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Introduction: The purpose of this study is to assess the real-life efficacy and tolerance of a new preservative-free, surfactant-free latanoprost (PFSF-LAT) formulation. Methods: Retrospective, multicentre, non-comparative, observational study in patients with ocular hypertension or open angle glaucoma, naïve or non-naïve to previous intraocular pressure (IOP)-lowering treatment, and treated for at least 3 months with the study eye drop. IOP for worse eye, ocular signs and symptoms, and concomitant use of artificial tears were collected at study drug initiation and at last visit under treatment. Reasons for discontinuing the study eye drop (if relevant) and investigators' satisfaction were also assessed. Results: In the per protocol population (103 eyes; 63 naïve, 39 switched, 1 not classified because of missing data), IOP decreased significantly (p < 0.001) from 21.6 ± 5.0 mmHg at baseline to 16.1 ± 3.5 mmHg at the end of the study (mean reduction of − 5.5 ± 4.6 mmHg; − 25.5%). IOP in naïve patients was significantly improved, with a mean reduction of 7.1 mmHg (− 30.7%), which was within expected latanoprost IOP-lowering effect. Interestingly, in previously treated patients, switching to PFSF-LAT also allowed for a further 2.9 mmHg decrease in IOP (p < 0.001). The incidence of ocular side effects at study initiation was significantly (p < 0.001) reduced from 31.1% to 11.3% in the overall population, and from 65.0% to 7.5% in switched patients. This included conjunctival hyperaemia and superficial punctate keratitis (from 42.5% to 2.5% and from 37.5% to 2.5% in switched patients, respectively). According to investigators, tolerance and efficacy of the study eye drop were satisfactory or very satisfactory in 98.1% and 83.2% of patients, respectively. Conclusion: PFSF-LAT is an efficient treatment for patients with glaucoma with an improved tolerance profile. It can be considered as initial therapy in naïve patients or in patients with poor ocular tolerance to previous IOP-lowering eye drops. [ABSTRACT FROM AUTHOR]

The chemical/physical properties and reliable performance of nanoporous materials are strongly influenced by the particle size and corresponding distribution. Among many types of MOFs, ZIF‐8, is still widely used and many studies have been conducted to control the particle size and uniformity of ZIF‐8 using surfactants and organic solvents. However, the use of surfactants and organic solvents process is expensive and may cause environmental pollution. For the first time, in this paper, a surfactant‐free, size‐controllable, and scalable green synthesis method of ZIF‐8 particles is reported using four reaction parameters (temperature, concentration, pouring time, and reactant ratio) that affect the formation of nuclei and growth of ZIF‐8 crystals. The as‐synthesized ZIF‐8 nanoparticles show great uniformity and controllable particle sizes in the wide range of 147–915 nm. In addition, a 2 L large‐scale synthesis of ZIF‐8 with narrow size distribution is developed by finely tuned particle size in water without any additives. To demonstrate the efficient utilization of nanopores according to the particle size and size distribution, an adsorption test is conducted on the ZIF‐8 nanoparticles. This study will support the synthesis of size‐controlled ZIF‐8 with narrow size distribution and their composites for achieving high performance in the emerging applications. [ABSTRACT FROM AUTHOR]

Size effect of Pt nanoparticle (NPs) on electrocatalysis should be investigated in a wide size range and a narrow distribution. The surfactants used for size control were detrimental to exploring size effect. However, the largest size of Pt colloidal NPs was limited to ∼5 nm without surfactant, which is insufficient for investigating size effect. In this work, surfactant-free Pt colloidal NPs with a wider size range from 1.8 to 10.0 nm were synthesized by controlling the ratio of NaOH and Pt salts in the ethylene glycol by oil-bath heating. Assisted by the precise control of Pt size, the size effect on the electrooxidation of CO, methanol and ethanol was studied, showing that the optimal size varied from the specific catalytic reaction. The synthesis extended the upper limit of large Pt NPs by surfactant-free method, showing potentials in preparing other precious metal NPs with a wide size range. [Display omitted] • Wide size range synthesis of surfactant-free colloidal Pt nanoparticles in alkaline ethylene glycol. • Water accelerates the rate of particle formation. • Temperature increases the conversion of Pt precursor rather than the size. • The wide range is sufficient to study size effect on electrocatalysis. [ABSTRACT FROM AUTHOR]

This study aims to prepare a surfactant-free, stable CNT nanofluid to be used as secondary refrigerant. Antifreeze having EG/water was chosen as a basefluid. The nanofluid was prepared by two different methods. Firstly, the nanofluid was prepared by dispersing CNT in EG/water mixture named as CNT (EG/water) nanofluid. In the second method, CNT was dispersed in EG followed by addition of water named as (CNT-EG)/water nanofluid. Sonication time study revealed 4.30 h and 80 min as optimum sonication time for preparation of CNT (EG/water) and (CNT-EG)/water nanofluid, respectively. (CNT-EG)/water nanofluid was more stable (145 days) as compared to CNT (EG/water) nanofluid (130 days). It was found by FTIR and NMR spectroscopy that in (CNT-EG)/water nanofluid, EG interacts with CNT through trans conformation that results in higher interaction and better stabilization. As the concentration increases, thermal conductivity increases in both the nanofluids in comparison to basefluid. However, higher enhancement was observed in case of (CNT-EG)/water nanofluid. Viscosity augmentation is higher in CNT (EG/water) (19%) as compared to (CNT-EG)/water (15%) nanofluid at shear rate 100 s−1. Thus, preparing (CNT-EG)/water nanofluid by dispersing CNT in EG followed by addition of water is an economical and time saving method for producing stable nanofluid instead of dispersing CNT directly into mixture of EG/water. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is increasing interest in the development of oleogel‐based emulsions. However, they usually contained surfactants for stabilization, especially small‐molecular weight surfactants, which may have adverse health impacts. RESULTS: Herein, a surfactant‐free oleogel‐based emulsion stabilized by co‐assembled ceramide/lecithin (CER/LEC) crystals was developed. The formation and stabilization mechanisms were explored. The different molar ratios of gelator (LEC and CER) in emulsions resulted in different crystal morphology, crystallinity as well as different emulsion properties. This suggested that appropriate crystallinity, crystal size, and interfacial distribution of these crystals provided higher surface coverage against droplets coalescence, thus better emulsion stabilization. Both X‐ray diffractograms and contact angle results confirmed that the crystals which were primarily responsible for emulsion stabilization, are co‐assembled crystals consisted of both gelators (CER and LEC). Furthermore, the percentage of free fatty acids (FFAs%) results revealed a negative relationship between lipid digestibility and crystal concentration. CONCLUSIONS: This strategy greatly enriched surfactant‐free oleogel‐based emulsion formulations, as well as their potential applications in healthy lipid‐based products and novel food delivery systems with controlled lipid digestibility. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

