Development of 3D bicontinuous metal-intermetallic composites through subsequent alloying process after liquid metal dealloying

This study presents a novel process for the fabrication of metal-intermetallic composites with a 3D bicontinuous structure, achieved through a combination of liquid metal dealloying(LMD) and subsequent alloying. Initially, porous Ti structures are produced using the LMD process, followed by immersion in a molten Mg-3Al(wt%) metal. Due to the higher thermodynamic miscibility of Al with Ti compared to Mg, the concentration of Al in the Ti matrix increases as the immersion time increases. This results in a sequential phase transition within the Ti matrix: α-Ti → Ti_(3)Al → Ti Al. The phase transition considerably affects the hardness and strength of the composite material,with the Mg-Ti_(3)Al-Ti Al composite exhibiting a maximum hardness nearly twice as high as that of the conventional Mg-Ti composite. This innovative process holds potential for the development of various bicontinuous metal-intermetallic composites.

Ordered Bicontinuous Network Structures Regulated by Orientational Interactions in a Rod-Coil Block Copolymer

The rich phase behavior of block copolymers(BCPs)has drawn great attention in recent years.However,the double diamond(DD)phase is rarely obtained because of the competition between the minimization of interfacial energy and packing frustration.Here,a rod-coil BCP containing mesogen-jacketed liquid crystalline polymer is designed to acquire ordered bicontinuous network nanostructures.The reduction of internal energy originating from the orientational interaction among the rod blocks can compensate for the free energy penalty of packing frustration to stabilize the DD structure.The resulting BCP can also experience lamellae-to-DD and double gyroid-to-lamellae transitions by changing the annealing temperature.These results make the rod-coil BCP an excellent candidate for the self-assembly of ordered network structures,demonstrating great potential in nanopatterning and metamaterials.

Polymerization-Induced Self-Assembly for the Preparation of Poly(N,N-dimethylacrylamide)-b-Poly(4-tert-butoxystyrene-co-pentafluorostyrene)Particles with Inverse Bicontinuous Phases

Main observation and conclusion Polymerization-induced self-assembly(PISA)is an effective method to prepare block copolymer(BCP)particles with various morphologies.However,BCPs with inverse bicontinuous phase structure have been rarely prepared via PISA.Herein,we report the preparation of particles.

Double diamond structured bicontinuous mesoporous titania templated by a block copolymer for anode material of lithium-ion battery

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 I4_(1)/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 m^(2)·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.

Efficient Access to Inverse Bicontinuous Mesophases via Polymerization-Induced Cooperative Assembly

Polymerization-induced cooperative assembly(PICA)is reported to efficiently access inverse bicontinuous mesophases within particles consisting of amphiphilic block copolymers(BCPs)and solvophobic copolymers.Reversible addition-fragmentation chain transfer(RAFT)dispersion alternating copolymerization of styrene and pentafluorostyrene is conducted in 2%v/v toluene/ethanol by simultaneously using poly(N,N-dimethylacrylamide)(PDMA29)as a macromolecular chain transfer agent(macro-CTA)and small molecule CTA.

ROD-LIKE AGGREGATES FROM POLYSTYRENE-b-POLY(4-VINYLPYRIDINE)-b-POLYSTYRENE TRIBLOCK COPOLYMER IN AQUEOUS MEDIA

The rod-like assembly from BAB block copolymer with hydrophilic middle block A in aqueous solution was described. The copolymer used is polystyrene (PS)39-b-poly(4-vinylpyridine)(P4VP)98-b-PS39 (the subscripts are the average polymerization degree of corresponding blocks) triblock copolymer with Mw/Mn = 1.15. The aggregates were characterized by transmission electron microscopy and atomic force microscopy. The dependence of rod-like aggregate formation on solvents, pH, and polymer concentrations was investigated. The rod-like aggregates were formed when using dioxane as initial solvent, while spherical micelles were formed using DMF. Elevating pH values from 4 to 5 to 7 and decreasing initial copolymer concentrations from 1.5 wt% to 1.0 wt% to 0.5 wt% were favorable for the formation of well-defined rod-like aggregates. In addition, the bicontinuous rods and lamellae were observed when preparing colloid solutions in appropriate conditions.

Bifunctional SiC/Si_(3)N_(4) aerogel for highly efficient electromagnetic wave absorption and thermal insulation

SiC ceramics are attractive electromagnetic(EM)absorption materials for the application in harsh environment because of their low density,good dielectric tunable performance,and chemical stability.However,the performance of current SiC-based materials to absorb EM wave is generally unsatisfactory due to poor impedance matching.Herein,we report ultralight SiC/Si3N4 composite aerogels(~15 mg·cm^(−3))consisting of numerous interweaving SiC nanowires and Si3N4 nanoribbons.Aerogels were prepared via siloxane pyrolysis and chemical vapor reaction through the template method.The optimal aerogel exhibits excellent EM wave absorption properties with a strong reflection loss(RL,−48.6 dB)and a wide effective absorption band(EAB,7.4 GHz)at a thickness of 2 mm,attributed to good impedance matching and multi attenuation mechanisms of waves within the unique network structure.In addition,the aerogel exhibits high thermal stability in air until 1000℃and excellent thermal insulation performance(0.030 W·m^(−1)·K^(−1)).These superior performances make the SiC/Si_(3)N_(4) composite aerogel promising to become a new generation of absorption material served under extreme conditions.

Nanoscale 3D ordered polymer networks

Structures having nanoscale 3 D geometries are valuable as multifunctional materials, where multi-continuous microphases can synergistically influence mechanical, optical, transport and other properties. Such very high interface surface to volume ratio structures occur in a variety of materials including natural materials such as butter fly wings and sea urchin exoskeletons and in synthetic self-assembled structures such as surfactant/water systems and block polymers. Quantitative morphological characterization of such complex geometric structures is quite challenging. Unit cell sizes range from 10–300 nm with corresponding feature sizes on the 2–50 nm scale. Since these nanoscale network structures are bicontinuous, when one constituent is removed, the structure is still self supporting. Removal of one component produces a nanoporous material that may be in-filled with another component, or the surfaces of the nanopores can be coated with ultra-thin layers by atomic layer deposition to offer multifunctional capabilities. Due to the ability to individually tailor the properties of the network(s) and matrix,for example, to create strong dielectric or impedance contrast, such spatially periodic structures are excellent for the interference of waves(electromagnetic for photonic applications and acoustic for phononic applications) that can lead to bandgaps and hence the control of wave propagation in the material. This mini-review will focus on networks formed by bottom up self assembly of block polymers. In addition to structural issues, we emphasize the special physical properties related to bi-or tri-continuous networks.

Suzuki Reactions in Water Catalyzed by an Active and Reus- able PMO-Type Pd（ll） Organometal Catalyst with Cage-Like Mesoporous Structure

A novel Pd（ll） organometal catalyst with three-dimensional （3D） cage-like la3d cubic mesoporous structure and high surface area was prepared. In comparison with the corresponding catalyst with two-dimensional （2D） P6mm hexagonal mesoporous structure, the as-prepared catalyst exhibited higher activities in the water-medium Suzuki coupling reactions owing to the diminished diffusion limit. It showed comparable efficiencies with the Pd（PPh3）2C12 homogeneous catalyst and could be easily recycled and reused for five times without significant loss of activity.