Waterborne latex films are promising environmentally benign materials for coating and adhesive applications; however, achieving sufficient mechanical strength remains a challenge. We previously developed a reactive latex system composed of hydroxyl group-containing acrylic latex (AL) particles and blocked polyisocyanate (BPI) nanoparticles, which undergo in situ urethane crosslinking through the reaction between hydroxyl and isocyanate groups upon heating. In this study, we systematically examined the effect of the NCO/OH molar ratio, defined as the ratio of isocyanate groups in BPI nanoparticles to hydroxyl groups in AL particles, on the structure formation, thermal transitions, and mechanical behavior of the resulting polyurethane films. Cross-sectional electron microscopy revealed interdiffusion between AL and BPI nanoparticles above their respective glass transition temperatures, leading to homogeneous polyurethane networks. Films prepared with NCO/OH ratios between 0.75 and 1.0 exhibited a well-balanced combination of flexibility and surface hardness, whereas deviations from this range resulted in brittle or excessively soft structures. Films at an NCO/OH ratio of 1.0 also showed high optical transparency and excellent solvent resistance. These results elucidate the structure-property relationships governing crosslinked polyurethane latex films and provide molecular-level insight into designing waterborne coatings.

Research on liquid marbles has historically focused almost exclusively on aqueous systems, establishing a solid foundation for understanding their formation, stability, and applications. Growing interest in soft materials that operate in non-water-based environments has recently shifted attention toward non-aqueous liquid marbles (NALMs). While sharing the same fundamental stabilization principles as aqueous marbles, NALMs provide additional opportunities arising from their broad and versatile solvation capability for diverse solutes, electrical conductivity and enhanced resistance to heat and evaporation. This review offers a comprehensive overview of fabrication methodologies, the variety of liquids and solid particles employed in constructing NALMs, and the interfacial chemistry that governs their behavior. Emerging applications, such as sensing, microreactors and controlled material delivery, are subsequently summarized. Finally, future research directions are outlined to support the continued development of NALMs as a versatile platform for advanced soft materials.

Circularly polarized luminescence (CPL) has emerged as a key optical property with chiral-photonic and optoelectronic applications. However, conventional CPL systems rely on synthetically demanding chiral luminophores that emit at fixed wavelengths, which limits tunability and efficiency. In this study, we demonstrate that achiral or racemic luminophores co-encapsulated with photosensitizers in the helical nanocavities of chiral silica exhibit upconversion CPL (UC-CPL). The chiral silica, which is derived from polymethylvinylsiloxane comprising polyhedral oligomeric silsesquioxane decorated with enantiomeric N-(tert-butoxycarbonyl)cysteine methyl ester moieties (PMVS-POSS-Cys), has a helical structure with a preferred-handedness that facilitates efficient triplet-triplet energy transfer (TTET) and triplet-triplet annihilation (TTA). The resulting materials exhibit distinct CPL and UC-CPL signals when excited at 365 and 532 nm, respectively, despite the achiral nature of the luminophore. This study unprecedentedly demonstrates UC-CPL from achiral emitters within chiral silica matrices, which is achieved through chiral induction in the solid-state helical silica frameworks. The strategy described herein provides a general and versatile platform for developing energy-efficient, wavelength-tunable chiral-photonic materials without the need for elaborate chiral syntheses.

Hydrophobic skins on fruits play a crucial role in preventing dehydration and shielding against environmental stress. Inspired by this natural structure, hydrophobic encapsulation is widely employed to preserve the functionality and long-term stability of hydrogels. However, instability at the interface between hydrophobic shell and hydrogel remains a critical challenge. Here, we present a hydrogel encapsulation strategy to stabilize the incompatible interface using a concept of liquid marble, where liquid droplet is covered with hydrophobic particles. A uniform nonpolar liquid layer is first formed on the hydrogel surface through interfacial bridges with hydrophobic particles. A secondary hydrophobic particle layer is then deposited onto this liquid layer to prevent leakage, yielding a multi-layered marble (MLM) structure. This MLM-encapsulation is highly versatile, accommodating various hydrogels, liquids, and structural configurations. By maintaining hydrogel performance and functionality across diverse applications, MLM-encapsulation provides a universal and robust solution for overcoming the long-standing interfacial instability problem.

