Toward High-Efficient Chiral Separation Using Hierarchically Porous HROP@Silica-Gel-Sheet Composite

Separating racemates is still a great challenge for their similarity in chemical structures and physicochemical properties. Despite exhibiting a significant potential in the adsorption separation due to their intrinsic characteristics, hierarchically porous materials utilized in enantioseparation have rarely been reported to date. Furthermore, the molding of such materials together with their hybrid organic-inorganic monoliths is generally required to meet various prerequisites in diverse large-scale industrial applications, but without sacrificing their inherently hierarchical architectures. In this work, a three-dimensional hierarchically porous organic-inorganic composite was simply and feasibly prepared via integrating the micro/meso-porous hyper-cross-linked resin organic polymer (HROP) with macroporous silica gel sheet (SGS), followed by a chiral selector postmodification, named as HROP@SGS. Racemic 1-phenylethanol, ibuprofen, and naproxen could be separated only using such a piece of HROP@SGS as the filler with a solid phase extraction technique. Herein, HROP@SGS exhibited extraordinary chiral resolution performances and succeeded in achieving a complete chiral resolution. Our findings suggest that this simple strategy proposed by us, that is, combining the chiral micro/mesoporous organic materials with macroporous inorganic substrates, can be employed to prepare an unprecedented enantioseparation material, which has a promising potential in large-scale industrial applications, such as fixed-bed and membrane separation.

Polymer-guided assembly of inorganic nanoparticles

The self-assembly of inorganic nanoparticles is of great importance in realizing their enormous potentials for broad applications due to the advanced collective properties of nanoparticle ensembles. Various molecular ligands (e.g., small molecules, DNAs, proteins, and polymers) have been used to assist the organization of inorganic nanoparticles into functional structures at different hierarchical levels. Among others, polymers are particularly attractive for use in nanoparticle assembly, because of the complex architectures and rich functionalities of assembled structures enabled by polymers. Polymer-guided assembly of nanoparticles has emerged as a powerful route to fabricate functional materials with desired mechanical, optical, electronic or magnetic properties for a broad range of applications such as sensing, nanomedicine, catalysis, energy storage/conversion, data storage, electronics and photonics. In this review article, we summarize recent advances in the polymer-guided self-assembly of inorganic nanoparticles in both bulk thin films and solution, with an emphasis on the role of polymers in the assembly process and functions of resulting nanostructures. Precise control over the location/arrangement, interparticle interaction, and packing of inorganic nanoparticles at various scales are highlighted.

Multi-drug hybrid delivery systems with distinct release profiles based on gelatin/collagen containing vesicles derived from block copolymers

Hybrid delivery systems can release multiple drugs with different profiles and have several applications, including skin dressing. In this work, the co-solvent technique was used for the preparation of nanometric vesicles based on poly(styrene-b-ethylene oxide) block copolymer (BCPVs) containing adapalene (AD). The BCPVs were incorporated into collagen and gelatin matrices together with free AD and silver sulfadiazine (SSD). The AD content of BCPVs and their release capacity were analyzed by using ultraviolet-visible spectroscopy (UV-Vis). The gelatin and collagen matrices were evaluated for their ability to release AD and SSD through an in vitro release study. The obtained results confirmed that the production of empty and AD-loaded BCPVs was viable. The degree of AD encapsulation in BCPVs was 9.0% and the in vitro test revealed a constant, slow, and prolonged release of AD content from AD-loaded BCPVs. The combination of free and encapsulated multiple drugs in hybrid delivery systems based on gelatin and collagen matrices was shown to act as a skin dressing that combined the progressive release of large amounts of drugs within the first hours of use (to restrict infection) with a more prolonged and slow release of AD to enhance skin healing.

Thiol-ene polymerization for hierarchically porous hybrid materials by adding degradable polycaprolactone for adsorption of bisphenol A

