Tunable Internal Structure Research Articles

Multilevel Hollow-Structured Particles through Halogen-Bond Regulated Polymer Assembly under 3DConfinement.

Engineering of hollow particles with tunable internal structures often requires complicated processes and/or invasive cleavage. Halogen-bond driven 3D confined-assembly of block copolymers has shed light on the engineering of polymer organization along with the fabricating of unique nanostructures. Herein, a family of multilevel hollow-structured particles (e.g., fully porous, multi-chamber, multi-shell, and concentric multi-layer architectures) is reported via halogen-bond regulated 3Dconfined-assembly of amphiphilic polymer networks. To do so, polystyrene-b-poly(2-vinyl pyridine)-b-poly(ethylene oxide) (PS-b-P2VP-b-PEO) amphiphilic triblock copolymer is selected, where P2VP blocks act as halogen acceptor. Meanwhile, poly(3-(2,3,5,6-tetrafluoro-4-iodophenoxy) propyl acrylate) (PTFIPA) is employed as halogen donor. Halogen-bond driven donor-acceptor linking between PTFIPA and P2VP block presented in PS-b-P2VP-b-PEO, can lead to the formation of supramolecular polymeric networks, along with the increased P2VP domain and tunable hydrophobic volume. Therefore, an adjustable packing parameter (p) is thus anticipated, which can enable the morphology transformation sequence until an equilibrium state is reached. Moreover, computer simulations are further utilized as the tool to interpret such morphologies transition and identify the precise distribution of each component. Benefiting from the tunable hollow structure and a substantial surface for transporting purpose, these structurally novel particles open perspectives toward promising applications including encapsulation, nanoreactor, and catalyst support.

Tunable internal structure carbon sphere synthesis driven by water-solubility and its application in gas separation.

A method for synthesizing carbon spheres with a tunable particle size and internal structure from polyfurfuryl alcohol (PFA) was developed. By tuning the concentration of a structure directing agent (polypropylene glycol, PPG), we found a mechanism to tune the inner architecture of carbon spheres driven by water-solubility. A mixture of PFA and PPG transferred from the "water-in-oil" phase to an "oil-in-water" phase with an increasing content of PPG because of a difference in water-solubility between furfuryl alcohol (FA), PFA, and PPG. As a result, the internal morphology of the carbon sphere evolved from a "cheese-like" to a "pomegranate-like" structure, which was accompanied by an increasing specific surface area and pore volume. Furthermore, the separation of C2H2 and C2H3Cl was tested on the 25%-FACS (furfuryl alcohol-based carbon sphere) sample under different activation treatments with CO2 or CO2-NH3, with the coexisting "cheese-like" and "pomegranate-like" inner structures, owing to its moderate pore volume and mechanical strength. The maximum adsorption capacity of C2H3Cl reached 0.77 mmol g-1, while C2H2 was adsorbed in significantly lower quantities. It is believed that the high polarizability and high dipole moment of the C2H3Cl molecule primarily contribute to the excellent performance of C2H2 and C2H3Cl separation, and the introduction of polar N-containing groups on the carbon skeleton further promotes C2H3Cl adsorption.

Interfacial Supra-Assembly of Copolymer Nanoparticles Enables the Formation of Nanocomposite Crystals with a Tunable Internal Structure.

It is highly desirable but technically challenging to precisely control the spatial composition and internal structure of crystalline nanocomposite materials, especially in a one-pot synthetic route. Herein, we demonstrate a versatile pathway to tune the spatial distribution of guest species within a host inorganic crystal via an incorporation strategy. Specifically, well-defined block copolymer nanoparticles, poly(methacrylic acid)x-block-poly(styrene-alt-N-phenylmaleimide)y [PMAAx-P(St-alt-NMI)y], are synthesized by polymerization-induced self-assembly. Such anionic nanoparticles can supra-assemble onto the surface of larger cationic nanoparticles via an electrostatic interaction, forming colloidal nanocomposite particles (CNPs). Remarkably, such CNPs can be incorporated into calcite single crystals in a spatially controlled manner: the depth of CNPs incorporation into calcite is tunable. Systematic investigation indicates that this interesting phenomenon is governed by the colloidal stability of CNPs, which in turn is dictated by the PMAAx-P(St-alt-NMI)y adsorption density and calcium ion concentration. This study opens up a general and efficient route for the preparation of a wide range of crystalline nanocomposite materials with a controlled internal composition and structure.

