Tunable Microstructure Research Articles

Engineering Emulsion Gels as Functional Colloids Emphasizing Food Applications: A Review.

Gels are functional materials with well-defined structures (three-dimensional networks) assembled from the dispersed colloids, and capable of containing a large amount of water, oil, or air (by replacing the liquid within the gel pores), known as a hydrogel, oleogel, and aerogel, respectively. An emulsion gel is a gelled matrix filled with emulsion dispersion in which at least one phase, either continuous phase or dispersed phase forms spatial networks leading to the formation of a semisolid texture. Recently, the interest in the application of gels as functional colloids has attracted great attention in the food industry due to their tunable morphology and microstructure, promising physicochemical, mechanical, and functional properties, and superior stability, as well as controlled release, features for the encapsulated bioactive compounds. This article covers recent research progress on functional colloids (emulsion gels), including their fabrication, classification (protein-, polysaccharide-, and mixed emulsion gels), and properties specifically those related to the gel-body interactions (texture perception, digestion, and absorption), and industrial applications. The emerging applications, including encapsulation and controlled release, texture design and modification, fat replacement, and probiotics delivery are summarized. A summary of future perspectives to promote emulsion gels' use as functional colloids and delivery systems for scouting potential new applications in the food industry is also proposed. Emulsion gels are promising colloids being used to tailor breakdown behavior and sensory perception of food, as well as for the processing, transportation, and targeted release of food additives, functional ingredients, and bioactive substances with flexibility in designing structural and functional parameters.

Direct synthesis of P/O-enriched pitch-based carbon microspheres from a coordinated emulsification and pre-oxidation towards high-rate potassium-ion batteries

Pitch-based soft carbons, with tunable microstructure and low cost, hold great potential as anodes for potassium-ion batteries (PIBs). However, the sluggish storage kinetics and unsatisfying cycle life hinder their practical applications. In addition, low softening point pitch has been seldom used to fabricate carbon microspheres due to its thermoplasticity. Herein, P and O enriched pitch-based carbon microspheres were directly synthesized via coordinated emulsification and pre-oxidation, and followed carbonized with NaH2PO2. This template-free method can avoid the coalescence of the coal tar pitch without extra post-stabilization. And NaH2PO2 acts as a P doping source and generates modest mesopores. The prepared P and O enriched carbon microspheres manifest a high P content of 4.0 at%, expanded interlayer distance of 0.401 nm, and abundant reversible K+ storage sites. As a result, it delivers considerable discharge capacity of 352 mAh g−1, impressive rate capacity of 114 mAh g−1 at 5 A g−1, and long lifespan of 181 mAh g−1 at 1 A g−1 after 1000 cycles. The present work develops a new avenue for heteroatoms doped carbon microspheres to innovative potassium storage and beyond.

Ultrafast high-temperature heating in air

Ultrafast high-temperature heating methods based on the Joule heating of carbon heaters can dramatically shorten the time required for material synthesis/sintering. However, commonly used porous carbon heaters cannot provide stable high temperatures in air, limiting their applicability to the processing of atmosphere-sensitive materials. In this study, we present a novel configuration for ultrafast high-temperature heating in air using commercial graphite paper. This configuration enables stable high temperatures of ~1330–2230 °C in air, on the time-scale of minutes, and ultrafast heating rates, reaching ~104 oC/min. We describe the mechanism behind the excellent performance of our proposed configuration, and further demonstrate its flexibility and controllability by considering ultrafast high-temperature sintering of ZnO ceramics with tunable microstructures using different heating profiles. Our configuration provides a complementary approach to simplifying the ultrafast high-temperature heating process, reducing costs, and meeting the requirements of synthesis/sintering in air.

ECM-inspired peptide dendrimer microgels with human MSCs encapsulation for systemic lupus erythematosus treatment

Mesenchymal stem cells (MSCs) transplantation is an emerging and attractive therapy for immune dysregulation diseases like systemic lupus erythematosus (SLE). However, its application is hindered by short in vivo persistence and poor cellular survival after injection. Here, inspired by the native extracellular matrix (ECM) composition, we presented a novel peptide dendrimer-based microgel encapsulated with MSCs via a microfluidic approach for SLE treatment. By varying microfluidic parameters, monodisperse microgels with tunable diameters, porous microstructures, mechanical stiffness, and immune-isolation potential could be precisely achieved. As the water polymerization environment and ECM like components, the resultant microgels exhibited minimal toxicity in vivo and in vitro. We have also demonstrated that the MSCs encapsulated microgels could significantly increase the cellular bioactivity, enhance the immunomodulatory function, and attenuate disease symptoms in MRL/lpr mice. These results indicate the bioinspired microgels with MSCs encapsulation have potential clinical values in the treatment of SLE and other immune dysregulation diseases.