IntroductionGas marbles have recently emerged as a new class of particle-stabilized gas–liquid systems. A gas marble consists of a single air bubble suspended in air and encapsulated by a thin liquid shell stabilized by solid particles, forming an air-in-liquid-in-air structure. Gas marbles can be generated using various edible particles, but their formation has so far been demonstrated almost exclusively in water, where only particles with intermediate wettability (moderately hydrophilic contact angles) lead to stable structures. Because liquid surface tension strongly influences the three-phase contact angle, expanding gas-marble formation beyond water requires understanding how the liquid phase governs gas marbles formation and stability.MethodsIn this work, we investigate the formation of gas marbles using cocoa particles and a wide range of edible liquids differing in surface tension and composition. We also systematically varied a model liquid phase from water/ethanol mixtures. Unlike previous studies that focused primarily on particle wettability in water-based systems, this work explicitly isolates and elucidates the role of the liquid phase in governing gas-marble formation.Results and discussionWe demonstrate that the three-phase contact angle can be tuned through liquid surface tension, enabling or inhibiting gas-marble formation. We show, for the first time, that stable cocoa-based gas marbles can be produced in a broad set of edible liquids, provided that the liquid surface tension remains sufficiently high (above 34 mN/m). These gas marbles exhibit notable robustness, including heat resistance and long-term stability. Overall, this study establishes clear criteria linking liquid surface tension, particle wettability, and gas-marble formation. These findings provide new physical insight into particle-stabilized gas–liquid interfaces beyond water systems and offer general formulation guidelines applicable across a wide range of edible and non-aqueous liquids.

This study demonstrates a sustainable CO2-capture platform based on liquid marbles (LMs) stabilized with hydrophobized biochar (BC-FDTS) particles and containing a CO2-reactive natural deep eutectic solvent (NaDES). The BC-FDTS particles formed porous shells around NaDES droplets, enabling stable and mobile LMs with efficient gas-liquid contact. LMs absorbed CO2 2.5 times faster than bulk NaDES under identical conditions, owing to their high interfacial area. Moreover, the LMs retained structural integrity and CO2 uptake performance over multiple absorption cycles. These results highlight biochar-stabilized NaDES LMs as a promising, nature-derived platform for next-generation, sustainable CO2 capture technologies.

Nonspherical hydrogel particles offer unique anisotropic properties and functionalities that are inaccessible to conventional spherical hydrogels. However, achieving precise shape control without complex fabrication equipment or organic solvents remains a major challenge. Herein, we present a solvent-free and template-guided strategy for synthesizing nonspherical hydrogel particles using polyhedral liquid marbles (LMs) as reaction vessels. The polyhedral LMs were constructed by assembling millimeter-sized hydrophobic solid polymer plates around droplets of poly(ethylene glycol)-based vinyl monomers containing a photoinitiator. Upon UV irradiation, free radical polymerization proceeded efficiently inside the confined droplets, yielding gel particles whose shapes directly reflected the LM geometries, including cubic, tetrahedral, octahedral, dodecahedral, and icosahedral forms. Furthermore, the degree of swelling in water was finely tunable by varying the cross-linking density of the gel network, while the incorporation and removal of NaCl particles enabled the formation of a multihollow internal structure. As a proof of concept, cubic hydrogel particles exhibited a swelling-induced mechanical function, where water absorption was converted into macroscopic mechanical work capable of lifting an external object, demonstrating the mechanical advantage of shape-defined hydrogels. The LM-based method allows for geometrically defined, solvent-free synthesis of anisotropic hydrogel particles using simple procedures without specialized apparatus or organic solvents. The proposed approach provides a versatile platform for producing shape-programmable soft materials that may find applications in soft robotics, stimuli-responsive systems, and 3D hydrogel assemblies.