The application of covalent organic frameworks in Lithium-Sulfur batteries: A mini review for current research progress.

Recently, how to enhance the energy density of rechargeable batteries dramatically is becoming a driving force in the field of energy storage research. Among the current energy storage technologies, the lithium-sulfur (Li-S) batteries are one of the most promising candidates for achieving high-capacity and commercial batteries. The theoretical energy density of Li-S batteries reaches to 2,600Wh kg-1 with the theoretical capacity of 1,675mAh g-1. Therefore, Li-S batteries are considered as the great potential for developing future energy storage technology. However, some of problems such as Li dendrites growth, the shuttle effect of sulfides and the electronic insulation feature of sulfur, have brought obstacles to the development of Li-S batteries. The covalent organic frameworks (COFs) are a series of porous materials with different topological structures, which show the versatile characteristics of high specific surface area, permanent pores, ordered porous channels and tunable internal structure. Potentially, their ordered channels and extended conjugated frameworks could facilitate rapid Li-ion diffusion and electron transport for the remarkable rate capability. On the basis of these merits, the COFs become the potential electrode materials to solve the above serious problems of Li-S batteries. In this mini review, we summarize the research progress of COFs utilized as electrode materials in the Li-S batteries, including the cathode, separator and anode materials. Accordingly, the outlook of COFs as electrodes for future development in Li-S batteries is also given.

Nanoengineered metal-organic framework for adsorptive and photocatalytic mitigation of pharmaceuticals and pesticide from wastewater

Rapidly expanding water pollution has transformed into significant dangers around the world. In recent years, the pharmaceutical and agriculture field attained enormous progress to meet the necessities of health and life; however, discharge of trace amounts of pharmaceuticals and pesticides into water significantly have a negative influence on human health and the environment. Contamination with these pollutants also constitutes a great threat to the aquatic ecosystem. To deal with the harmful impacts of such pollutants, their expulsion has attracted researchers’ interest a lot, and it became essential to figure out techniques suitable for the removal of these pollutants. Thus, many researchers have devoted their efforts to improving the existing technology or providing an alternative strategy to solve this environmental problem. One of the attractive materials for this purpose is metal-organic frameworks (MOFs) due to their superior high surface area, high porosity, and the tunable features of their structures and function. Among various techniques of wastewater treatment, such as biological treatment, advanced oxidation process and membrane technologies, etc., metal-organic frameworks (MOFs) materials are tailorable porous architectures and are viably used as adsorbents or photocatalysts for wastewater treatment due to their porosity, tunable internal structure, and large surface area. MOFs are synthesized by various methods such as solvo/hydrothermal, sonochemical, microwave and mechanochemical methods. Most common method used for the synthesis of MOFs is solvothermal/hydrothermal methods. Herein, this review aims at providing a comprehensive overview of the latest advances in MOFs and their derivatives, focusing on the following aspects: synthesis and applications. This review comprehensively highlights the application of MOFs and nano-MOFs to remove pharmaceuticals and pesticides from wastewater. For the past years, transition metal-based MOFs have been concentrated as photocatalyst/adsorbents in treating contaminated water. However, work on main group metal-based MOFs is not so abundant. Hence, the foremost objective of this review is to present the latest material and references concerning main group element-based MOFs and nanoscale materials derived from them towards wastewater treatment. It summarizes the possible research challenges and directions for MOFs and their derivatives as catalysts applied to wastewater treatment in the future. With the context of recent pioneering studies on main group elements-based MOFs and their derivatives; we hope to stimulate some possibilities for further development, challenges and future perspectives in this field have been highlighted.

Hyperuniform Active Chiral Fluids with Tunable Internal Structure.

Large density fluctuations observed in active systems and hyperuniformity are two seemingly incompatible phenomena. However, the formation of hyperuniform states has been recently predicted in nonequilibrium fluids formed by chiral particles performing circular motion with the same handedness. Here we report evidence of hyperuniformity realized in a chiral active fluid comprised of pear-shaped Quincke rollers of arbitrary handedness. We show that hyperuniformity and large density fluctuations, triggered by dynamic clustering, coexist in this system at different length scales. The system loses its hyperuniformity as the curvature of particles' motion increases, transforming them into localized spinners. Our results experimentally demonstrate a novel hyperuniform active fluid and provide new insights into an interplay between chirality, activity, and hyperuniformity.