A room temperature surfactant-free synthesis of gold nanoparticles in the size range 10–20 nm that only requires HAuCl4 as the precursor, NaOH as the base, water as the solvent and a mono-alcohol such as methanol or ethanol as the reducing agent, has recently been detailed. This approach is promisingly simple to obtain colloids stable for months. Here, it is shown that the use of fresh stock solutions of base is one key to ensure the formation of stable surfactant-free small-sized gold nanoparticles. The need for relatively freshly prepared stock solutions of base does not appear to be as crucial for syntheses using stabilizers and/or viscous solvents such as glycerol. The possibly overlooked importance of the age of the stock solution of base might account for the limited interest to date for the simple room temperature synthesis in low viscosity mono-alcohols highlighted. [ABSTRACT FROM AUTHOR]

Curcumin has been used in many diseases due to its high therapeutical potential in recent years. Although curcumin is a frequently used natural polyphenolic compound products, its low solubility and poor permeability limits the dermal efficacy of curcumin. Emulgels are a new generation of semi-solid formulations that combine the advantages of both emulsions and gels. The biggest limitation of emulsions is surfactant related irritation problems caused by the use of high amount of surfactants. In this study, it was aimed to increase the skin permeability of curcumin by developing surfactant-free emulgel formulations. In the study, emulgels were developed by Carbopol 940 gels as the aqueous phase, olive oil and curcumin methanol solution as the oil phase. No surfactant was used additionally to show the stabilizing effect of Carbopol in emulgels. The emulgel formulations were subjected to physicochemical characterization by means of organoleptic properties, pH, rheological and mechanical properties. Mechanical properties were carried out by texture profile analyzes to determine the structure related properties such as hardness, compressibility, adhesiveness, cohesiveness and elasticity. The spreadability of the formulations was also determined with Texture Analyzer. Obtained emulgels showed good rheological, mechanical and spreadability properties. The transdermal permeation of the chosen emulgel was studied ex vivo against hydrogel prepared with the same amount of Carbopol. The emulgel formulation significantly increased transdermal permeation compared to the hydrogel. This emulgel formulation successfully passed from stress tests. As a conclusion, the novel surfactant-free emulgel formulation was successfully developed to increase curcumin permeation through the rat skin. [ABSTRACT FROM AUTHOR]

High internal phase emulsion (HIPE) templating is a well-established method for the generation of polymeric materials with high porosity (>74%) and degree of interconnectivity. The porosity and pore size can be altered by adjusting parameters during emulsification, which affects the properties of the resulting porous structure. However, there remain challenges for the fabrication of polyHIPEs, including typically small pore sizes (∼20–50 μm) and the use of surfactants, which can limit their use in biological applications. Here, we present the use of gelatin, a natural polymer, during the formation of polyHIPE structures, through the use of two biodegradable polymers, polycaprolactone-methacrylate (PCL-M) and polyglycerol sebacate-methacrylate (PGS-M). When gelatin is used as the internal phase, it is capable of stabilising emulsions without the need for an additional surfactant. Furthermore, by changing the concentration of gelatin within the internal phase, the pore size of the resulting polyHIPE can be tuned. 5% gelatin solution resulted in the largest mean pore size, increasing from 53 μm to 80 μm and 28 μm to 94 µm for PCL-M and PGS-M respectively. In addition, the inclusion of gelatin further increased the mechanical properties of the polyHIPEs and increased the period an emulsion could be stored before polymerisation. Our results demonstrate the potential to use gelatin for the fabrication of surfactant-free polyHIPEs with macroporous structures, with potential applications in tissue engineering, environmental and agricultural industries.

This mini review critically discusses self-assembled mesoscale structures (dimensions between molecular and macroscopic) forming in multicomponent mixtures comprising 1) liquids or 2) liquids and solids or 3) liquids and gases. The common feature of the discussed structures is absence of surfactants. Covered are solvophobicity-driven mesoscale structures (including metastable ouzo-type particles with finite lifetimes), surfactant-free microemulsions, and bulk nanobubbles. The emphasis is mainly on critical analysis of experimental data and suitability of available experimental methods with focus on unambiguous differentiation between various types of mesoscale structures.

Electrodes composed of nanostructured surfaces have been shown to be promising electrocatalysts, offering enhanced catalytic activity. Gold nanoparticles (AuNPs) are often used to produce such a nanostructured surface. However, these are commonly prepared using a reductant and surfactant, often hindering the electrocatalytic application of the surface. In the present study, we fabricated a nanostructured gold thin film electrode derived from a solution of AuNPs containing only Au, H, and O, which was prepared by solution plasma processing in the presence of hydrogen peroxide. The concentrated AuNP dispersed aqueous solution was dropped onto the glassy carbon substrate and then dried to form a AuNP thin film at room temperature. The resultant gold film was nanostructured owing to the presence of the AuNPs, could be used directly in electrochemical reactions without pre-treatment (such as surfactant/reductant removal), and gave stable voltammetric responses, indicating its suitability as an electrode material. In addition, the AuNP thin film electrode exhibited enhanced electrocatalytic activity compared with conventional planar gold electrodes, which can be attributed to its surface nanostructure. In particular, the electrocatalytic current in the hydrogen evolution reaction was more than 10 times larger at the nanostructured AuNP thin film electrode than at a planar gold electrode. Further, the AuNP thin film electrode enabled direct electron transfer (DET) between a redox enzyme, neuroglobin, and the electrode surface, while the planar electrode showed no DET response. The results indicate the usefulness of the present AuNP thin film electrode, prepared by a reagent-free process, for various electrocatalytic applications.