Gas marbles (GMs) are a family of particle-stabilized soft dispersed systems with a soap bubble-like air-in-water-in-air structure. Here, we investigate the effect of the stabilizing particle size on the resulting structure and properties of GMs. We synthesize a series of polystyrene particles with diameters between 2 and 1050 μm by dispersion polymerization and seeded dispersion polymerization. We surface-modify these particles with a poly[2-(diethylamino)ethyl methacrylate] polymeric steric stabilizer to enable interfacial adsorption to the air/water interface. This set of particles enables us to form GMs and isolate the effect of particle size on the GM formation and stabilization efficiency. We find that particles with sizes ≥80 μm adsorb as a particle monolayer to the surface of the GM, while smaller particles adsorb as ill-defined, multilayered aggregates. These results indicate that the force balance between particle-particle interaction and gravity is an important parameter to control the surface structure of the GMs. Furthermore, the degree of hexagonal ordering increases monotonically with particle size, reflecting enhanced packing regularity for larger particles. The assembly structure and size of the particles also correlate with the mechanical integrity of the GMs against fall impact. The mechanical resistance is governed by the gap between the inner liquid of the GM and the supporting substrate, as well as by the associated potential energy, both of which depend on particle size. In summary, our study systematically explores structure-property-performance relationships connecting the stabilizing particle size with the interfacial structure and the resultant mechanical stability of the macroscopic GM.

Imaging of invisible mechanical stresses is a significant challenge in a variety of fields. 2D distribution imaging of compression stresses applied by irregularly shaped 3D objects is not achieved using conventional sensing materials and devices. In the present work, such a compression-stress distribution in the range of 0.1 kPa-5 MPa is imaged using 3D transparent silicone rubber containing stimuli-responsive color-changing conjugated polymer, layered polydiacetylene (PDA). Compression-responsive capsules, liquid droplets surrounded by solid particles, collapse with compression on the rubber. The outflowed interior liquid containing polyethyleneimine (PEI) oligomer is diffused into the bulk rubber through the free volume space of the rubber matrix. PEI serves as a guest for intercalation into the interlayer space of the layered PDA, i.e. chemical stress, directing the blue-to-red color change. As the red-color intensity increases with increasing applied compression stress, the strength is colorimetrically quantified. The transparent 3D device enables 2D distribution imaging of the compression stresses applied by irregularly shaped 3D objects in the millimeter to the centimeter scales. The device design can be applied to achieve 2D stress-distribution imaging in various length scales and strength ranges.

Abstract An adhesive film composed of acrylic latex particles and blocked polyisocyanate nanoparticles is developed as a water-borne, thermally reactive system. The adhesive film exhibits sufficient mobility, enabling intimate contact with adherend surfaces, and subsequently hardens through formation of urethane crosslinking upon heating. High adhesive strength is achieved for solvent-sensitive polymer substrates (eg polycarbonate and poly[ethylene terephthalate]), whose critical surface tension values are close to that of the adhesive film.

Core/shell particles have been synthesized using a seeded dispersion/emulsion polymerization strategy, which enables the controlled deposition of a polymer shell around preformed seed particles. The seeded dispersion/emulsion polymerization developed is a versatile method toward the core/shell particles but has been so far conducted in liquid media in the presence of a colloidal stabilizer, which is required for realization of colloidal stability during polymerization. In this study, we developed solvent-free seeded dispersion polymerization without any colloidal stabilizer. Specifically, polypyrrole (PPy) shells were successfully formed on micrometer-sized cubic sodium chloride (NaCl) seed particles by solvent-free oxidative seeded dispersion polymerization of the pyrrole (Py) monomer. The Py monomer, oxidant, and NaCl seed particles were separately placed in a sealed reactor, allowing Py vapor to diffuse and polymerize selectively on the surface of the seed particles. The resulting NaCl/PPy core/shell particles exhibited a uniform morphology with a controllable PPy shell thickness depending on the polymerization time. Subsequent dissolution of the NaCl cores in water led to the formation of PPy microcapsules while preserving the original cubic geometry of the seeds. To evaluate the versatility of this method, other water-soluble salts with different shapes, including potassium chloride, magnesium chloride, calcium chloride, and aluminum chloride, were employed as alternative templates. The results demonstrated that this approach enables the fabrication of not only core/shell particles/microcapsules with cubic shapes but also those with various shapes depending on the template used.

Waterborne latex films are an essential material in coating, print, and adhesive industries. There have been continuous researches on introduction of cross-linked structures to the latex films to improve their mechanical properties. In this study, we develop latex film fabricated from aqueous dispersion of hydroxy group-containing acrylic latex particles (AL particles) as a base film-forming material and blocked polyisocyanate nanoparticles (BPI nanoparticles) as a crosslinker. Electrophoretic light scattering, transmission electron microscopy and attenuated total reflection-infrared studies indicate that AL particles and BPI nanoparticles do not interact with each other and exist independently in aqueous media, and that removal of water from the dispersion via drying at 25 degrees C causes the particles to contact each other, generating a blend film. Furthermore, heating of the blend film at 90 degrees C, above the glass transition temperatures of the AL particles and BPI nanoparticles, leads to interdiffusion of the AL and BPI components. Formation of crosslinking is realized by heating at 140 degrees C via urethane bond formation between hydroxy groups in AL and isocyanate groups generated from BPI by release of blocking agents. Tensile tests, scratch hardness tests and surface hardness measurements confirm that mechanical property of the films is improved via urethane-based crosslinking.