Preparation of size-controlled all-lignin based carbon nanospheres and their electrochemical performance in supercapacitor

Lignin, as the second most abundant biomass material in nature, is regarded as an ideal carbon precursor due to the presence of a larger amount of aromatic ring structural unit. Carbon nanospheres, as one of the vital members of carbon materials, are promising advanced materials for various areas. However, lignin-based carbon spheres suffered a complex fabrication process, high crosslinking between spheres, and non-adjustable micron size. Here, all-lignin based carbon nanospheres (LCNS) with tunable size and microstructure were prepared via self-assembly, stabilization treatment, and carbonization. Subsequently, their applications in supercapacitor electrode material were investigated. The results showed that the monodispersed, ordered, and regular carbon nanospheres could be constructed. The size of LCNS could be tuned ranging from 256 to 416 nm via changing the initial concentration of lignin between 0.5 and 2 mg mL−1. The as-prepared LCNS provided a specific surface area between 652 and 736 m2 g−1 through adjusting the size and microstructure. When the LCNS was assembled into the electrochemical capacitor, the LCNS electrode materials exhibited a high specific capacitance of 147 F g−1. Additionally, the LCNS-based symmetrical capacitor showed an ultralow characteristic relaxation time (0.86 s) and long cycle stability for 10,000 cycles. The capacitance properties could be regulated via reconciling the size of nanospheres and microstructure induced by carbonization temperature. The governable capacitance performance indicates that the as-prepared LCNS should be a promising candidate material for energy storage.

Functional graphene paper from smart building to sensor application

Graphene papers (GPs) have revolutionized the area of sensors toward low-cost, user-friendly and wearable/portable owning to their unique properties such as scalable production capacity, tunable microstructure, and extraordinary mechanical flexibility. They can be utilized as versatile building blocks by regulating their architectures to enhance various properties like electronic property, thermal conductivity and mechanical strength. Furthermore, thanks to the excellent compatibility, GPs as support materials are able to associate with other materials through various interaction forces to realize specific functionalization. With the impressive performances mentioned above, lots of smart devices like flexible sensors, advanced wearable/stretchable electronics, and high-performance point-of-care analytical devices are continually and rapidly being developed. Herein, this review aims at offering a critical engineering insight from smart architecture of macroscopic GPs to sensor application, with the emphasis on purpose-driven specific dual-mode functionalization (structural functionalization and foreign materials functionalization). We summarize the multiple possibilities to functionalize graphene and its derivative based papers/films/membranes. The sensing application of GPs in human health management, food contaminant inspection, and environmental monitoring is evaluated just before leading to our conclusions and perspectives.

Synergetic Dielectric and Magnetic Losses of a Core-Shell Co/MnO/C Nanocomplex toward Highly Efficient Microwave Absorption.

High-performance microwave-absorbing materials (MAMs) derived from metal-organic frameworks (MOFs) have attracted considerable attention due to their tunable chemical composition and microstructure. In this contribution, a core-shell-structured Co/MnO/C nanocomplex was prepared using a CoMn-MIL MOF by a facile hydrothermal synthesis and subsequent pyrolysis process. The optimal microwave absorption (MA) property of the as-prepared Co/MnO/C nanocomplex was achieved by the regulation of the Co2+/Mn2+ molar ratio. The minimum reflection loss (RLmin) of the Co/MnO/C-31 nanocomplex was low to -55.0 dB at 16.2 GHz with a thickness of 1.49 mm, and the effective absorption bandwidth (EAB) was high to 5.95 GHz (12.05-18 GHz) at a thickness of 1.8 mm. The mixed-metal nanocomplex with the core-shell structure exhibited outstanding MA performance, corresponding to the synergetic effect of the magnetic and dielectric loss. It provides a high efficiency strategy for rendering low reflection loss and broad EAB to high-performance MAMs.

Scalable Manufacturing of Ultralight, Multifunctional Cellulose Nanofiber Aerogel Sphere with Tunable Microstructure

Scalable Manufacturing of Ultralight, Multifunctional Cellulose Nanofiber Aerogel Sphere with Tunable Microstructure

Strength-Ductility Synergy in High Entropy Alloys by Tuning the Thermo-Mechanical Process Parameters: A Comprehensive Review.

