 porous film constructed by irregular grains possessed three-dimensional (3D) interconnected network with both macropores (80–400 nm) and mesopores (1–10 nm), which provides abundant active sites (the specific surface area up to 121.9 m2/g) and ensures fast mass transfer simultaneously. In addition, PL spectra illustrated that the film consisting of 3D bicontinuous macroporous– and mesopores has a relatively low photocarrier recombination rate. As a result, the SrTiO3 film with 3D bicontinuous porous structure exhibits more outstanding photocatalytic behavior with high degradation capability for Rhodamine B (RhB) (99.8% after 90 min irradiation by 500 W mercury lamp) than the others. Moreover, nearly 80% of the degradation efficiency can be achieved after five cycles. Highlights: 3D bicontinuous structured SrTiO3 porous films with improved photocatalytic activity. Sol–gel process with controlled phase separation. Synergistic and temporal effects of PEG and diethanolamine (DEA). Dynamic change from bicontinuous macroporous–mesoporous structure to fragmented structure. [ABSTRACT FROM AUTHOR]

The use of green solvents satisfies safer chemical engineering practices and environmental security. Herein, myristic acid (MA)—a green diluent—was selected to prepare poly- (4-methyl-1-pentene) (PMP) membranes with bicontinuous porous structure via a thermally induced phase separation (TIPS) process to maintain a high gas permeability. Firstly, based on the Hansen solubility parameter ‘distance’, Ra, the effect of four natural fatty acids on the PMP membrane structure was compared and studied to determine the optimal green diluent, MA. The thermodynamic phase diagram of the PMP-MA system was calculated and presented to show that a liquid-liquid phase separation region could be found during the TIPS process and the monotectic point was around 34.89 wt%. Then, the effect of the PMP concentration on the morphologies and crystallization behavior was systematically investigated to determine a proper PMP concentration for the membrane preparation. Finally, PMP hollow fiber (HF) membranes were fabricated with a PMP concentration of 30 wt% for the membrane performance characterization. The resultant PMP HF membranes possessed good performances that the porosity was 70%, the tensile strength was 96 cN, and the nitrogen flux was 8.20 ± 0.10 mL·(bar·cm2·min)−1. We believe that this work can be a beneficial reference for people interested in the preparation of PMP membranes for medical applications.

A new type of porous carbon/MnO 2 composites, having bicontinuous structures, i.e., continuous channels and carbon skeletons, was prepared using a phase separation method, followed by a carbonization procedure and a subsequent redox reaction. In this work, such composite electrodes show a high specific capacitance of ca. 260 F g −1 at 0.5 A g −1 in 1 M Na 2 SO 4 aqueous solution, a superior cycling stability (~80% retention after 2000 cycles) and a distinctive high-rate performance. Especially, unique bicontinuous structures endow such composites with a great specific capacitance of the constituent MnO 2 (~1100 F g −1 ), very close to the theoretical value. These excellent electrochemical behaviors may render this material a promising candidate as high-performance electrodes in supercapacitors. Therefore, our findings suggest that the strategy for constructing bicontinuous hybrid electrodes represents an exciting direction for designing next-generation supercapacitors. [ABSTRACT FROM AUTHOR]

Titanium-magnesium (Ti-Mg) composites with bicontinuous structure have been successfully fabricated by powder metallurgy and ultrasonic infiltration for biomaterial potential. In the composites, Ti phase is distributed continuously by sintering necks, while Mg phase is also continuous, distributing at the interconnected pores surrounding the Ti phase. The results showed that the fabricated Ti-Mg composites exhibited low modulus and high strength, which are very suitable for load bearing biomedical materials. The composites with 100 µm and 230 µm particle sizes exhibited Young's modulus of 37.6 GPa and 23.4 GPa, 500.7 MPa and 340 MPa of compressive strength and 631.5 MPa and 375.2 MPa of bending strength, respectively. Moreover, both of the modulus and strength of the composites increase with decreasing of Ti particle sizes. In vitro study has been done for the preliminary evaluation of the Ti-Mg composites. [ABSTRACT FROM AUTHOR]