Emulsions have a range of applications, for example, in cosmetics, pharmaceuticals, and food. However, the surfactants used to prepare such emulsions can often be toxic to humans and the environment and also affect the oil properties of emulsions. Therefore, interest in surfactant-free emulsions has increased in recent years. One method to enhance emulsion stability without a surfactant is to use a gelling agent to increase the viscosity. Gelling agents are viscous hydrocolloids that gel when dispersed in water, even at low concentrations. In this study, we prepared six oil-in-water emulsions (oil content 20%) with different gelling agents (xanthan gum, Carbopol 981, TR-2, and Ultrez 20) and investigated the effect of the gelling agent concentration. For each sample, particle size and emulsion stability analysis were performed at high temperatures to ensure the stability of the emulsions. We observed that the emulsion prepared using TR-2 (0.25 wt%) did not aggregate at high temperatures for one month. Based on our assessment of the stability of these emulsions under various conditions, we believe that the use of gelling agents for the preparation of surfactant-free emulsions shows great promise for applications requiring long-term stable emulsions, such as cosmetics and medicine. [ABSTRACT FROM AUTHOR]

Hydrogen generation in electrostatically stabilized, aqueous organic nanoparticle dispersions is investigated. For this purpose, organic nanoparticle dispersions are synthesized in water by nanoprecipitation from tetrahydrofuran and stabilized by charging through strong molecular electron acceptors. The dispersions are stable for more than 10 weeks on the shelf and during the photocatalytic process, despite the continuous transfer of charges between the reactants. The hydrogen generation in the electrostatically stabilized dispersions outperforms the hydrogen generation in organic nanoparticle dispersions which contain the common stabilizer sodium dodecyl sulfate., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Surfactant-free colloidal syntheses in aqueous media are attractive to develop nanomaterials relevant for various applications, e. g. catalysis or medicine. However, controlled green syntheses without surfactants of metal nanoparticles in aqueous media remain scarce. Here, room temperature syntheses of gold (Au) nanoparticles (NPs) that require only HAuCl 4 , alkaline water and an alcohol, i. e. relatively benign chemicals and mild reaction conditions, are developed. The findings of a comprehensive multi-parameters screening performed in small volumes (<3 mL) over 1000+ experiments pave the way to greener high throughput screenings of large parametric spaces and lead to scalable (100 mL) synthetic strategies. A rational selection of the alcohol is proposed. The influence of lights with defined wavelengths (222-690 nm) is investigated. It is found that lights with lower wavelengths favor the formation of smaller 5 nm NPs. Different kinetics and formation pathways are observed for different alcohols and for lights with different wavelengths. The sensitivity to various experimental parameters increases with the alcohol used in the order glycerol

An attempt has been made to combine interfacial polymerization with a fast mixing technique without the use of surfactant. Effects of mixing speed, reaction time, temperature, oxidant-to-monomer molar ratio and nitric-to-monomer molar ratio were tested for electrical conductivity and polyaniline nanofiber size. The findings demonstrate that the diameter of polyaniline nanofiber can be reduced by optimising the synthesising parameter, thereby increasing the electrical conductivity of polyaniline nanofiber. Infrared spectroscopy has shown increased amplitude of the main absorption peak of polyaniline nanofiber during the conversion of aniline to conductive polyaniline nanofiber. The crystalline nature of polyaniline nanofiber has been discovered by the X-ray diffraction spectra. Hall effects experiments have shown that the electrical conductivity of polyaniline nanofiber has improved from 5.2 to 17.5 Scm−1 with an increase in homogenizer speed. The morphological properties of polyaniline nanofiber through electron microscopy scanning have confirmed the decreasing size of polyaniline nanofiber from 50-60 nm to 20–30 nm by increasing the homogenizer speed to 30,000 rpm. These findings demonstrate that higher homogenization speed can split the solution to smaller molecules during polymerization contributing to the creation of smaller nanofiber sizes.

Hollow microparticles are important materials, offering a larger surface area and lower density than their solid counterparts. Furthermore, their inner void space can be exploited for the encapsulation and release of guest species in a variety of applications. Herein, we present phosphazene-based silica hollow microparticles prepared via a surfactant-free sol-gel process through self-assembly of the alkoxysilyl-containing polymer in water–ethanol solution. Solely, a silane-derived polyphosphazene was used as the precursor for the microparticle formation, without additional classical silica sources. These novel hollow silica-based microparticles were prepared without surfactant, using a designed amphiphilic polyphosphazene for the particle formation made by two components, a hydrophilic unit consisting of 3-mercaptopropyl(trimethoxysilane), and a hydrophobic unit (dodecanethiol) attached to the double bonds from the poly(allylamine)phosphazene backbone via a thiol-ene photoreaction. Due to these two functionalities, a "vesicle"-like self-assembled structure was formed in the reaction medium, which could be then utilized for the microparticle preparation. The influence of NaOH during the synthesis was shown to affect the size and the wall thickness of the microparticles. This effect may enhance the possibilities to tailor such microparticles for drug delivery purposes or for future controlled release of other substances, such as drugs, fragrances, or anticorrosive pigments. [ABSTRACT FROM AUTHOR]