Hierarchically porous materials with multiple pore structures have the potential application in catalysis, separation or bioengineering. A concept was introduced to design and fabricate hierarchically porous hybrid materials (HPHMs) simultaneously containing mesopores and macropores. The proof-of-concept design was demonstrated by fabrication of several kinds of hybrid materials by adding degradable polycaprolactone (PCL) additive, which was simple and easy-operating. The specific surface areas of HPHMs prepared with polyhedral oligomeric vinylsilsesquioxanes (vinylPOSS) and 1,4-dithiothreitol (DTT) could reach 727 m²/g by adding 25% PCL additive, while the HPHMs were imperforate prior to degradation of PCL. The characterization further indicated that the macropores could be controlled by the amount of PCL additive. Moreover, the porous properties of HPHMs were influenced by the molecular weight of PCL. Other dithiols compounds were also successful in preparing HPHMs with high specific surface areas over 400 m²/g. Due to hydrophobic interaction and hydrogen bond interaction, the HPHM exhibited good adsorption ability for bisphenol A (BPA) in aqueous solution. Adsorption equilibrium could be achieved within 30 min, and the adsorption capacity was up to 157.4 mg/g. Meanwhile, the removal efficiency was found to be 95.37% for BPA.

Ordered Porous Poly(ionic liquid) Crystallines: Spacing Confined Ionic Surface Enhancing Selective CO2 Capture and Fixation

Porous poly(ionic liquid)s (PPILs) combine the features of porous materials, polymers, and ionic liquids (ILs) or their derivatives, but they are normally of amorphous structure with disordered pores. Here, we report the facile synthesis of ordered porous poly(ionic liquid) crystallines (OPICs, specialized as a kind of PPIL analogues) with diverse and adjustable framework IL moieties through the Schiff base condensation of IL-derived ionic salts and neutral monomers. Ternary monomer mixtures are employed to artistically control the chemical composition and pore configurations. Compact atomic packing was achieved to give spacing confined ionic surface with strong CO₂ affinity. Through monomer control, OPICs exhibit high CO₂ uptakes with excellent CO₂/N₂(CH₄) selectivities and efficiently implement CO₂ fixation through catalyzing epoxides cycloaddition under down to ambient conditions.

Block copolymer derived uniform mesopores enable ultrafast electron and ion transport at high mass loadings

High mass loading and fast charge transport are two crucial but often mutually exclusive characteristics of pseudocapacitors. On conventional carbon supports, high mass loadings inevitably lead to sluggish electron conduction and ion diffusion due to thick pseudocapacitive layers and clogged pores. Here we present a design principle of carbon supports, utilizing self-assembly and microphase-separation of block copolymers. We synthesize porous carbon fibers (PCFs) with uniform mesopores of 11.7 nm, which are partially filled with MnO2 of <2 nm in thickness. The uniform mesopores and ultrathin MnO2 enable fast electron/ion transport comparable to electrical-double-layer-capacitive carbons. At mass loadings approaching 7 mg cm-2, the gravimetric and areal capacitances of MnO2 (~50% of total mass) reach 1148 F g-1 and 3141 mF cm-2, respectively. Our MnO2-coated PCFs outperform other MnO2-based electrodes at similar loadings, highlighting the great promise of block copolymers for designing PCF supports for electrochemical applications.

Monitoring morphology evolution within block copolymer microparticles during dispersion polymerisation in supercritical carbon dioxide: a high pressure SAXS study

Monitoring morphology development and evolution within block copolymer microparticles dispersed in supercritical CO₂ using in situ SAXS.

Polymer cubosomes of block copolymers having cross-linkable soft hydrophobic blocks

Inverse bicontinuous cubic mesophases of block copolymers are an emerging class of mesoporous structures consisting of block copolymer bilayers, in which well-defined reticulated pore networks are intertwined in a long-range crystalline order.

Preparation of Highly Porous Polymer Membranes with Hierarchical Porous Structures via Spinodal Decomposition of Mixed Solvents with UCST Phase Behavior

The predominant method to prepare polymer membranes is based on phase inversion. However, this method always leads to a dense skin with low porosity when normal polymers are used. Using the self-assembly of certain block copolymers, it is possible to prepare uniform pores with high porosity, but the prices of these polymers are too high to be afforded in practical applications. Here, we report a novel strategy to prepare highly porous and asymmetric polymer membranes using the widely used poly(vinylidene fluoride) (PVDF) as a prototype. The method combines spinodal decomposition with phase inversion utilizing mixed solvents that have the unique upper critical solution temperature phase behavior. The spinodal decomposition generates a thin surface layer containing a high density of relatively uniform pores in the mesoporous range, and the phase inversion generates a thick bulk layer composed of macrovoids; the two types of structures are interconnected, yielding a highly permeable, selective, and mechanically strong porous membrane. The membranes show an order of magnitude higher water permeance than commercial membranes and efficient molecular sieving of macromolecules. Notably, our strategy provides a general toolbox to prepare highly porous membranes from normal polymers. By blending PVDF with cellulose acetate (CA), a highly porous PVDF/CA membrane was prepared and showed similarly high separation performance, but the higher hydrophilicity of CA improved the membrane flux in the presence of proteins.