Preparation of cellulose beads with high homogeneity, low crystallinity, and tunable internal structure

Preparation of cellulose beads with high homogeneity, low crystallinity, and tunable internal structure

Solvent-Free Fabrication of Biphasic Lipid-Based Microparticles with Tunable Structure

Lipid-based biphasic microparticles are generally produced by long and complex techniques based on double emulsions. In this study, spray congealing was used as a solvent-free fabrication method with improved processability to transform water-in-oil non-aqueous emulsions into spherical solid lipid-based particles with a biphasic structure (b-MPs). Emulsions were prepared by melt emulsification using different compositions of lipids (Dynasan®118 and Compritol®888 ATO), surfactants (Cetylstearyl alcohol and Span®60) and hydrophilic carriers (PEGs, Gelucire®48/16 and Poloxamer 188). First, pseudo-ternary phase diagrams were constructed to identify the area corresponding to each emulsion type (coarse emulsion or microemulsion). The hydrophobicity of the lipid mostly affected the interfacial tension, and thus the microstructure of the emulsion. Emulsions were then processed by spray congealing and the obtained b-MPs were characterized in terms of thermal and chemical properties (by DSC and FT-IR), external and internal morphology (by SEM, CLSM and Raman mapping). Solid free-flowing spherical particles (main size range 200–355 µm) with different architectures were successfully produced: microemulsions led to the formation of particles with a homogeneous internal structure, while coarse emulsions generated “multicores-shell” particles consisting of variable size hydrophilic cores evenly distributed within the crystalline lipid phase. Depending on their composition and structure, b-MPs could achieve various release profiles, representing a more versatile system than microparticles based on a single lipid phase. The formulation and technological strategy proposed, provides a feasible and cost-effective way of fabricating b-MPs with tunable internal structure and release behavior.

Hybrid metal organic frameworks as an Exotic material for the photocatalytic degradation of pollutants present in wastewater: A review

In this world, water is considered as the Elixir for all living creatures. Human life rolls with water, and every activity depends upon water. Worldwide water resources are being contaminated due to the elevation in the population count, industrialization and urbanization. Ejection of chemicals by industries and domestic sewages remains the major reason in the destruction of natural water resources. Contaminated water with harmful microbes, chemical dyes, pesticides, and carcinogens are the root cause of many diseases and deaths of living species. In this scenario, researchers engaged in producing ultra components to remove the contaminants. Metal organic frameworks (MOF) are the desired combination of organic and inorganic materials to achieve the required target. MOFs possess unique characteristics like tunable internal structure, porosity, crystallinity and high surface area which enable them for energy and environmental application. For the past years, MOFs are concentrated more as a photocatalyst in the treatment of polluted water. These research studies discuss the improvement of photocatalytic performance of MOF by the incorporation of metals, metal coupled with nanoparticles like polymers, graphene, etc., into it to achieve the enhanced photocatalytic activity by scavenging entire chemicals and harmful microbes to retain the quality of water. The target of this review article is to focus on the state of the art research work on MOFs in photocatalytic water treatment technique.

Porous cage-derived nanomaterial inks for direct and internal three-dimensional printing

The convergence of 3D printing techniques and nanomaterials is generating a compelling opportunity space to create advanced materials with multiscale structural control and hierarchical functionalities. While most nanoparticles consist of a dense material, less attention has been payed to 3D printing of nanoparticles with intrinsic porosity. Here, we combine ultrasmall (about 10 nm) silica nanocages with digital light processing technique for the direct 3D printing of hierarchically porous parts with arbitrary shapes, as well as tunable internal structures and high surface area. Thanks to the versatile and orthogonal cage surface modifications, we show how this approach can be applied for the implementation and positioning of functionalities throughout 3D printed objects. Furthermore, taking advantage of the internal porosity of the printed parts, an internal printing approach is proposed for the localized deposition of a guest material within a host matrix, enabling complex 3D material designs.