Automation is promising to investigate in detail the effect(s) of parameters that influence the synthesis and properties of nanomaterials. However, it remains challenging to automate even selected key-steps of most wet-chemical syntheses of nanoparticles. Here, a simple, affordable, yet modular, automated station reported for the synthesis of chemicals is adapted to study nanomaterial syntheses, to timely screen larger multi-parameter spaces, to gain a deeper knowledge and awareness on parameters to control, to ultimately achieve more reproducible and sustainable syntheses. As a case study, this automated station is implemented to investigate and develop surfactant-free gold nanoparticles obtained at room temperature in alkaline water-alcohol mixtures. It is shown that the NaOH/Au molar ratio is a to-be-preferred descriptor to control the optical properties and size of the gold colloids for surfactant-free glycerol-mediated syntheses. Size control is simply achieved by carefully tuning the glycerol content and/or amount of base. For ethanol-mediated synthesis, the NaOH/Au molar ratio is also a suitable knob to control the nanoparticle properties. The results pave the way to higher throughput nanoparticle syntheses, ultimately relevant to timely build the missing larger datasets relevant for artificial intelligence, to one day routinely achieve the self-driven discovery of new nanomaterials and their related synthesis. [Display omitted] • An automatic synthesis machine is developed for colloidal nanoparticle synthesis. • Alcohol-mediated syntheses of surfactant-free gold nanoparticles are studied. • A large parameter space is rapidly screened. • The NaOH/Au molar ratio is shown to be a key experimental parameter. • The results pave the way to higher throughput nanoparticle syntheses. [ABSTRACT FROM AUTHOR]

A room temperature surfactant-free synthesis of gold nanoparticles in the size range 10–20 nm that only requires HAuCl4 as the precursor, NaOH as the base, water as the solvent and a mono-alcohol such as methanol or ethanol as the reducing agent, has recently been detailed. This approach is promisingly simple to obtain colloids stable for months. Here, it is shown that the use of fresh stock solutions of base is one key to ensure the formation of stable surfactant-free small-sized gold nanoparticles. The need for relatively freshly prepared stock solutions of base does not appear to be as crucial for syntheses using stabilizers and/or viscous solvents such as glycerol. The possibly overlooked importance of the age of the stock solution of base might account for the limited interest to date for the simple room temperature synthesis in low viscosity mono-alcohols highlighted.

Pt‐based alloy nanoparticles are critical electrochemical catalysts for the water oxidation and oxygen reduction reactions. But the surfactants adsorbed on the nanoparticles' surfaces are hard to remove off, blocking the catalytic active sites and decrease the catalysis activity of the alloy catalysts. Herein, we engineered surfactant‐free PtCu alloy polyhedral nanospheres with foam‐like surfaces in pure water at 40°C directly. Metal precursors were reduced by ascorbic acid. The sizes of polyhedral nanospheres were formed by assembling of tiny PtCu alloy nanoparticles in the sizes of 4.2 ± 0.70 nm, resulting the larger nanospheres in the sizes of 124 ± 30 nm. Underpotential deposition of copper atoms occurred, which catalyzed reductions of Pt precursor and depositions of Pt atoms, high yields of Pt component in PtCu alloy nanospheres and fast reaction rate for reductions of Pt precursors were achieved. Common transition metal, Fe, Co, Ni was also investigated. Only Fe atoms were alloyed with Pt crystals, but the contents of Fe were lower than those of Cu in PtCu alloy. Due to the alloyed structures and special surface structures, PtFe and PtCu exhibited 12.8% and 87% higher current densities toward water oxidation reaction and oxygen reduction reactions in acidic medium than those of commercial Pt black, respectively. This work provides us a new way to get surfactant‐free PtM (M = Cu, Fe, etc) alloy nanoparticles which were produced in water. It is significant to achieve the advanced electrocatalysts with clean surfaces and high catalytic activities. [ABSTRACT FROM AUTHOR]

While triboelectric nanogenerators (TENGs) made of biomaterials are becoming significant components of self-charged monitoring healthcare systems, most of them show low output performance and poor durability. Herein, a surfactant-free graphene oxide-polylactic acid (GO/PLA) nanocomposite with customizable honeycomb patterns was, for the first time, prepared via a scalable two-step solution method to achieve a power-boosted biocompatible TENG. The first step of this method involved using a suitable solvent (such as dimethylformamide) to well disperse the GO nanoparticles into PLA. Subsequently, honeycomb patterns were induced by using a mixture of chloroform and methanol as a suitable volatile solvent/nonsolvent pair for improved phase separation. The results indicated that GO nanoparticles with large surface area and abundant electron-donating groups decorated the honeycomb patterns and significantly influenced the electro-positivity and surface properties of the PLA bio-polymer. An unprecedented antagonistic TENG (A-TENG) based on the concave-honeycomb GO-PLA (hc-GO/PLA) and its corresponding convex-polydimethylsiloxane (c-PDMS) form a pair of tribo-components with antagonistic friction surfaces and generate an output power of 3.25 mW, which is 13.6 times higher than that of a flat-surface TENG (f-TENG) without GO additives. We believe that the incorporation of functional GO nanoparticles without surfactants expands the potential applications of biocompatible A-TENG in healthcare areas thanks to its boosted output performance and persisting biocompatibility.

In the room temperature environment, we have prepared COFs with controllable morphology and particle size in the aqueous phase with liquid surfactant. [Display omitted] • Appropriate co-solvents were used to the assisted preparation of COF nanomaterials. • COF nanomaterials were successfully synthesized without surfactant in water at room temperature. • The addition method of HAc catalyst had a strong influence on the size and crystallinity of COF nanospheres. • Water as solvent played an important role in size adjustment of COFs. Covalent organic frameworks (COFs) are a new class of porous materials receiving much attention due to their unique characteristics. However, COFs have been usually synthesized under harsh and complicated conditions, limiting their practical applications. We propose a surfactant-free strategy to controllably synthesize an imine-based covalent organic framework (COF) nanomaterial in water at room temperature. Introduction of tiny amounts of co-solvents not only achieves the morphology and size control of COFs but also ensures stability of COF nanomaterials in aqueous solution. Moreover, water as a solvent plays an important role in the size adjustment of COFs. The surface area of the obtained COFs was approximately 398 m2/g with a pore size distribution of about 2.8 nm. In addition, the COFs displayed a good crystallinity. [ABSTRACT FROM AUTHOR]