Synthesis and Formation Mechanism of All-Organic Block Copolymer-Directed Templating of Laser-Induced Crystalline Silicon Nanostructures

This report describes the generation of three-dimensional (3D) crystalline silicon continuous network nanostructures by coupling all-organic block copolymer self-assembly-directed resin templates with low-temperature silicon chemical vapor deposition and pulsed excimer laser annealing. Organic 3D mesoporous continuous-network resin templates were synthesized from the all-organic self-assembly of an ABC triblock terpolymer and resorcinol-formaldehyde resols. Nanosecond pulsed excimer laser irradiation induced the transient melt transformation of amorphous silicon precursors backfilled in the organic template into complementary 3D mesoporous crystalline silicon nanostructures with high pattern fidelity. Mechanistic studies on laser-induced crystalline silicon nanostructure formation revealed that the resin template was carbonized during transient laser-induced heating on the milli- to nanosecond timescales, thereby imparting enhanced thermal and structural stability to support the silicon melt-crystallization process at temperatures above 1250 °C. Photoablation of the resin material under pulsed excimer laser irradiation was mitigated by depositing an amorphous silicon overlayer on the resin template. This approach represents a potential pathway from organic block copolymer self-assembly to alternative functional hard materials with well-ordered 3D morphologies for potential hybrid photovoltaics, photonic, and energy storage applications.

Assembly of colloidal particles in solution

Advances in both top-down and bottom-up syntheses of a wide variety of complex colloidal building blocks and also in methods of controlling their assembly in solution have led to new and interesting forms of highly controlled soft matter. In particular, top-down lithographic methods of producing monodisperse colloids now provide precise human-designed control over their sub-particle features, opening up a wide range of new possibilities for assembly structures that had been previously limited by the range of shapes available through bottom-up methods. Moreover, an increasing level of control over anisotropic interactions between these colloidal building blocks, which can be tailored through local geometries of sub-particle features as well as site-specific surface modifications, is giving rise to new demonstrations of massively parallel off-chip self-assembly of specific target structures with low defect rates. In particular, new experimental realizations of hierarchical self-assembly and control over the chiral purity of resulting assembly structures have been achieved. Increasingly, shape-dependent, shape-complementary, and roughness-controlled depletion attractions between non-spherical colloids are being used in novel ways to create assemblies that go far beyond early examples, such as fractal clusters formed by diffusion-limited and reaction-limited aggregation of spheres. As self-assembly methods have progressed, a wide variety of advanced directed assembly methods have also been developed; approaches based on microfluidic control and applying structured electromagnetic fields are particularly promising.

Sol-gel preparation of titanium (IV)-immobilized hierarchically porous organosilica hybrid monoliths

Hierarchically porous monoliths as a key feature of biological materials have been applied in enrichment and separation. In this work, a metal immobilized hierarchically porous organosilica hybrid monolith was synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and diethoxyphosphorylethyl-triethoxysilane (DPTS) under alkaline environment. Phosphonate ester groups were firstly introduced by the employment of DPTS as functional monomer, and then acidified to phosphonic acids. The surface area of optimal monolith could reach to 1170 m²/g, which simultaneously contained micropores and mesopores (4 nm) obtained from nitrogen sorption measurement. Meanwhile, mercury intrusion porosimetry (MIP) further demonstrated that macropores (1-3 μm) existed in monoliths. Followed by chelating with titanium ion (Ti⁴⁺), the hierarchically porous organosilica hybrid monoliths could be applied as IMAC materials. This synthesized process was easy-operating and time-saving, and avoided the tedious and complex process of traditional Ti⁴⁺-IMAC materials. Furthermore, the Ti⁴⁺-IMAC monoliths exhibited high adsorption capacity for pyridoxal 5'-phosphate (82.6 mg/g). The 3282 unique phosphopeptides could be identified from 100 μg of HeLa digests after enrichment with the monolith, exhibiting excellent enrichment performance of low-abundance phosphopeptides.