The strength–ductility trade-off is an eminent factor in deciding the mechanical performance of a material with regard to specific applications. The strength–ductility synergy is generally inadequate in as-synthesized high entropy alloys (HEAs); however, it can be tailored owing to its tunable microstructure and phase stability. Thermo-mechanical processing (TMP) allows the microstructure to be tailored to achieve desired strength–ductility combination. The additional attribute is evolution of texture, which also significantly influences the mechanical properties. This review presents a critical insight into the role of TMP to achieve superior strength–ductility symbiosis at room temperature in single-phase (FCC, BCC) and multiphase HEA. The role of overall processing strategy of HEAs encompassing rolling and subsequent annealing in relation to the evolution of microstructure and texture in have been discussed. Recently practiced severe plastic deformation processes have also shown promise in improving the strength–ductility combination. The relevance of these processes in the processing of HEAs has also been analysed. At the end, futuristic approaches have been elaborated to enable efficient as well as hassle-free process towards achieving the proficiency of strength–ductility in HEAs.

Polymer-directed crystallization of HMX to construct nano-/microstructured aggregates with tunable polymorph and microstructure

Multi-scale structural control of the high explosive HMX was achieved by a polymer-directed crystallization strategy. For the first time, HMX spherulites that exhibited a “Maltese cross” extinction pattern under crossed polarizers were obtained.

Effect of Freezing Process on the Microstructure of Gelatin Methacryloyl Hydrogels.

Gelatin methacryloyl (GelMA) hydrogels have aroused considerable interests in the field of tissue engineering due to tunable physical properties and cell response parameters. A number of works have studied the impact of GelMA concentration, photo-initiator concentration, methacrylic anhydride (MA) concentration, cooling rate and temperature gradient on GelMA hydrogel generation, but little attention has been paid to the effect of the freezing temperatures and freezing time of GelMA prepolymer solution during preparation. In this study, GelMA hydrogels were synthesized with different freezing temperatures and time. It was found that the lower freezing temperatures and longer freezing time caused smaller pore sizes that realized higher cell viability and proliferation of MC3T3-E1 cells. The results showed that tunable microstructure of GelMA could be achieved by regulating the freezing conditions of GelMA, which provided a broad prospect for the applications of GelMA hydrogels in tissue engineering.

Silk fibroin-decorated with tunable Au/Ag nanodendrites: A plastic near-infrared SERS substrate with periodic microstructures for ultra-sensitive monitoring of lactic acid in human sweat

The flexible and plastic near-infrared surface-enhanced Raman spectroscopy (NIR-SERS) substrate, with efficient tunable surface microstructures for probe molecular detection on irregular targets, has great potential for ultra-sensitive monitoring in real-world scenarios. Herein, we propose an interesting 785 nm laser-excited plastic SERS substrate based on the silk fibroin fibers (SFF) decorated with multiple-branched Au/Ag nanodendrites (NDs). Compared with the original smooth flexible substrate, the further constructed plastic SFF-Au/Ag NDs with concave pyramid surface microstructures provides a relatively higher NIR-SERS activity at bottom of the inward concave region. Moreover, the enhanced NIR-SERS activity is also highly related to the content of Au/Ag NDs in the hybrid flexible substrate. The maximal NIR-SERS signal intensity can be realized at the content of 0.15 wt% Au/Ag NDs in the SFF-Au/Ag NDs, which is about 8-fold enhancement compared to that obtained at the content of 0.01 wt%. Then, the molecular detection limits of crystal violet (CV) and 4-mercaptobenzoic acid (4-MBA) are calculated about 10−15 and 10−13 M, respectively, reaching the ultra-sensitive requirements of NIR-SERS trace detection. Moreover, the substrate can detect lactic acid (LA) molecules with a concentration as low as 10−9 M, and can effectively reflect slight LA fluctuation in human sweat, providing a basis for the realization of ultra-sensitive NIR-SERS health monitoring.