The ECTFE membrane with bicontinuous structure was prepared by a binary diluent via thermally induced phase separation method. The effect of binary diluent composition on membrane structure was investigated systematically. The Flory–Huggins interaction parameters between ECTFE and diluents were investigated to analyze the mechanism of phase separation. Dibutyl sebacate (DBS) was selected as the primary diluent due to the high boiling point and strong interaction with ECTFE, while triphenyl phosphite (TPP) was selected as the secondary diluent because of the good compatibility with DBS. As the weight ratio of DBS to TPP was 3/2, a uniform bicontinuous structure was obtained. A typical upper critical solution temperature behavior was displayed and the monotectic concentration was as high as approximately 50 wt.%. Finally, an ECTFE hollow fiber membrane with a bicontinuous structure was prepared by the binary diluent and revealed high mechanical strength (tensile strength of 2.40 MPa) and filtration performance (water flux of 313 L m−2 h−1at 0.1 MPa). [ABSTRACT FROM PUBLISHER]

Lactic acid is a promising biogenic platform chemical which can be produced by fermentation of cellulose and hemicellulose. However, separating lactic acid from the fermentation broth is extremely costly and technically complex. We therefore investigated whether liquid/liquid extraction of lactic acid with tri- n-octylamine is a cost-effective alternative to the existing downstream processing method. In order to find an answer to this question, the structure of the middle phase of the occurring three-phase region, which is enriched with up to 20 wt. % lactic acid, was explored. The results of our IR, small-angle X-ray scattering and NMR measurements show that this phase is ionic and has a bicontinuous structure. Due to the analogy with bicontinuous microemulsions, it should be possible to further enrich the lactic acid, which could lead to a rethink regarding the design of extraction processes. [ABSTRACT FROM AUTHOR]

Bicontinuous Tin oxide (SnO 2 ) thin films were fabricated by atomic layer deposition (ALD), annealing, and acid washing with nanoporous gold (NPG) structure serving as templates. The resultant SnO 2 films show high sensitivity on NO 2 gas. The detection limit is as low as 170 ppb in dry N 2 flow with a rapid response/recovery time of 40/130 s at the optimized working temperature of 300 °C. The performances dependence of the gas sensor on the working temperatures and the exposure environments reveal that the gas responses strongly rely on the dynamic balance of O 2 , O 2 − , O − , N O 2 − , and N O 3 − . Our study not only shows this bicontinuous SnO 2 films is promising for sensitive gas sensor but also provides insightful understanding on the NO 2 gas sensing mechanism. [ABSTRACT FROM AUTHOR]

TiO 2 has been considered as a promising intercalation lithium-ion-battery (LIB) anode material owing to its robust cyclability. However, it suffers from low capacity. Herein, we construct a sub 10 nm scale interfused TiO 2 /SiO x hybrid with a bicontinuous structure, in which bridged TiO 2 nanoparticles (over 80 wt %) are densely packed within a wormlike SiO x network, through the simple oxidation of MAX Ti 3 SiC 2 ceramic. State-of-the-art in situ microscopy characterization unravels a "mutual-stabilizing" effect from the interfused TiO 2 /SiO x hybrid upon lithiation. That is to say, the two interpenetrated active components restrain the volume expansion of each other with the stress being relieved through abundant interfaces. Meanwhile, the stress generated from one phase functioned as the compressive force on the other phase and vice versa, offsetting the overall volume effect and synergistically reinforcing the structure integrity. Benefiting from the "mutual-stabilizing" effect, the TiO 2 /SiO x composite manifests a high and stable specific capacity (∼671 mAh g -1 after 580 cycles at 0.1 A g -1 ) with a low volume expansion of ∼14% even in an extended potential window of 0.01-3.0 V (vs Li + /Li). The concept of mutual-stabilizing effect, in principle, applies to a wide class of interfused bicontinuous hybrids, providing insight into the design of LIB anode materials with high capacity and longevity.