Construction of hierarchically porous monoliths from covalent organic frameworks (COFs) and their application for bisphenol A removal

Subject to synthetic conditions, covalent organic frameworks (COFs) are usually in powder form. Herein, taking an azine-linked COF as an example, detailed characterizations indicated that accessible aldehyde groups and hydrazine groups (CNNH₂, 88 μmol g^-1) concurrently existed on its surface. Intrigued by such feature, we have developed an approach based on ring-opening polymerization to shape COF powder into monoliths. The crystallinity and micropore of COF in monoliths were well remained, meanwhile, the ring-opening polymerization remarkably generated macropores ranging from 0.43 to 3.51 μm, indicating a hierarchically porous structure. The BET surface area of resultant monoliths with different COF mass fractions of 16%, 28% and 43% ranged from 105 to 281 m² g^-1. Due to the π-π interaction and hydrogen bond interaction, COF-based monoliths exhibited strong retention and rapid adsorption for bisphenol A (BPA) in aqueous medium. When 29 mL BPA solution (22.8 mg L^-1) passed through COF-based monolith (28%), the adsorption capacity was up to 61.3 mg g^-1. Furthermore, the COF-based monolith demonstrated excellent cycle use for catalyzing Suzuki-Miyaura coupling reaction after being coordinated with palladium acetate.

Substrate Patterning Using Regular Macroporous Block Copolymer Monoliths as Sacrificial Templates and as Capillary Microstamps

Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) monoliths containing regular arrays of macropores (diameter ≈1.1 µm, depth ≈0.7 µm) at their surfaces are used to pattern substrates by patterning modes going beyond the functionality of classical solid elastomer stamps. In a first exemplary application, the macroporous PS-b-P2VP monoliths are employed as sacrificial templates for the deposition of NaCl nanocrystals and topographically patterned iridium films. One NaCl nanocrystal per macropore is formed by evaporation of NaCl solutions filling the macropores followed by iridium coating. Thermal PS-b-P2VP decomposition yields topographically patterned iridium films consisting of ordered arrays of hexagonal cells, each of which contains one NaCl nanocrystal. For the second exemplary application, spongy-continuous mesopore systems are generated in the macroporous PS-b-P2VP monoliths by selective-swelling induced pore generation. Infiltrating the spongy-continuous mesopore systems with ink allows capillary microstamping of continuous ink films with holes at the positions of the macropores onto glass slides compatible with advanced light microscopy. Capillary microstamping can be performed multiple times under ambient conditions without reinking and without quality deterioration of the stamped patterns. The macroporous PS-b-P2VP monoliths are prepared by double replication of primary macroporous silicon molds via secondary polydimethylsiloxane molds.

Generalized Access to Mesoporous Inorganic Particles and Hollow Spheres from Multicomponent Polymer Blends

Mesoporous inorganic particles and hollow spheres are of increasing interest for a broad range of applications, but synthesis approaches are typically material specific, complex, or lack control over desired structures. Here it is reported how combining mesoscale block copolymer (BCP) directed inorganic materials self-assembly and macroscale spinodal decomposition can be employed in multicomponent BCP/hydrophilic inorganic precursor blends with homopolymers to prepare mesoporous inorganic particles with controlled meso- and macrostructures. The homogeneous multicomponent blend solution undergoes dual phase separation upon solvent evaporation. Microphase-separated (BCP/inorganic precursor)-domains are confined within the macrophase-separated majority homopolymer matrix, being self-organized toward particle shapes that minimize the total interfacial area/energy. The pore orientation and particle shape (solid spheres, oblate ellipsoids, hollow spheres) are tailored by changing the kind of homopolymer matrix and associated enthalpic interactions. Furthermore, the sizes of particle and hollow inner cavity are tailored by changing the relative amount of homopolymer matrix and the rates of solvent evaporation. Pyrolysis yields discrete mesoporous inorganic particles and hollow spheres. The present approach enables a high degree of control over pore structure, orientation, and size (15-44 nm), particle shape, particle size (0.6-3 µm), inner cavity size (120-700 nm), and chemical composition (e.g., aluminosilicates, carbon, and metal oxides).