Summary: Direct ammonia fuel cells (DAFCs), wherein the ammonia oxidation reaction (AOR) occurs at the anode and oxygen reduction at the cathode, are a promising clean energy production system using easily liquefied ammonia because they exhibit high energy density. However, only a few catalysts are, thus far, available for the AOR because of its sluggish six‐electron‐based reaction kinetics. Pt (100) is considered an optimal catalyst for the AOR; however, the synthesis of pristine Pt (100) is difficult because it requires the use of strong capping agents for faceting particles. Moreover, the capping agents block surface active sites, thereby deaccelerating electrochemical reactions. Herein, we report a novel synthetic method (hot separation) to achieve pristine Pt (100) by precisely controlling the formation kinetics of Pt nanocubes, wherein the further treatment for surface capping agent removal is not required. Hot separation prevents particle aggregation and overgrowth through the rapid separation of the Pt nanocubes and reaction solution and preserves the Pt (100) surface. Furthermore, the characterization of the pristine surface of Pt nanocubes was conducted to compare the properties of the Pt nanocubes with those of the particles prepared from conventional methods. The Pt nanocubes showed better mass activity toward the AOR and 2.3 times higher DAFC performance than those of commercial Pt. [ABSTRACT FROM AUTHOR]

[Display omitted] • We synthesize surfactant-free Ir nanoparticles in different solvents. • We compare the performance of OER catalysts made from these colloids. • We demonstrate that high dispersion can be reached in a wide range of metal loadings. • We show that for reaching such high dispersion, the colloidal stability of the nanoparticles as well as the support in the respective solvent is key. Water electrolysis is a pivotal technology to drive the energy transition towards a system based on renewable resources. The scarce Ir is a crucial element for the synthesis of heterogeneous catalysts for the oxygen evolution reaction (OER). Carbon supported Ir oxide catalysts obtained from surfactant-free colloidal Ir nanoparticles (NPs) synthesized in alkaline methanol (MeOH), ethanol (EtOH), and ethylene glycol (EG) are investigated and compared. The comparison of independent techniques such as transition electron microscopy (TEM), small angle X-ray scattering (SAXS), and electrochemistry allows shedding light on the parameters that affect the dispersion of the active phase as well as the initial catalytic activity. The colloidal dispersions obtained are suitable to develop supported OER catalysts with little NP agglomeration on a carbon support. Due to the high dispersion of the active phase, initial catalytic activities of more than 400 A g−1 Ir are reached at 1.5 V RHE when using carbon as a model support. While the more common surfactant-free alkaline EG synthesis requires flocculation and re-dispersion leading to Ir loss, the main difference between methanol and ethanol as solvent is related to the dispersibility of the support material. The choice of the suitable monoalcohol determines the maximum achieved Ir loading on the support without detrimental particle agglomeration. This simple consideration on catalyst design can readily assist the implementation of more relevant support materials for technical applications and significantly improved catalysts. [ABSTRACT FROM AUTHOR]

Colloidal syntheses of nanoparticles (NPs) are one of the preferred approaches to prepare precious metal catalysts. Unfortunately, most colloidal syntheses developed require stabilizing agents to avoid NP agglomeration and/or control NP size and morphology. While these surfactants can bring positive features, they typically block catalytically active sites on the NP surface. As a consequence, these additives often need to be removed by energy and/or time consuming steps, at the risk of complicating the synthesis, introducing irreproducibility and negatively altering the structure and properties of the prepared catalysts. Fortunately, several surfactant-free colloidal syntheses have been reported and are being developed. This Mini Review addresses the challenges in defining a surfactant-free colloidal synthesis of NPs and survey established and emerging strategies to obtain surfactant-free colloidal precious metal NPs. A focus is given to approaches that show promising features to bridge the gap between fundamental and applied research towards industrial applications.

Emulsions have a range of applications, for example, in cosmetics, pharmaceuticals, and food. However, the surfactants used to prepare such emulsions can often be toxic to humans and the environment and also affect the oil properties of emulsions. Therefore, interest in surfactant-free emulsions has increased in recent years. One method to enhance emulsion stability without a surfactant is to use a gelling agent to increase the viscosity. Gelling agents are viscous hydrocolloids that gel when dispersed in water, even at low concentrations. In this study, we prepared six oil-in-water emulsions (oil content 20%) with different gelling agents (xanthan gum, Carbopol 981, TR-2, and Ultrez 20) and investigated the effect of the gelling agent concentration. For each sample, particle size and emulsion stability analysis were performed at high temperatures to ensure the stability of the emulsions. We observed that the emulsion prepared using TR-2 (0.25 wt%) did not aggregate at high temperatures for one month. Based on our assessment of the stability of these emulsions under various conditions, we believe that the use of gelling agents for the preparation of surfactant-free emulsions shows great promise for applications requiring long-term stable emulsions, such as cosmetics and medicine.

Purpose: The aim of this work was to formulate and characterize surfactant-free glibenclamide nanoparticles using Eudragit RLPO and polyethylene glycol as sole stabilizer. Methods: Glibenclamide nanoparticles were obtained by nanoprecipitation and evaluated in terms of drug content, encapsulation efficiency, apparent saturation solubility, drug release profile, solid state and storage stability. The influence of different stirring speed on the particle size, size distribution and zeta potential of the nanoparticles was investigated. The nanoparticle biocompatibility and permeability were analyzed in vitro on Caco-2 cell line (clone HTB-37) and its interaction with mucin was also investigated. Results: It was found that increasing the molecular weight of polyethylene glycol from 400 to 6000 decreased drug encapsulation, whereas the aqueous solubility and dissolution rate of the drug increased. Particle size of the nanoformulations, with and without polyethylene glycol, were between 140 and 460 nm. Stability studies confirmed that glibenclamide nanoparticles were stable, in terms of particle size, after 120 days at 4°C. In vitro studies indicated minimal interactions of glibenclamide nanoparticles and mucin glycoproteins suggesting favorable properties to address the intestinal mucus barrier. Cell viability studies confirmed the safety profile of these nanoparticles and showed an increased permeation through epithelial cells. Conclusion: Taking into consideration these findings, polyethylene glycol is a useful polymer for stabilizing these surfactant-free glibenclamide nanoparticles and represent a promising alternative to improve the treatment of non-insulin dependent diabetes. [ABSTRACT FROM AUTHOR]