Porous materials with their ordered bicontinuous structures have attracted great interest owing to ordered periodic structures as well as 3D interconnected network and pore channels. Bicontinuous structures may favor efficient mass diffusion to the interior of materials, thus increasing the utilization ratio of active sites. In addition, ordered bicontinuous structures confer materials with exceptional optical and magnetic properties, including tunable photonic bandgap, negative refraction, and multiple equivalent magnetization configurations. The attractive structural advantages and physical properties have inspired people to develop strategies for preparing bicontinuous-structured porous materials. Among a few synthetic approaches, the self-assembly of block copolymers represents a versatile strategy to prepare various bicontinuous-structured functional materials with pore sizes and lattice parameters ranging from 1 to 500 nm. This article overviews progress in this appealing area, with an emphasis on the synthetic strategies, the structural control (including topologies, pore sizes, and unit cell parameters), and their potential applications in energy storage and conversion, metamaterials, photonic crystals, cargo delivery and release, nanoreactors, and biomolecule selection., (© 2022 Wiley-VCH GmbH.)

ABSTRACT With diphenyl ketone as diluent, cellulose acetate (CA) ultrafiltration (UF) membrane with a bicontinuous structure was prepared via thermally induced phase separation (TIPS) method. The liquid-liquid phase separation region of CA/diphenyl ketone system was measured and the maximum corresponding polymer concentration was approximately 53 wt %. The effects of polymer concentration, coarsening time and coarsening temperature on the morphologies, and mechanical properties of CA membranes were investigated systematically. As the polymer concentration increased from 15 to 30 wt %, the bicontinuous structure could be obtained and the tensile strength of CA membranes increased from 3.92 to 30.17 MPa. With the increase of coarsening time, the thickness of dense skin layer and the asymmetry of cross-section reduced. However, excess coarsening rendered the membrane morphology evolved from a bicontinuous structure to a cellular structure. When the coarsening time was 5 min, the bicontinuous structure in cross-section showed good interconnectivity and the dense skin layer exhibited a thin thickness of 2 μm. The fabricated CA hollow fiber UF membrane exhibited a high tensile strength of 31.00 MPa and rejection of 96.10% for dextran 20 kDa. It is indicated that diphenyl ketone is a competitive diluent to prepare CA membranes with excellent performance via TIPS. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42669. [ABSTRACT FROM AUTHOR]

Ethanol and rapeseed oil are mixed in the presence of tributyl citrate, 2,5-dimethylfuran, 2-methylfuran, 2-methyl tetrahydrofuran, methyl tert butyl ether, ethyl tert butyl ether, FAME-rapeseed biodiesel, 1-heptanol, and 2-ethylhexyl nitrate, at 25 °C (298.15 K). All these additives come or can be obtained completely or partially from plants. The obtained ternary phase diagrams show a large domain of clear and homogeneous solutions and a liquid two-phase system due to the partial solubility of rapeseed oil and ethanol. All the tested additives have thus an evident cosolvent behavior for ethanol and rapeseed oil. In all the studied systems, the possible presence of nanostructures is checked with dynamic light scattering (DLS) and confirmed using static light scattering (SLS). In the system rapeseed oil/ethanol/1-heptanol, the presence of nanostructures is definitely established performing small-angle neutron scattering (SANS). The true geometry of these nanostructures could not be detected, but systematic conductivity measurements starting with the binary melt 1-heptanol/rapeseed oil in the presence of LiClO adding ethanol show clearly a continuous transition from ethanol-in-rapeseed oil to rapeseed oil-in-ethanol mixtures passing through a bicontinuous medium. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membranes were prepared via a thermally induced phase separation (TIPS) process using mixed diluent consisting of dibutyl phthalate (DBP) and dibutyl sebacate (DBS). The compatibility between PVDF and mixed diluent was predicted via the solubility parameter theory and verified by experimental results. The effects of mixed diluent composition on cloud point temperature, crystallization temperature, crystallinity, crystal phase and morphology of the membrane were investigated. As a result, as DBS mass fraction in mixed diluent increased, the cloud point temperature and the crystallinity increased, the crystal phase transformed from β phase to α phase and the morphology of the membrane cross-section changed from spherulitic structures to a bicontinuous structure. PVDF hollow fiber membranes were prepared successfully with the PVDF/DBP/DBS system via the TIPS method. The coagulant composition had a significant influence on the water permeability. When the dimethylacetamide (DMAc) content in the coagulant was 60%, the water permeability reached 877 l/m2·h, while the rejection rate to the particles with a size of 200-500 nm was above 95%. [ABSTRACT FROM AUTHOR]