Porous Polyelectrolytes: The Interplay of Charge and Pores for New Functionalities

The past decade has witnessed rapid advances in porous polyelectrolytes and there is tremendous interest in their synthesis as well as their applications in environmental, energy, biomedicine, and catalysis technologies. Research on porous polyelectrolytes is motivated by the flexible choice of functional organic groups and processing technologies as well as the synergy of the charge and pores spanning length scales from individual polyelectrolyte backbones to their nano-/micro-superstructures. This Review surveys recent progress in porous polyelectrolytes including membranes, particles, scaffolds, and high surface area powders/resins as well as their derivatives. The focus is the interplay between surface chemistry, Columbic interaction, and pore confinement that defines new chemistry and physics in such materials for applications in energy conversion, molecular separation, water purification, sensing/actuation, catalysis, tissue engineering, and nanomedicine.

Artificial 3D hierarchical and isotropic porous polymeric materials

Hierarchical porous materials that replicate complex living structures are attractive for a wide variety of applications, ranging from storage and catalysis to biological and artificial systems. However, the preparation of structures with a high level of complexity and long-range order at the mesoscale and microscale is challenging. We report a simple, nonextractive, and nonreactive method used to prepare three-dimensional porous materials that mimic biological systems such as marine skeletons and honeycombs. This method exploits the concurrent occurrence of the self-assembly of block copolymers in solution and macrophase separation by nucleation and growth. We obtained a long-range order of micrometer-sized compartments. These compartments are interconnected by ordered cylindrical nanochannels. The new approach is demonstrated using polystyrene-b-poly(t-butyl acrylate), which can be further explored for a broad range of applications, such as air purification filters for viruses and pollution particle removal or growth of bioinspired materials for bone regeneration.

An ideal enzyme immobilization carrier: a hierarchically porous cellulose monolith fabricated by phase separation method

Cellulose monolith with a hierarchically porous morphology was utilized as a novel solid support for enzyme immobilization. After a series of modifications, succinimidyl carbonate (SC)-activated cellulose monolith (SCCL monolith) was obtained and it was employed to immobilize a model enzyme (horseradish peroxidase, HRP) through covalent bonding. The HRP immobilization capacity on SCCL monolith was calculated as 21.0 mg/g. The thermal stability measurement illustrated that the immobilized HRP exhibited a largely improved thermal resistance compared to its free counterpart. The reusability of the immobilized HRP was investigated, and it could be reused at least 10 cycles without significant activity loss. Therefore, cellulose monolith is found to be an ideal solid support for enzyme immobilization.

Directed Self-Assembly of Star-Block Copolymers by Topographic Nanopatterns through Nucleation and Growth Mechanism

Exploring the ordering mechanism and dynamics of self-assembled block copolymer (BCP) thin films under confined conditions are highly essential in the application of BCP lithography. In this study, it is aimed to examine the self-assembling mechanism and kinetics of silicon-containing 3-arm star-block copolymer composed of polystyrene (PS) and poly(dimethylsiloxane) blocks as nanostructured thin films with perpendicular cylinders and controlled lateral ordering by directed self-assembly using topographically patterned substrates. The ordering process of the star-block copolymer within fabricated topographic patterns with PS-functionalized sidewall can be carried out through the type of secondary (i.e., heterogeneous) nucleation for microphase separation initiated from the edge and/or corner of the topographic patterns, and directed to grow as well-ordered hexagonally packed perpendicular cylinders. The growth rate for the confined microphase separation is highly dependent upon the dimension and also the geometric texture of the preformed pattern. Fast self-assembly for ordering of BCP thin film can be achieved by lowering the confinement dimension and also increasing the concern number of the preformed pattern, providing a new strategy for the design of BCP lithography from the integration of top-down and bottom-up approaches.

Wood Nanotechnology for Strong, Mesoporous, and Hydrophobic Biocomposites for Selective Separation of Oil/Water Mixtures

Tremendous efforts have been dedicated to developing effective and eco-friendly approaches for separation of oil-water mixtures. Challenges remain in terms of complex processing, high material cost, low efficiency, and scale-up problems. Inspired by the tubular porosity and hierarchical organization of wood, a strong, mesoporous, and hydrophobic three-dimensional wood structure is created for selective oil/water separation. A delignified wood template with hydrophilic characteristics is obtained by removal of lignin. The delignified wood template is further functionalized by a reactive epoxy-amine system. This wood/epoxy biocomposite reveals hydrophobic/oleophilic functionality and shows oil absorption as high as 15 g/g. The wood/epoxy biocomposite has a compression yield strength and modulus up to 18 and 263 MPa, respectively, at a solid volume fraction of only 12%. This is more than 20 times that of cellulose-based foams/aerogels reconstructed from cellulose nanofibrils. The favorable performance is ascribed to the natural hierarchical honeycomb structure of wood. Oil can be selectively absorbed not only from below but also from above the water surface. High oil/water absorption capacity of both types of wood structures (delignified template and polymer-modified biocomposite) allows for applications in oil/water separation.