Ionic liquid microemulsion mediated synthesis of Pt/TiO2 nanocomposites for ammonia borane hydrolysis

Tunable microstructure of microemulsion self-assembly systems has the prominent application as nanoreactors in reaction processes. Scientific and technological interest in microemulsions derived from the confinement effect of polar or nonpolar domains for hydrophilic/hydrophobic molecules. Benefiting from the tunable nature, ionic liquids-based self-assembly systems have been demonstrated as a versatile platform for catalytic reaction, drug delivery, functional materials fabrication and among others. In this work, ionic liquids microemulsions were designed by using ionic liquids as apolar phase and surfactant. The phase equilibrium and microstructure were studied through phase diagram, conductivity method and dynamic light scattering. Ionic liquids-in-water microemulsions were proposed as nanoreactor for fabrication of nanosized platinum/titanium dioxide composites. The size, morphology and catalytic performance can be tuned by the microemulsion structure through its confinement effect. The hydrolysis of ammonia borane catalyzed by these composites exhibits better catalytic activity with higher turnover frequency and lower activation energy of the reaction. It is believed that the nanoreactors constructed from versatile ionic liquids will provide new guidance in designing advanced scientific applications.

N-alkylation briefly constructs tunable multifunctional sensor materials: Multianalyte detection and reversible adsorption

SummaryA series of N-alkyl-substituted polybenzimidazoles (SPBIs), synthesized by simple condensation and N-alkylation, act as functional materials with tunable microstructures and sensing performance. For their controllable morphologies, the formation of nano-/microspheres is observed at the n(RBr)/n(PBI) feed ratio of 5:1. Products with different degrees of alkylation can recognize metal ions and nitroaromatic compounds (NACs). For example, SPBI-c, obtained at the feed ratio of 1:1, can selectively detect Cu2+, Fe3+, and NACs. By contrast, SPBI-a, obtained at the feed ratio of 0.1:1, can exclusively detect Cu2+ with high sensitivity. Their sensing mechanisms have been studied by FT-IR spectroscopy, SEM, XPS, and DFT calculations. Interestingly, the SPBIs can adsorb Cu2+ in solution and show good recyclability. These results demonstrate that polymeric materials with both sensing and adsorption applications can be realized by regulating the alkylation extent of the main chain, thus providing a new approach for the facile synthesis of multifunctional materials.

Effect of alloying element on microstructure, mechanical property, and oxidation resistance of Zr─Me─C (Me═Si/Y) coatings

AbstractAccident‐tolerant fuels (ATFs) are proposed to provide improved safety response to a loss of coolant accident (LOCA) scenario while maintaining good operational characteristics under normal conditions. In this work, Zr─Me─C (Me═Si or Y) was proposed as candidate coatings for ATF applications. The influence of Si and Y with varied concentration on microstructural evolution, mechanical property, and oxidation resistance of Zr─Me─C coatings were investigated. Based on combined results of X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy, it was found that Si or Y doped ZrC0.55 coatings presented tunable composition and microstructure. Improved air oxidation and spallation resistance were achieved with the incorporation of Me atoms, attributing to the formation of SiO2 and ZrSiO4 and/or the stabilization of zirconia. Under a simulated LOCA condition, decreased weight gains of 13.6 at.% Si and 22.5 at.% Y coated Zry‐4 alloys were achieved. nc‐ZrSiC/nc‐ZrSi (13.6 at.% Si) coating exhibited enhanced mechanical property and oxidation resistance in both high‐temperature air and LOCA conditions, which could be regarded as potential candidate for the applications in ATFs.

Soft template assisted hydrothermal synthesis of phosphorus doped porous carbon spheres with tunable microstructure as electrochemical nanozyme sensor for distinguishable detection of two flavonoids coupled with derivative voltammetry

• Phosphorus-doped hierarchically porous carbon nanosphere (PVP-P-PCS) was obtained. • PVP-P-PCS was prepared by soft template assisted hydrothermal method from xylan. • PVP-P-PCS possessed coexisted micropores, mesopores and macropores. • PVP-PCS showed intrinsic oxidase-like characteristic and high sensitivity. • Distinguishable detection of two flavonoids achieved with derivative voltammetry. A variety of phosphorus doped porous carbon spheres (P-PCSs) with tunable microstructure are facilely prepared by hydrothermal method using xylan as a carbon source, phosphoric acid as an activator and dopant, surfactants as soft templates. Surfactants are beneficial to the development of pore structure and the decrease of particle size. In particular, the introduction of polyvinylpyrrolidone (PVP) facilitates the formation of hierarchically porous structure and nanoscale dimension. The activation of phosphoric acid can improve the graphitization degree, enrich the surface oxygen-containing groups, realize phosphorus doping, and increase the specific surface area. The prepared PVP-P-PCS as a highly conducting electrocatalyst with well dispersed nano-sized spherical morphology of 50–150 nm, large specific surface area of 1558.14 m 2 /g and hierarchical porosity with coexisted micropores, mesopores and macropores, displays enhanced current responses of about 55-fold enhancement for luteolin and 52-fold enhancement for baicalin compared with bare GCE, intrinsic oxidase-like (nanozyme) characteristics, excellent electrocatalytic ability for luteolin with a low limit of detection (LOD) of 0.77 nM in linear ranges of 0.05–1 μΜ, and baicalin with a LOD of 3.3 nM in linear range of 0.05–1 μM. First-order derivative voltammetry is selected for realizing distinguishable determination of two flavonoids, which demonstrates satisfactory results in the practical application.