• Introducing oil into an aqueous phase using our Nanopore system in conjunction with ultrasound gave rise to milky oil nanodroplet solutions. • Control experiments without the use of nanopores did not result in phase mixing. • This work demonstrates that our Nanopore system can generate stable nanoemulsions in the absence of a surfactant, persisting in phase separation for several days up to two weeks at room temperature and cold storage. • This work suggests that nanopores are effective in producing surfactant-free nanoemulsions, which offer a wide range of valuable applications varying from drug delivery and food engineering, to paints and pesticide development. Phase separation of heterogeneous liquids can occur in the presence of sufficient shear force between a solid interface and a liquid. We hypothesize that a continuous flow of oil through nanopores into water in combination with a given ultrasound energy can generate stable free standing oil emulsions in water in the absence of surfactants. An oil solution was pumped through a membrane with 100 nm pores at a controlled flow rate and introduced into an aqueous solution while being subjected to sonication. The resulting emulsion samples were collected at specific time intervals and characterized by dynamic light scattering and nanoparticle tracking analysis techniques. We evaluated the storage stability of the emulsions with and without surfactant at room temperature or 4 °C storage. Introducing oil into an aqueous phase using our Nanopore system in conjunction with ultrasound gave rise to surfactant-free milky oil nanodroplet solutions. Dynamic light scattering and nanoparticle tracking analysis showed that the produced surfactant-free oil nanodroplets were monodispersed in water at sizes less than 200 nm. Control experiments without the use of nanopores did not result in phase mixing. Nanoemulsions were also generated in a surfactant containing solution resulting in a similar size range of nanodroplets. This work demonstrates that our Nanopore system can generate stable nanoemulsions in the absence of a surfactant, persisting in phase separation for several days up to two weeks at room temperature and 4 °C storage. This work suggests that nanopores are effective in producing surfactant-free nanoemulsions, which offer a wide range of valuable applications varying from drug delivery and food engineering, to paints and pesticide development. [ABSTRACT FROM AUTHOR]

Biofunctional emulsion coatings of curcumin-loaded poly(ɛ-caprolactone)/polyvinyl alcohol-hydroxyapatite (Cur-loaded PCL/PVA-HA) were developed on the titanium (Ti) plates without using any surfactant. Firstly, stable oil-in-water emulsions with different water/oil (W/O) ratios (9:1, 7:1, 5:1 and 3:1) were prepared by using the uniform PVA-HA slurry as a water phase and the Cur-loaded PCL solution as an oil phase. The diameter of the oil droplets in those emulsions mostly ranged from 4 to 6 µm. Subsequently, the emulsions were formulated into coatings on Ti through a spin-coating process. The obtained emulsion coatings consisted of Cur-loaded PCL microspheres that were evenly embedded in the PVA-HA matrix, and their phase composition was identified by the FT-IR analysis. The emulsion coatings were hydrophilic and displayed a gradual increase in water contact angles with the decrease of the W/O ratio. Moreover, abundant bone-like apatite aggregates were formed on the emulsion coatings, suggesting their excellent in vitro bioactivity. In addition, the emulsion coatings exhibited a sustained drug release behavior within 2–48 h, and the release process was mainly controlled by diffusion. The present study provides a new perspective on green and facile fabrication of functional emulsion coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

Hollow microparticles are important materials, offering a larger surface area and lower density than their solid counterparts. Furthermore, their inner void space can be exploited for the encapsulation and release of guest species in a variety of applications. Herein, we present phosphazene-based silica hollow microparticles prepared via a surfactant-free sol-gel process through self-assembly of the alkoxysilyl-containing polymer in water–ethanol solution. Solely, a silane-derived polyphosphazene was used as the precursor for the microparticle formation, without additional classical silica sources. These novel hollow silica-based microparticles were prepared without surfactant, using a designed amphiphilic polyphosphazene for the particle formation made by two components, a hydrophilic unit consisting of 3-mercaptopropyl(trimethoxysilane), and a hydrophobic unit (dodecanethiol) attached to the double bonds from the poly(allylamine)phosphazene backbone via a thiol-ene photoreaction. Due to these two functionalities, a “vesicle”-like self-assembled structure was formed in the reaction medium, which could be then utilized for the microparticle preparation. The influence of NaOH during the synthesis was shown to affect the size and the wall thickness of the microparticles. This effect may enhance the possibilities to tailor such microparticles for drug delivery purposes or for future controlled release of other substances, such as drugs, fragrances, or anticorrosive pigments.

The effect of the hydrophobicity of block copolymer macro-RAFT agents on the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene was investigated. Three different copolymers, poly(dimethyl aminoethyl acrylate) (PDMAEA), poly(dimethyl aminoethyl acrylate-co-styrene)-b-(butyl acrylate) (P(DMAEA-co-St)-b-PBA) and poly(dimethyl aminoethyl acrylate-co-styrene)-b-(hexafluorobutyl acrylate) (P(DMAEA-co-St)-b-PHFBA), which had different hydrophobicity in their hydrophobic segments, were synthesized and used as the macro-RAFT agents. When P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA were used as macro-RAFT agents, the RAFT surfactant-free cationic emulsion polymerization of styrene underwent very fast. But when the PDMAEA was used as the macro-RAFT agent, no polymerization of styrene was observed. The controllability of styrene polymerization with P(DMAEA-co-St)-b-PHFBA as the RAFT agent showed much better than that with P(DMAEA-co-St)-b-PBA as the macro RAFT agent. This was ascribed to hydrophobicity difference of the hydrophobic segment between P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA macro-RAFT agents. A mechanism explanation for the controllability of emulsion polymerization was proposed. The location of the active trithiocarbonate group of the macro-RAFT agent in micelle was supposed to be a key factor affecting the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene. The hydrophobicity of the RAFT agent and nature of medium had impact on the location of the active trithiocarbonate group of the macro-RAFT agent in micelle and affected the polymerization controllability. [ABSTRACT FROM AUTHOR]