Directed Self-Assembly of Asymmetric Block Copolymers in Thin Films Driven by Uniaxially Aligned Topographic Patterns

We present a simple, versatile approach to generate highly ordered nanostructures of block copolymers (BCPs) using rubbed surfaces. A block of poly(tetrafluoroethylene) (PTFE) was dragged across a flat substrate surface above the melting point of PTFE transferring a highly aligned PTFE topographic pattern to the substrate. Si wafer, glass, and polyimide films were used as substrates. Thin films of cylinder-forming asymmetric polystyrene-block-poly(2-vinylpyridine) copolymers (S2VPs) were solvent annealed on the surfaces having the transferred surface pattern to induce their directed self-assembly. Cylinders of P2VP oriented normal to the surface are markedly aligned along the rubbing direction and used as templates to generate extremely uniform arrays of various metallic nanoparticles of gold, silver, and platinum over a large area.

Multiscale Phase Separations for Hierarchically Ordered Macro/Mesostructured Metal Oxides

Porous architectures play an important role in various applications of inorganic materials. Several attempts to develop mesoporous materials with controlled macrostructures have been reported, but they usually require complicated multiple-step procedures, which limits their versatility and suitability for mass production. Here, a simple approach for controlling the macrostructures of mesoporous materials, without templates for the macropores, is reported. The controlled solvent evaporation induces both macrophase separation via spinodal decomposition and mesophase separation via block copolymer self-assembly, leading to the formation of hierarchically porous metal oxides with periodic macro/mesostructures. In addition, using this method, macrostructures of mesoporous metal oxides are controlled into spheres and mesoporous powders containing isolated macropores. Nanocomputed tomography, focused ion beam milling, and electron microscopy confirm well-defined macrostructures containing mesopores. Among the various porous structures, hierarchically macro/mesoporous metal oxide is employed as an anode material in lithium-ion batteries. The present approach could provide a broad and easily accessible platform for the manufacturing of mesoporous inorganic materials with different macrostructures.

Hard-template synthesis of micro-mesoporous organic frameworks with controlled hierarchicity

A hard-template synthesis strategy has been developed to prepare hierarchically porous organic frameworks. The prepared materials exhibit uniform micropores and ordered mesopores.

Self-assembly of 3D porous architectures from energetic nanoparticles for enhanced energetic performances

3D architectures with porous network of energetic molecules were designed and constructed by introduce a general approach through two-step self-assembly process.

Swelling-induced pore generation in fluorinated polynorbornene block copolymer films

Synthesis of fluorinated polynorbornene BCPs and swelling-induced pore generation of their films using fluorous solvent.

Highly porous and chemical resistive P(TFEMA–DVB) monolith with tunable morphology for rapid oil/water separation

A facile preparation for a series of porous poly(2,2,2-trifluoroethylmethacrylate–divinylbenzene) P(TFEMA–DVB) foams is discussed in this paper. The foams have adjustable morphology utilizing a suitable commercial surfactant, Hypermer B246, as stabilizer, and were compared with traditional organic surfactants or macromolecular block-polymers. Combining the porous properties and advantages of fluorine atoms, this type of fluoropolymer exhibited superb chemical stability and hydrophobicity performances with high porosity. These porous fluoro-monoliths preserved their regular porous structure without any degradation after immersion into strong acidic or basic solution for three days, hence demonstrating an excellent potential to deal with environmental pollution caused by oil spillages in severe environments. The tunable morphology (open and closed pores) and pore sizes were achieved by investigating various parameters like surfactant concentration, amount of external crosslinker, and aqueous phase volume. Droplet sizes of HIPEs were characterized using an optical microscope under different experimental conditions. The influence of pore structure and surface properties of polyHIPE on water contact angle and oil adsorption capacity was also explored. The results indicated that the porous material has an excellent oleophilicity and hydrophobicity, with water contact angles (WCA) up to 146.4°. Additionally, the results presented a noticeable adsorption with a very fast rate towards organic oils from either a water surface or bottom with adsorption saturation achieved in about 120 s. The prepared polyHIPEs showed a good recycling ability; even after 10 adsorption–centrifugation experiments, the adsorption capacity was still more than 85%.