Nanoparticles exploring the macroscopic world

Nanoparticles exploring the macroscopic world

Diversifying Composition Leads to Hierarchical Composites with Design Flexibility and Structural Fidelity.

Although significant progress has been made in the self-assembly of nanostructures, present successes heavily rely on precision in building block design, composition, and pair interactions. These requirements fundamentally limit our ability to synthesize macroscopic materials where the likelihood of impurity inclusion escalates and, more importantly, to access molecular-to-nanoscopic-to-microscopic-to-macroscopic hierarchies, since the types and compositions of building blocks vary at each stage. Inspired by biological blends and high-entropy alloys, we hypothesize that diversifying the blend's composition can overcome these limitations. Increasing the number of components increases mixing entropy, leading to the dispersion of different components and, as a result, enhances interphase miscibility, weakens the dependence on specific pair interactions, and enables long-range cooperativity. This hypothesis is validated in complex blends containing small molecules, block copolymer-based supramolecules, and nanoparticles/colloidal particles. Hierarchically structured composites can be obtained with formulation flexibility in the filler selection and blend composition. It is worth noting that, by adding small molecules, we can solve the size constraint that plagues traditional block copolymer/nanoparticle blends. Detailed characterization and simulation further confirm that each component is distributed to locally mediate unfavorable interactions, cooperatively mitigate composition fluctuations, and retain structural fidelity. Furthermore, the blends have sufficient mobility to access tunable microstructures without compromising the order of the nanostructure. Besides establishing a kinetically viable pathway to release current constraints in the composite design and to navigate uncertainties during structure formation over multiple length scales, the present study demonstrates that entropy-driven behaviors can be realized in systems beyond high-entropy alloys despite inherent differences between metal alloys and organic/inorganic hybrids.

Tricomponent Supramolecular Multiblock Copolymers with Tunable Composition via Sequential Seeded Growth

AbstractSynthesis of supramolecular block co‐polymers (BCP) with small monomers and predictive sequence requires elegant molecular design and synthetic strategies. Herein we report the unparalleled synthesis of tri‐component supramolecular BCPs with tunable microstructure by a kinetically controlled sequential seeded supramolecular polymerization of fluorescent π‐conjugated monomers. Core‐substituted naphthalene diimide (cNDI) derivatives with different core substitutions and appended with β‐sheet forming peptide side chains provide perfect monomer design with spectral complementarity, pathway complexity and minimal structural mismatch to synthesize and characterize the multi‐component BCPs. The distinct fluorescent nature of various cNDI monomers aids the spectroscopic probing of the seeded growth process and the microscopic visualization of resultant supramolecular BCPs using Structured Illumination Microscopy (SIM). Kinetically controlled sequential seeded supramolecular polymerization presented here is reminiscent of the multi‐step synthesis of covalent BCPs via living chain polymerization. These findings provide a promising platform for constructing unique functional organic heterostructures for various optoelectronic and catalytic applications.

Tricomponent Supramolecular Multiblock Copolymers with Tunable Composition via Sequential Seeded Growth.

Synthesis of supramolecular block co-polymers (BCP) with small monomers and predictive sequence requires elegant molecular design and synthetic strategies. Herein we report the unparalleled synthesis of tri-component supramolecular BCPs with tunable microstructure by a kinetically controlled sequential seeded supramolecular polymerization of fluorescent π-conjugated monomers. Core-substituted naphthalene diimide (cNDI) derivatives with different core substitutions and appended with β-sheet forming peptide side chains provide perfect monomer design with spectral complementarity, pathway complexity and minimal structural mismatch to synthesize and characterize the multi-component BCPs. The distinct fluorescent nature of various cNDI monomers aids the spectroscopic probing of the seeded growth process and the microscopic visualization of resultant supramolecular BCPs using Structured Illumination Microscopy (SIM). Kinetically controlled sequential seeded supramolecular polymerization presented here is reminiscent of the multi-step synthesis of covalent BCPs via living chain polymerization. These findings provide a promising platform for constructing unique functional organic heterostructures for various optoelectronic and catalytic applications.