Impact of Reactive Amphiphilic Copolymers on Mechanical Properties and Cell Responses of Fibrin‐Based Hydrogels

AbstractMechanical properties of hydrogels can be modified by the variation of structure and concentration of reactive building blocks. One promising biological source for the synthesis of biocompatible hydrogels is fibrinogen. Fibrinogen is a glycoprotein in blood, which can be transformed enzymatically to fibrin playing an important role in wound healing and clot formation. In the present work, it is demonstrated that hybrid hydrogels with their improved mechanical properties, tunable internal structure, and enhanced resistance to degradation can be synthesized by a combination of fibrinogen and reactive amphiphilic copolymers. Water‐soluble amphiphilic copolymers with tunable molecular weight and controlled amounts of reactive epoxy side groups are used as reactive crosslinkers to reinforce fibrin hydrogels. In the present work, copolymers that can influence the mechanical properties of fibrin‐based hydrogels are used. The reactive copolymers increase the storage modulus of the hydrogels from 600 Pa to 30 kPa. The thickness of fibrin fibers is regulated by the copolymer concentration. It could be demonstrated that the fibrin‐based hydrogels are biocompatible and support cell proliferation. Their degradation rate is considerably slower than that of native fibrin gels. In conclusion, fibrin‐based hydrogels with tunable elasticity and fiber thickness useful to direct cell responses like proliferation and differentiation are produced.

Three-dimensional nanocomposite of graphene/MWCNT hydrogel grafted with Ni–Co hydroxide nanorods as high-performance electrode for asymmetric supercapacitor

Graphene hydrogels with a three-dimensional (3D) structure have attracted attention as electrode materials for energy storage devices due to their macroscopic architecture and freestanding characteristics. In this work, 3D graphene/MWCNT hydrogel (GCH) with a tunable internal structure was self-assembled through chemical reduction and used as an electrode material for supercapacitor. The added MWCNTs prevent aggregation of graphene sheets and increase available active sites. Furthermore, the high conductivity and strength of MWCNTs greatly tuned the structural and physical properties of the hydrogel. Nickel-cobalt hydroxide nanorods were further grafted on GCH scaffold by a hydrothermal method. Due to its good electrolyte accessibility and fast charge transfer, the resulting GCH-NC shows high specific capacity and outstanding rate performance when it is used as electrode material for supercapacitor. For practical applications, asymmetric supercapacitor is fabricated using GCH and GCH-NC as negative and positive electrode materials, respectively. The fabricated asymmetric supercapacitor exhibits excellent performance with an energy density of 0.36 mWh/cm2 and a high power density of 22.6 mW/cm2 (loading mass: 10.6 mg/cm2). Also, this device possesses outstanding cycle stability with capacity retention of 92% after 25,000 cycles at a current density 10 A/cm2. Therefore, the GCH-NC is expected to be a promising electrode material for high-performance supercapacitor.

Nanofilamentous Virus-Based Dynamic Hydrogels with Tunable Internal Structures, Injectability, Self-Healing, and Sugar Responsiveness at Physiological pH.

With expanding applications of hydrogels in diverse fields ranging from biomaterials to sensors, actuators, and soft robotics, there is an urgent need to endow one single gel with multiple physicochemical properties, such as stimuli-responsiveness, injectability, self-healing, and tunable internal structures. However, it is challenging to simultaneously incorporate these highly sought-after properties into one single gel. Herein, a conceptual hydrogel system with all of these properties is presented via combining bioconjugate chemistry, filamentous viruses, and dynamic covalent bonds. Nanofilamentous bioconjugates with diol affinity were prepared by coupling a tailor-synthesized low-p Ka phenylboronic acid (PBA) derivative to a well-defined green nanofiber the M13 virus with a high aspect ratio (PBA-M13). Dynamic hydrogels with tunable mechanical strength were prepared by using multiple diol-containing agents such as poly(vinyl alcohol) to cross-link such PBA-M13 via the classic boronic-diol dynamic bonds. The as-prepared hydrogels exhibit excellent injectability and self-healing behaviors as well as easy chemical accessibility of the PBA moieties on the virus backbone inside the gel matrix. Ordered internal structures were imparted into virus-based hydrogels by simple shear-induced alignment of the virus nanofibers. Furthermore, unique hydrogels with chiral internal structures were fabricated through in situ gelation induced by diffusion of diol-containing molecules to fix the chiral liquid crystal phase of the PBA-M13 virus. Sugar responsiveness of this gel leads to a glucose-regulated release behavior of payloads such as insulin. All of these properties have been implemented at physiological pH, which will facilitate future applications of these hydrogels as biomaterials.