While coarsening of spherical particles has been well documented, our understanding of coarsening of complex microstructures is still limited. The first step in developing a theory of coarsening of microstructures with complex morphologies is to study coarsening of microstructures that evolve self-similarly. In this paper, we examine the morphological evolution of a self-similar two-phase bicontinuous structure generated via nonconserved dynamics (i.e., motion by mean curvature) to elucidate the complex dynamics of coarsening. We find that the evolution proceeds with some interfaces evolving toward topological singularities (pinching) while the majority of interfaces flatten. These two processes were also illustrated through the evolution equation for the mean curvature, which has a term that depends solely on the local curvatures, as well as a term that is proportional to the surface Laplacian of the mean curvature. The first term causes an increase in the magnitude of the mean curvature, while the second term causes smoothing of the mean curvature in a manner similar to diffusion of chemical species on a surface. The second term causes a large dispersion in the values of the time derivative of mean curvature at various locations in the structure, characterized neither by the mean curvature nor the Gaussian curvature. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membranes were prepared via a thermally induced phase separation (TIPS) process using mixed diluent consisting of dibutyl phthalate (DBP) and dibutyl sebacate (DBS). The compatibility between PVDF and mixed diluent was predicted via the solubility parameter theory and verified by experimental results. The effects of mixed diluent composition on cloud point temperature, crystallization temperature, crystallinity, crystal phase and morphology of the membrane were investigated. As a result, as DBS mass fraction in mixed diluent increased, the cloud point temperature and the crystallinity increased, the crystal phase transformed from β phase to α phase and the morphology of the membrane cross-section changed from spherulitic structures to a bicontinuous structure. PVDF hollow fiber membranes were prepared successfully with the PVDF/ DBP/DBS system via the TIPS method. The coagulant composition had a significant influence on the water permeability. When the dimethylacetamide (DMAc) content in the coagulant was 60%, the water permeability reached 877 l/m²·h, while the rejection rate to the particles with a size of 200-500 nm was above 95%. [ABSTRACT FROM AUTHOR]

Abstract: The rheology of mixed κ-carrageenan/ι-carrageenan gels was investigated in the presence of 75 or 150 mM K+. The addition of ι-carrageenan to κ-carrageenan led to an initial weak increase of the Young's modulus. A maximum occurred at concentrations ratios close to 1:1, followed by a weak decrease at higher ι-carrageenan concentrations. When κ- and ι-carrageenan were mixed at a constant total polysaccharide concentration, a plateau of the Young's modulus and a clear local minimum in the fracture strain in both compression and extension were identified at ratios between 2:1 and 4:3 (ι:κ). At all other ratios, the expected strong increase of the Young's modulus and decrease of the fracture strain were observed with an increasing κ-carrageenan fraction. A weak maximum of the fracture stress in compression and extension was observed at ratios between 1:1 and 1:2 (ι:κ). The structural and rheological findings support segregative phase-separation of mixed carrageenan gels in the presence of K+. Phase separation could be promoted through curing of the gel network of ι-carrageenan at temperatures above the coil-to-helix transition of κ-carrageenan. [Copyright &y& Elsevier]