Hypothesis Three-phase water contact angle is a key parameter in the stabilization of particle-stabilized foams and emulsions. Gas marbles, which are particle-stabilized bubbles suspended in gas phase, are expected to be similarly influenced by the three-phase water contact angle. We hypothesize that the ability of particles to form gas marbles is strongly dependent on this parameter. Experiments We investigated the ability of various edible particles with different sizes, shapes, and compositions to form gas marbles. For each particle, we examined gas marble formation, measured the three-phase water contact angle, and assessed the structure and stability of the resulting gas marbles. Findings Our results show that gas marble formation is critically dependent on the three-phase water contact angle on particles. Three distinct groups emerged: (1) Hydrophobic particles (high contact angle): No gas marble formation occurred, the air bubbles burst in the contact of the particles layer; (2) Highly hydrophilic particles (low contact angle) also failed to form gas marbles, as their strong affinity to water prevented stabilization at the air/water surface; (3) Moderately hydrophilic particles (intermediate contact angle) leading to successful gas marble formation. Our results indicate that an optimal range of three-phase water contact angle is essential for gas marbles formation whatever the particles size and shape. This study, for the first time, highlights the critical role of this parameter in the stabilization of gas marbles. The resulting gas marbles showed remarkable stability, including resistance to drying and heating and also mechanical resistance, highlighting their potential applications in edible materials.

The transport of microliter-scale droplets on solid surfaces is critical for various applications, including microfluidics and microengines. Recently, droplet manipulation strategy using thermocapillary convection has received attention due to its precise and remote controllability. The mobility of liquid droplets in this method depends on several parameters, such as laser power and the light absorption coefficient. Additionally, surface tension significantly influences droplet movement although its underlying mechanism remains unclear. In this study, we investigate the effect of surface tension on droplet movement via thermocapillary convection. Aqueous dispersions of polypyrrole (PPy) nanoparticles (NPs), which absorb near-infrared (NIR) light and convert it into heat, are employed as droplets. Upon NIR laser irradiation, the PPy droplets generate localized heat, resulting in thermocapillary convection. The lubricated surface (LuS) is used as a substrate. Due to the mobile lubricant layer, droplets are easy to move with low friction. Surface tension is modified by adding a surfactant, and the droplet movement speed increases with decreasing surface tension. Here, this phenomenon is investigating the parameters acting to Marangoni force: contact line length and surface tension gradient. We confirm that the Marangoni force, which propels the droplet, is induced more effectively by low surface tension liquids. This study provides fundamental insights into droplet behavior governed by wettability differences, advancing droplet manipulation techniques for diverse fluidic systems.

Surface-templated evaporation-driven (S-TED) synthesis, a technique for producing supraparticles by drying colloidal dispersion droplets on liquid-repellent surfaces, offers numerous advantages over conventional solvent-based synthesis methods. For example, the S-TED method requires no toxic solvent, heating, or additional purification steps. Moreover, this approach allows precise control of supraparticle porosity and size with a narrow size distribution. However, despite extensive efforts, only a limited range of supraparticles shapes with different curvatures have been fabricated. This work introduces a novel approach for three-dimensional manipulation of supraparticle shapes using multiple liquid-repellent surfaces as drying templates. Thin polyethylene terephthalate (PET) plates with varied wettable surfaces and shapes are used as templates. Droplets covered by the PET plates evaporate in two different modes, involving constant contact line or constant height. These modes considerably influence the shape of supraparticles. In the constant contact line mode, the shape of the PET plates determines the supraparticle shape. In addition, polyhedral shapes can be precisely fabricated by varying the numbers of the PET plates, broadening the range of achievable supraparticle shapes.