Temperature-Dependent Structure of Two-Dimensional Hybrid NaCl-PTCDI Nanoarchitectures on Au(111)

PTCDI molecules and NaCl self-assemble on the Au(111) surface to form two-dimensional porous hybrid nanoarchitectures. Scanning tunneling microscopy (STM) reveals that temperature can drastically influence the structure of these nanoarchitectures. A PTCDI-NaCl flower structure is created after codeposition onto a surface at 20 °C. The molecules and the ionic compound form a mesh nanoarchitecture after annealing at 100 °C, a ladder nanoarchitecture after annealing at 140 °C, and a chain nanoarchitecture after annealing at 150 °C. Close-packed PTCDI islands surrounded by single PTCDI-NaCl chains are observed after annealing at 160 °C. STM shows that NaCl interacts selectively and locally with molecular N-H groups. This organic–ionic interaction is highly directional. A temperature increase appears to first favor the ordering of PTCDI and NaCl compound and then to favor the formation of higher density structures. At high temperature, the ionic compound desorbs from the surface. This combination of organic and ionic compounds is a promising system to engineer novel 2D materials with a tunable internal structure.

An alternative approach to the phase change of proteins in an aqueous mixture with ethanol

Microdroplets have a wide extent of applications due to the related advantages, such as high throughput, compartmentalization with a deep control of the single volume. Herein, a microdroplet-based device for protein phase transition was displayed. In doing so, biphasic droplets with tunable internal structures and phase with near-equilibrium drop-in-drop morphology were created. The protein phase was controlled by modulating the composition, and the flow velocities. The microfluidic device allowed investigating the morphology of the protein and the phase transition from gelation to crystallization, via the formation of the magma-unstable phase. The creation of droplets with tunable spatial heterogeneity could be exploited in biochemical investigations.

Fabrication of Free-floating Nanohybrid Microparticles with ZnO Nanowire Surfaces

A photopolymerization technique with UV-photocurable materials using optofluidic maskless lithography (OFML) provides great flexibility in generating microstructure in microfluidic channels, such as continuous flow lithography and optofluidic lithography. These techniques enable the production of various microstructures with freeform shapes and high throughput because of its continuous synthetic process. Photocurable materials can generate polymeric microstructures with tunable internal structures, shapes, and surface properties. They have potential applications in particle-based technologies such as encoded chemical-laden microparticles, QR-encoded polymeric microparticles, and functional microparticles with complex nanostructured compartments. Recently, polymeric microstructures have been widely used in cell biology, including in scaffolding materials, tissue regeneration, and cellular studies, they can be used as three-dimensional (3D) tissue-like structures assembled by biological structures. Most researches on nanowire technology for cellular physiology have been based on nanowires on a two-dimensional planar substrate. For more flexible and scalable expansion of biomimetic surface for cellular study, we have focused on three-dimensional tissue-like structures assembled with microscale building blocks. In bottom-up approach for forming biomimetic extracellular matrix including nanowires, the unit of the structure is required to have nanowires on its surface. We present a novel nanohybrid microparticle inspired by a natural extracellular matrix composed of an interlocking mesh of fibrous proteins and carbohydrate polymers that can be used as a biomimetic material. The novel polymeric microparticle is a 3D shape with spiked ZnO nanowires on its surface. ZnO nanowires have been used for biochemical sensing devices that detect proteins, viruses and pH levels. Moreover, ZnO nanowire structures are an effective extracellular matrix to guide cell migration or control cell differentiation. Herein, we introduce fabrication of free-floating nanohybrid microparticles with a ZnO nanowire surface. The fabrication process of nanohybrid microparticles is composed of two main steps. First, freeform shapes of microparticles are generated by photopolymerization using an OFML system. After preparation of the microparticles, silica layers are deposited to provide texture seeds for the ZnO nanowires. Then, the ZnO nanowires are grown on the surface of microparticles via a hydrothermal reaction process. We can control the density of the ZnO nanowires on the microparticle during seeding processes. In order to produce nanohybrid microparticles, we prepare an UV-photocurable resin, ethoxylated trimethylolpropane triacrylate (ETPTA, Sigma-Aldrich, St. Louis, MO) and UV photoinitiator (2,2-dimethoxy-2-phenylacetophenone, SigmaAldrich, St. Louis, MO) for synthesis of polymeric microparticles. For silica layer deposition, we also prepare 98% tetraethyl orthosilicate (TEOS, Sigma-Aldrich, St. Louis, MO) and a mixed solution that consists of deionized water, 99% ethanol (Daejung, Korea), and 25-28% ammonium hydroxide (Daejung, Korea). After synthesizing polymeric microparticles by photopolymerization of the mixture consisting of ETPTA and 10 wt % photoinitiator using maskless lithography, polymeric particles are incubated in solution for the silica-coating reaction by periodically injecting TEOS into the mixed solution using the Stober method. The surface of elastic polymer microparticles is coated with an inelastic silica film forming a core–shell structure. Texture seeds are used for ZnO nanowire synthesis on the surface of the microparticles. A solution that contains 0.005