• We successfully prepared a Cu 55.4 Zr 35.2 Al 7.5 Y 1.9 bi-continuous nanoporous metallic glass with ligaments size of ∼20 nm. The mechanical properties and plastic deformation of nanoporous and solid metallic glasses have been studied using depth-sensing nanoindentation combined with electron microscopy characterization. • The nanoporous metallic glass has distinct mechanical properties and deformation behavior comparing to solid glass. It fails in transverse fracture under tension but becomes ductile under compression without any noticeable shear banding events. Irreversible plastic deformation has taken place well before the global yield point from partial unload compression. • We discovered a transition of deformation modes at a critical strain near 0.03. The global yielding in this nanoporous metallic glass obeys a universal scaling law of yielding in metallic glasses. The results provide intrinsic relations between classic Gibson-Ashby law and the universal scaling law in metallic glasses. • This nanoporous metallic glass has the highest yield stress comparing to crystalline nanoporous materials and it maintains a high strain hardening index under compression. The mechanical properties and plastic deformation of a Cu 55.4 Zr 35.2 Al 7.5 Y 1.9 nanoporous metallic glass (MG) have been studied using depth-sensing nanoindentation combined with electron microscopy characterization. The nanoporous MG exhibits an initial relative density of 50.9% and a bicontinuous structure with 20.84 ± 1.49 nm-diameter interconnecting ligaments. It is brittle in tension, whereas it has significant homogeneous plasticity under compression. It has a hardness of 0.67 ± 0.06 GPa and Young's modulus of 14.72 ± 0.74 GPa from nanoindentation. While under tensile and compression, it has a yield strength of 0.22 to 0.23 GPa and an effective modulus of 10.37 ± 0.99 GPa. The discrepancy between the moduli is caused by irreversible shear transformation zone (STZ) plasticity that takes place well ahead of the yield point. The deformation in the nanoporous MG begins with both elastic and plastic bending in ligaments and transfers to plastic uniaxial deformation in ligaments at a critical strain near 0.03, at which a significant change in stiffness is observed. The yielding stress follows the universal scaling law predicted by the critical-like behavior in glassy systems. The strength to modulus ratio is well maintained in this nanoporous MG and is higher than the porous crystalline alloys. Our experimental study clarifies the fundamental failure mechanism and deformation behavior in nanoporous MGs. [ABSTRACT FROM AUTHOR]

Abstract: The phase behavior of polydisperse ABA triblock copolymers is studied using dissipative particle dynamics simulations, focusing on the emergence and property of bicontinuous structures. Bicontinuous structures are characterized by two separate, intermeshed nanoscopic domains extending throughout the material. The connectivity of polymeric bicontinuous structures makes them highly desirable for many applications. For conventional monodisperse diblock and triblock copolymers, regular bicontinuous structures (i.e., gyroid and Fddd) can be formed over a narrow composition window of 3%. We demonstrate that the composition window for the formation of bicontinuous structures can be regulated by designed polydispersity distributions of ABA triblock copolymers. In particular, introducing polydispersity in both A and B blocks can lead to a significant enhancement of the composition window of bicontinuous structures with both continuous A and B domains. The mechanism of the bicontinuous structure enhancement is elucidated from the distribution of the long and short blocks. Furthermore, it is shown that the polymeric bicontinuous structures from polydisperse ABA triblock copolymers possess good continuity throughout the sample, making them ideal candidates for advanced applications. [Copyright &y& Elsevier]