In the development of therapeutic nanoparticles (NP), there is a large gap between in vitro testing and in vivo experimentation. Despite its prominence as a model, the mouse shows severe limitations for imaging NP and the cells with which they interact. Recently, the transparent zebrafish larva, which is well suited for high-resolution live-imaging, has emerged as a powerful alternative model to investigate the in vivo behavior of NP. Poly(D,L lactic acid) (PLA) is widely accepted as a safe polymer to prepare therapeutic NP. However, to prevent aggregation, many NP require surfactants, which may have undesirable biological effects. Here, we evaluate 'safe-by-design', surfactant-free PLA-NP that were injected intravenously into zebrafish larvae. Interaction of fluorescent NPs with different cell types labelled in reporter animals could be followed in real-time at high resolution; furthermore, by encapsulating colloidal gold into the matrix of PLA-NP we could follow their fate in more detail by electron microscopy, from uptake to degradation. The rapid clearance of fluorescent PLA-NP from the circulation coincided with internalization by endothelial cells lining the whole vasculature and macrophages. After 30 min, when no NP remained in circulation, we observed that macrophages continued to internalize significant amounts of NP. More detailed video-imaging revealed a new mechanism of NP transfer where NP are transmitted along with parts of the cytoplasm from endothelial cells to macrophages. Unlabelled Image [ABSTRACT FROM AUTHOR]

• Room temperature synthesis of surfactant-free colloidal Pt nanoparticles in alkaline methanol. • Faster kinetics of formation within seconds in water-containing solvent. • Nanoparticles so obtained are suitable electrocatalysts. A fast, simple, instrument-free room temperature synthesis of stable electroactive surfactant-free colloidal Pt nanoparticles in alkaline methanol and methanol-water mixtures is presented. Pair distribution function (PDF) analysis suggests that methoxy substitution of chloride ligands from H 2 PtCl 6 occurs in methanol. X-ray absorption spectroscopy (XAS) studies and UV–vis measurements show that solutions of H 2 PtCl 6 in methanol age and are reduced to Pt(II) species over time. These species are ideal precursors to significantly reduce the induction period typically observed in colloidal Pt nanoparticle syntheses as well as the temperature needed to form nanoparticles. The room temperature synthesis presented here allows designing simple in situ studies of the nanoparticle formation. In situ infra-red spectroscopy gives insight into the formation and stabilization mechanism of surfactant-free nanoparticles by CO surface groups. Finally, the surfactant-free nanoparticles ca. 2–3 nm in diameter obtained are shown to be readily active electrocatalysts e.g. for methanol oxidation. The synthesis approach presented bears several advantages to design new studies and new syntheses of surfactant-free colloidal nanomaterials. [ABSTRACT FROM AUTHOR]

Understanding the formation of nanoparticles (NPs) is key to develop materials by sustainable routes. The Co4CatTM process is a new synthesis of precious metal NPs in alkaline mono‐alcohols well‐suited to develop active nanocatalysts. The synthesis is 'facile', surfactant‐free and performed under mild conditions like low temperature. The reducing properties of the solvent are here shown to strongly influence the formation of Pt NPs. Based on the in situ formation of CO adsorbed on the NP surface by solvent oxidation, a model is proposed that accounts for the different growth and stabilization mechanisms as well as re‐dispersion properties of the surfactant‐free NPs in different solvents. Using in situ and ex situ characterizations, it is established that in methanol, a slow nucleation with a limited NP growth is achieved. In ethanol, a fast nucleation followed by continuous and pronounced particle sintering occurs. [ABSTRACT FROM AUTHOR]

Nanoparticulate (NP) films and organic photovoltaic devices have been fabricated from poly(3-hexylthiophene):phenyl C61 butyric acid methyl ester (P3HT:PC61BM) NP aqueous dispersions prepared by the precipitation method. The NP inks were stable for more than 4 days, and nanoparticle organic photovoltaic (NP-OPV) devices with efficiency (η) of 1% were fabricated. Detailed analysis of the morphology and performance of the precipitated NP-OPV devices indicated that an optimal blend is responsible for the photocurrent and efficiency observed. These results were confirmed by grazing-incidence x-ray diffraction (GIXRD) analysis, which revealed that the precipitated NPs were resistant to thermal phase segregation, allowing thermal conditioning of the NP films. These results show that precipitated NPs provide a pathway to thermally stable NP-OPV devices with higher photocurrents and efficiencies, approaching those of optimal bulk heterojunction (BHJ) OPV devices. [ABSTRACT FROM AUTHOR]

Despite the widespread use of surfactants, there are known issues such as allergic reactions and formulation complications in their use as emulsion stabilizers. In this study, stabilizer-free water-in-oil (W/O) emulsions containing water, phytantriol, and almond oil were prepared by an ultra-turrax homogenizer, a standard laboratory equipment, and a high specialized high-shear device. Parameters such as mixing time, stirring rate, composition, order of addition of phases, and temperature were investigated to systematically optimize the preparation of the formulations through evaluating their accelerated physical stability by a centrifugal sedimentation technique. The liquid crystalline structure of the continuous phase was studied by small-angle X-ray scattering indicating a reverse hexagonal phase (H 2). Microscopy images showed the emulsions prepared via high-shear method had smaller water droplets with more uniform shape and better dispersion as confirmed by Fourier-transform infrared–attenuated total reflection spectroscopy. Rheology studies showed a larger yield stress value for emulsions with higher content of phytantriol. Our results indicated that emulsions prepared by the high-shear device with higher amount of phytantriol were the most stable formulations. Applying the correct variables in the preparation of the stabilizer-free emulsions using ultra-turrax homogenizer, one could obtain similarly stable emulsions lacking the uniformity of the droplets. [ABSTRACT FROM AUTHOR]