Surfactant-free coupling polymerization of pyrrole (Py) and its derivatives, namely, N-methylpyrrole (MPy) and N-ethylpyrrole (EPy), was conducted using solid Fe(NO3)3 in the presence of an aqueous medium, resulting in aqueous dispersions of polymer particles. Dynamic light scattering studies revealed the production of colloidally stable polymer nanoparticles with diameters of 153-206 nm, 262-294 nm and 273-278 nm in aqueous media for the Py, MPy and EPy systems, respectively. The particle sizes of poly(N-methylpyrrole) (PMPy) and poly(N-ethylpyrrole) (PEPy) were larger than those of polypyrrole (PPy), which could be due to the greater hydrophobicity of MPy and EPy than Py. The particles could achieve colloidal stability through an electrostatic stabilization mechanism, as the polymerization process introduces cationic charges to the polymers via doping. Larger amounts of hydroxy and carbonyl groups were introduced into PMPy and PEPy because of the easier overoxidation of MPy and EPy due to their lower redox potentials than that of Py. Furthermore, the resulting particles could adsorb on oil-water interfaces and work as effective Pickering-type emulsifiers. Suspension polymerization of vinyl monomer-in-water Pickering emulsions stabilized with PPy and PMPy nanoparticles resulted in the production of nanoparticle-coated polymer microparticles with diameters of 25 mu m and 154 mu m, respectively.

CS₂ is produced by the reaction of sulfur with carbon-based materials such as charcoal and methane, which are widely available and cost-effective. Consequently, utilizing CS₂ as a precursor for functional materials can promote the advancement of sustainable industries. For instance, electrically conductive poly(carbon sulfide)s (PCS) are synthesized via the polymerization of CS₂, and their potential application as cathode materials for Li-ion batteries has been explored. PCS films can be fabricated by gas-phase polymerization of CS₂ under UV or plasma irradiation. 1 However, these reactions are difficult due to the high flammability and toxicity of CS₂ gas. Alternatively, reduction polymerization of CS₂ in organic solvents has been reported as a more feasible approach compared to gas-phase polymerization. Nevertheless, this method requires an equimolar or greater amount of Na as a reductant. To develop a safer and easier polymerization of CS₂, we previously reported the electroreductive polymerization of CS₂ in acetonitrile solution, eliminating the need for hazardous reducing agents. 2 Moreover, the resulting PCS demonstrated potential as a cathode material for Li-ion batteries. However, PCS exhibits poor processability due to its insolubility and infusibility. To enhance its processability, we investigated the synthesis of PCS particles by electroreductive polymerization of CS₂ under stirring conditions (Scheme 1). Electroreductive polymerization was performed via constant current electrolysis at 50 mA cm⁻², 100 mA cm⁻², and 200 mA cm⁻², with stirring at 450 rpm in an acetonitrile solution containing 0.18 M Bu₄NBF₄, using a glass cell equipped with a water-cooling jacket. A platinum plate (1 × 1 cm²) and a platinum wire ( Φ = 0.5 mm) were used as the working and counter electrodes, respectively. After polymerization, PCS particles were deposited at the bottom of the cell and subsequently purified by centrifugation with methanol and water. The PCS particles were obtained as a brown solid with a yield of 14.5%. The particle size distribution estimated by laser diffraction (LD) measurement was narrower than that of PCS synthesized without stirring, and the particle size decreased as current density increased. This phenomenon is probably attributed to the rapid formation of multiple cores of polymer particles at higher current densities. In the optical microscope image of the aqueous dispersion of PCS particles, the particles prepared under stirring were smaller and more uniform than those synthesized without stirring. The resulting polymer particles exhibited electrical conductivity after doping by iodine. (1) R. K. Sadhir, K. F. Schoch, Chem . Mater . 1996 , 8 , 1281. (2) Y. Matsumura, B. Ochiai, Chem . Lett. 2021 , 50 , 1856. Figure 1

Simple and environmentally friendly synthetic method of polypyrrole (PPy) microtubes were proposed. First, sucrose microfibers coated by PPy overlayer were synthesised by solvent-free vapor-phase coupling polymerization of pyrrole (Py) monomer using solid oxidant in the presence of sucrose microfibers with a diameter of approximately 4 μm without any liquid media. Next, selective extraction of sucrose core component from the sucrose-core/PPy-sheath microfibers using water resulted in the formation of PPy microtubes. The sheath thickness of PPy microtubes increased from 168 nm to 209 nm by controlling relative humidity during the polymerization from 10 to 40