Poly(vinylidene fluoride) (PVDF) membranes possessing interconnected bicontinuous structures with superior mechanical properties and improved hydrophilicity were obtained from PVDF/ N, N-dimethylacetamide (DMAc)/Tween 80/water systems via non-solvent induced phase separation (NIPS) with 60 °C and ambient temperature casting solution. Tween 80/HO mixtures were adopted as dopant; water/ethanol (50:50, mass ratio) and ethanol were chosen as coagulants. The effects of process parameters in terms of variations in dopant contents, casting solution temperatures, and coagulant compositions on the phase inversion process and performance of the resultant membranes were investigated. During the demixing process, water diffused from the interior of Tween 80 reverse micelles, resulting in an accelerated precipitation rate and surface segregation process of the polar head groups of Tween 80. The high temperature of the casting solution contributed to enhancing the diffusion rate of liquid-liquid demixing on crystallization. The coagulant compositions changed the liquid-liquid and solid-liquid demixing dynamics of the casting solutions. Ethanol coagulant contributed to crystallization of PVDF/DMAc/Tween 80/water systems prior to liquid-liquid demixing. This delayed demixing process favored the formation of porous foliage-type top structures with fibril or lath bicontinuous fine structure of membrane bulk, increasing flux, and significant hydrophilicity improvement. Casting solutions in water/ethanol coagulant exhibited a less delayed demixing process with both liquid-liquid demixing and crystallization, resulting in formation of fine structure in the form of strings or stripes and limited hydrophilicity improvement. The predominant typical α- and β-type crystallinity in PVDF was attributed to the existence of dopants, the high temperature of the casting solution, and water/ethanol coagulant. This was consistent with the superior mechanical properties of the corresponding PVDF membrane. The newly developed hydrophilic PVDF membranes with superior mechanical properties and low-fouling of bovine serum albumin (BSA) are anticipated to be suitable not only for wastewater treatment, but also for bioseparation. [ABSTRACT FROM AUTHOR]

Abstract: A mixed diluent composed of γ-butyrolactone (γ-BL) and dioctyl phthalate (DOP) was employed for preparing PVDF microporous membrane via TIPS method. The relation equations expressing the quantitative relationship between interaction parameter and phase separation temperature were deduced based on Flory–Huggins equation and solubility parameter theory. The unknown constants in the relation equations were solved out by fitting the binodal curve with cloud points in phase diagram. The binodal curves of PVDF/mixed diluent systems with different diluent compositions were calculated according to the relation equations. The compositions possible to yield bicontinuous structure inside microporous membrane were predicted in phase diagram. Finally, the hollow fiber membrane with interconnected sponge-like structures was prepared successfully from the predicted system (PVDF 12.74%, DOP 58.44%). The DCMD performances of the fabricated hollow fiber membranes were investigated with 3.5wt% NaCl solution. The permeate flux of the membrane achieved 51.5kg/m2 h with the NaCl rejection of 99.99% at the feed temperature of 90°C. As a result, this prediction method is effective in constructing the polymer/mixed diluent system which is used for preparing MD hollow fiber membrane in TIPS process. [Copyright &y& Elsevier]

Abstract: Rigid methacrylate-based polymer monoliths with well-defined macropores have been synthesized from glycerol 1,3-dimethacrylate (GDMA) and trimethylolpropane trimethacrylate (Trim) by organotellurium-mediated living radical polymerization. In each system, poly(ethylene oxide) induced spinodal decomposition with the progress of polymerization of GDMA or Trim. Well-defined macroporous structure can be tailored by fixing the bicontinuous structure by the sol–gel transition. Both polymer monoliths possessed macropores with narrow size distributions and the macropore size can be controlled simply by varying the amount of poly(ethylene oxide). Starting from GDMA, polymer monoliths with unimodal macropores can be obtained due to the collapse of micro- and mesopores, which were originally embedded in macropore skeletons, by large shrinkage during drying. In contrast, starting from Trim, the obtained polymer monoliths include not only macropores but also micro- and mesopores, which lead to high specific surface area (470 m2 g−1), owing to the higher crosslinking density. [Copyright &y& Elsevier]