Piezoelectric control of the mobility of a domain wall driven by adiabatic and non-adiabatic torques

The rich internal degrees of freedom of magnetic domain walls make them an attractive complement to electron charge for exploring new concepts of storage, transport and processing of information. Here we use the tunable internal structure of a domain wall in a perpendicularly magnetized GaMnAsP/GaAs ferromagnetic semiconductor and demonstrate devices in which piezoelectrically controlled magnetic anisotropy yields up to 500% mobility variations for an electrical-current-driven domain wall. We observe current-induced domain wall motion over a wide range of current-pulse amplitudes and report a direct observation and the piezoelectric control of the Walker breakdown separating two regimes with different mobilities. Our work demonstrates that in spin-orbit-coupled ferromagnets with weak extrinsic domain wall pinning, the piezoelectric control allows one to experimentally assess the upper and lower boundaries of the characteristic ratio of adiabatic and non-adiabatic spin-transfer torques in the current-driven domain wall motion.

Tunable spatial heterogeneity in structure and composition within aqueous microfluidic droplets

In this paper, we demonstrate biphasic microfluidic droplets with broadly tunable internal structures, from simple near-equilibrium drop-in-drop morphologies to complex yet uniform non-equilibrium steady-state structures. The droplets contain an aqueous mixture of poly(ethylene glycol) (PEG) and dextran and are dispensed into an immiscible oil in a microfluidic T-junction device. Above a certain well-defined threshold droplet speed, the inner dextran-rich phase is "stirred" within the outer PEG-rich phase. The stirred polymer mixture is observed to exhibit a near continuum of speed and composition-dependent phase morphologies. There is increasing interest in the use of such aqueous two-phase systems in microfluidic devices for biomolecular applications in a variety of contexts. Our work presents a method to go beyond equilibrium phase morphologies in generating microfluidic "multiple" emulsions and at the same time raises the possibility of biochemical experimentation in benign yet complex biomimetic milieus.

Mesoporous Block Copolymer Nanoparticles with Tailored Structures by Hydrogen‐Bonding‐Assisted Self‐Assembly

A simple, yet robust route to prepare polymer nanoparticles with tunable internal structures through supramolecular assembly within emulsion droplets is presented. Nanoparticles with various internal morphologies, including dispersed spheres, dispersed spirals, stacked toroids, and concentric lamellae, are obtained due to the 3D confinement and variation of hydrogen-bonding agent. This method also allows us to form mesoporous particles through further disassembly of the supramoleclar assemblies by rupturing the hydrogen bonding.

Nanoparticles with Tunable Internal Structure from Triblock Copolymers of PAA-b-PMA-b-PS

Polymer nanoparticles containing their own inherent nanostructure (lamellar, bicontinuous-like, or porous) were formed via the self-assembly of a triblock copolymer complexed with a multiamine counterion in mixed solvents. The internal nanostructure is due to local phase separation of the block copolymers and can be tuned by varying the solvent composition, the relative block composition, and the valency of the organic counterion.