A facile preparation for a series of porous poly(2,2,2-trifluoroethylmethacrylate–divinylbenzene) P(TFEMA–DVB) foams is discussed in this paper.

Hierarchically Porous Calcium Carbonate Scaffolds for Bone Tissue Engineering

Hierarchically porous CaCO₃ scaffolds comprised of micro- (diameter = 2.0 ± 0.3 μm) and nano-sized (diameter = 50.4 ± 14.4 nm) pores were fabricated on silicon substrates using a supercritical CO₂-based process. Differentiated human THP-1 monocytes exposed to the CaCO₃ scaffolds produced negligible levels of the inflammatory cytokine tumor necrosis factor-alpha (TNF-α), confirming the lack of immunogenicity of the scaffolds. Extracellular matrix (ECM) proteins, vitronectin and fibronectin, displayed enhanced adsorption to the scaffolds compared to the silicon controls. ECM protein-coated CaCO₃ scaffolds promoted adhesion, growth, and proliferation of osteoblast MC3T3 cells. MC3T3 cells grown on the CaCO₃ scaffolds produced substantially higher levels of transforming growth factor-beta and vascular endothelial growth factor A, which regulate osteoblast differentiation, and exhibited markedly increased alkaline phosphatase activity, a marker of early osteoblast differentiation, compared to controls. Moreover, the CaCO₃ scaffolds stimulated matrix mineralization (calcium deposition), an end point of advanced osteoblast differentiation and an important biomarker for bone tissue formation. Taken together, these results demonstrate the significant potential of the hierarchically porous CaCO₃ scaffolds for bone tissue engineering applications.

Mesoporous Titania Microspheres with Highly Tunable Pores as an Anode Material for Lithium Ion Batteries

Mesoporous titania microspheres (MTMs) have been employed in many applications, including (photo)catalysis as well as energy conversion and storage. Their morphology offers a hierarchical structural design motif that lends itself to being incorporated into established large-scale fabrication processes. Despite the fact that device performance hinges on the precise morphological characteristics of these materials, control over the detailed mesopore structure and the tunability of the pore size remains a challenge. Especially the accessibility of a wide range of mesopore sizes by the same synthesis method is desirable, as this would allow for a comparative study of the relationship between structural features and performance. Here, we report a method that combines sol-gel chemistry with polymer micro- and macrophase separation to synthesize porous titania spheres with diameters in the micrometer range. The as-prepared MTMs exhibit well-defined, accessible porosities with mesopore sizes adjustable by the choice of the polymers. When applied as an anode material in lithium ion batteries (LIBs), the MTMs demonstrate excellent performance. The influence of the pore size and an in situ carbon coating on charge transport and storage is examined, providing important insights for the optimization of structured titania anodes in LIBs. Our synthesis strategy presents a facile one-pot approach that can be applied to different structure-directing agents and inorganic materials, thus further extending its scope of application.

Hierarchical Fullerene Assembly: Seeded Coprecipitation and Electric Field Directed Assembly

Hierarchical C₆₀ colloidal films are assembled from nanoscale to macroscale. Fullerene molecular crystals are grown via seeded cosolvent precipitation with mixed solvent [tetrahydronaphthalene (THN)/trimethylpyridine (TMP)] and antisolvent 2-propanol. The fullerene solutions are aged under illumination, which due to the presence of TMP reduces the free monomer concentration through fullerene aggregation into nanoparticles. The nanoparticles seed the growth of monodisperse fullerene colloids on injection into the antisolvent. Diverse colloidal morphologies are prepared as a function of injection volume and fullerene solution concentration. The high fullerene solubility of THN enables C₆₀ colloids to be prepared in quantities sufficient for assembly (5 × 10⁸ ). Electric fields are applied to colloidal C₆₀ platelets confined to two dimensions. The particles assemble under dipolar forces, dielectrophoretic forces, and electrohydrodynamic flows. Frequency-dependent phase transitions occur at the critical Maxwell-Wagner crossover frequency, where the effective polarizability of the particles in the medium is substantially reduced. Structures form as a function of field strength, frequency, and confinement including hexagonal, oblique, string fluid, coexistent hexagonal-rhombic, and tetratic.