Abstract: In this study, a bicontinuous structure of poly(methyl methacrylate) (PMMA) membrane was obtained via wet immersion method by coagulating PMMA/1,4-dioxane casting film into alcohol bath. Freeze-dried method was utilized to investigate the evolution of membrane structure at various coagulation times. The FTIR-microscope, scanning electronic microscope (SEM), ternary phase diagram as well as light transmission were used to investigate the formation and structure evolution mechanism of PMMA membrane. The results show that the bicontinuous structure can be formed on the top surface of PMMA membrane as contacted the PMMA/1,4-dioxane casting film with n-propanol only 2s. Furthermore, it also can be found that as increasing the immersion time in n-propanol bath over than 1.5min, the bicontinuous structure would be broken up to form nodules morphology due to capillarity effect, or led to a matrix/disperse domain morphology by coalescence effect. The analysis of FTIR-microscopy shows that the PMMA polymer concentration in the top layer of nascent membrane was decreased as immersed the casting film into n-propanol bath. The lower PMMA polymer concentration in the top layer could cause the composition path entered into the unstable region, resulting in the formation of bicontinuous structures. [Copyright &y& Elsevier]

Abstract: Dielectric relaxation in binary mixtures containing particles or lamellae with complex geometry has been simulated within the quasielectrostatic approximation by a three-dimensional finite-difference method. The method was tested using simple models corresponding to water-in-oil (W/O) and oil-in-water (O/W) emulsions with volume fraction P up to 0.5. The dielectric spectra calculated by the finite difference method agreed with those expected from Wagner''s equation at and approached those from Hanai''s equation at . This method was applied to more complicated binary mixtures of oil and water: a bicontinuous cubic structure, a suspension of particles with projections, and a planar bilayer with a rippled or interdigitated interface. The bicontinuous phase that is supposed to appear near the transition between W/O and O/W emulsions showed dielectric properties similar to those of the O/W emulsion. The undulation of the particle surface and the interface of the planar bilayer affected all parameters of dielectric relaxation, especially the relaxation intensity. [Copyright &y& Elsevier]

Despite substantial progress in porous materials over past years, controllable preparation of conductive polymers (CPs) with continuous large pores is challenging, which are important for diverse applications, including energy storage, electrocatalysis, and biological separations. Here, we develop an unprecedented ordered bicontinuous mesoporous PPy cubosomes (mPPy-cs) using a soft-template strategy, resulting in ultralarge pores of ∼45 nm and high specific surface area of 69.5 m 2 g -1 . Along with their unique characteristics of adjustable surface charges and sensitivity to pH, mPPy-cs exhibited a near quantitative adsorption of albumin within 30 min, enabling efficient separation from immunoglobulin G, a typical inclusion in commercial albumin products. Moreover, the absorbed albumin could be further released in a controlled manner by lowering the pH. This work provides a feasible strategy for bottom-up construction of CPs with tailored pore sizes and nanoarchitectures, expected to attract significant attention to their properties and applications.

The dielectric relaxation spectra of the non-aqueous ionic liquid (IL) microemulsions composed of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF 4 ])/p-(1,1,3,3-tetramethylbutyl)phenoxypolyoxyethyleneglycol (TX-100)/toluene were obtained, the measured frequency is between 1 MHz and 3 GHz. A unique dielectric relaxation located at 10–100 MHz was observed. The direct current (dc) conductivity data were obtained from the total dielectric loss. Near the percolation transition, weight fraction dependence of dc conductivity and static dielectric constant, frequency dependence of permittivity and loss angle all suggest that static percolation occurs in this hydrophilic IL microemulsion. Phase boundaries of IL-in-toluene (IL/O), bicontinuous (B.C.) and toluene-in-IL (O/IL) subregions were determined by the inflection points in the dependent curve of relaxation parameters varied with weight fraction. The mechanism of this dielectric relaxation is attributed to the interfacial polarization of droplets by analyzing relaxation time with Maxwell-Wagner theory. The phase parameters, which reflect the interior properties of the spherical dispersed particle, were calculated by Hanai theory. The dependence of phase parameters on the variation of sample composition was properly explained. For O/IL subregion, the continuous phase should be an IL/TX-100 binary solvent rather than the pure IL. For IL/O subregions, a certain amount of toluene was dissolved in the droplets. The dielectric properties of three subregions, namely, IL-in-toluene, bicontinuous and toluene-in-IL for non-aqueous ionic liquid microemulsion [bmim][BF 4 ]/TX-100/toluene. [Display omitted] [ABSTRACT FROM AUTHOR]