With the rapid development of nanotechnology and catalysis science, numerous enzyme-mimicking nanomaterials have been rationally designed as the substitutes for natural enzymes. Herein, the Pt-loaded hollow mesoporous carbon nanospheres (Pt-HMCNs) were proposed as the peroxidase mimic for the first time. The monodispersed HMCNs with huge hollow cavity and mesoporous carbon skeleton were first synthesized via high-temperature carbonization and NaOH etching of core–shell structured SiO2@RF/SiO2 (RF = resorcinol–formaldehyde resin) nanospheres, which were prepared through a simple surfactant-free strategy in a one-pot system only containing three main raw chemicals as tetraethyl orthosilicate, resorcinol, and formaldehyde. And then the Pt-HMCNs were obtained through surface graft of −NH2 groups and loading of as-synthesized ultrasmall Pt nanoparticles (NPs) in size of 1–3 nm on the HMCNs. The prepared Pt-HMCNs nanocomposites exhibited superior peroxidase-like catalytic activity toward the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) substrate, which owned stronger affinity to H2O2 and TMB as substrates than the natural enzyme (horseradish peroxidase). The outstanding peroxidase-mimic performance of the Pt-HMCNs is due to the unique hollow mesoporous structure as well as the interfacial effect between Pt NPs and carbon skeleton. A simple and general colorimetric approach was established to accurately detect ascorbic acid (AA) and glucose, and their detection limits were calculated to be 3.29 and 35.4 μM, respectively. Besides, wide linear range and high selectivity against interfering substances were also achieved in this assay during AA and glucose detection based on the Pt-HMCNs catalyst. The colorimetric method built on Pt-HMCNs in this work could be applied to biomedicine, food science, environment monitoring, and other fields for accurately detecting ascorbic acid, glucose, and other important substances in some complex systems. [ABSTRACT FROM AUTHOR]

N,N-Dimethylcyclohexylamine—a switchable-hydrophilicity solvent, ethanol and water could be used to prepare a CO2-switchable surfactant-free microemulsion (SFME). The ternary phase diagram was used to investigate the phase behavior of SFME. The electrical conductivity measurement, UV-visible spectra were used to investigate the microstructure and structural transition of SFME. Dynamic light scattering could be used to measure the diameter of SFME. The above results indicated that the microemulsion existed three microstructures: water-in-DMCHA (W/O), bicontinuous, and DMCHA-in-water (O/W). The variation tendency of electrical conductivity of SFME while CO2 and N2 alternately passing through was determinate, which proved SFME has excellent CO2-switchable performance. Residual oil rate that using the W/O SFME to clean oily drill cuttings is very low, and oil from cuttings can be recycled, which shows CO2-switchable SFME has much significance in washing oily drill cuttings. [ABSTRACT FROM AUTHOR]

Two copolymer microspheres, poly(styrene-N,N′-methylenebis(2-propenamide)-acrylic acid) (PS-MBA-AA) and poly(styrene-N,N′-methylenebis(2-propenamide)-methacrylic acid) (PS-MBA-MAA), were synthesized through a surfactant-free one-pot copolymerization method, rendering them easily prepared. Through the utilization of scanning electron microscopy (SEM), laser particle size analysis, Fourier transform infrared spectroscopy (FTIR), BET adsorption-desorption isotherms, and energy dispersive spectrometry (EDS), the structures of PS-MBA-AA and PS-MBA-MAA were meticulously examined. These analyses provided substantial evidence that the copolymer microspheres possess a relatively uniformity in terms of both particle size and composition. The copolymer microspheres, PS-MBA-AA and PS-MBA-MAA, demonstrate remarkable efficiency in the rapid adsorption of Cu2+, Pb2+, and Cd2+. Notably, they possess the ability to achieve over 80% of their equilibrium adsorption capacity within a mere 10 min. It is worth noting that both types of copolymers exhibit superior adsorption efficacy and anti-coexisting ion interference, particularly in relation to Pb2+ among the three of heavy metal ions. [Display omitted] [ABSTRACT FROM AUTHOR]

Phase separation control is an important factor to prepare a porous monolith by an aqueous sol–gel reaction. Here, we report a surfactant-free synthesis method to obtain hydrophobic polymethylsilsesquioxane aerogels by copolymerizing a cationic-functionalized alkoxysilane N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride. The resultant materials have low-density, high visible-light transmittance, and high thermal insulating equivalent to those of prepared under the presence of surfactant.

Fluoridated hydroxyapatite (FHA) [Ca 10 (PO 4) 6 F x (OH) 2−x , x = 0–2] is believed to be a promising calcium phosphate (CaP) to replace pure hydroxyapatite (HA) for next-generation implants, owing to its better biocompatibility, higher antibacterial activity, and lower solubility. Notably, the shape and size of the CaP crystals play key roles in their performance and can influence their applications. One-dimensional (1D) FHA nanorods are important CaP materials which have been widely used in regenerative medicine applications such as restorative dentistry. Unfortunately, the traditional synthesis methods for FHA nanorods either employ surfactants or take a relatively long time. In this study, we aimed to propose a facile synthesis route to fabricate FHA nanorods without any surfactants using an electrochemical deposition method for the first time. This study focused on preparing FHA nanorods without the assistance of any surfactant, unlike the traditional synthesis methods, to avoid chemical impurities. FHA nanorods with lengths of 124–2606 nm, diameters of 28–211 nm, and aspect ratios of 4.4–21.8 were synthesized using the electrochemical method, followed by a heat treatment. For the as-synthesized FHA nanorods, the Ca/P ratio was 1.60 and the atomic concentration of F was 2.06 at.%. An ultrastructure examination revealed that each FHA nanorod possessed long-range order, good crystallinity, and a defect-free lattice with a certain crystallographic plane orientation along the whole rod. In short, we propose a novel, surfactant-free, cost-saving, and more efficient route to synthesize FHA nanorods which can be widely applied in multiple biomedical applications, including drug delivery, bone repair, and restorative dentistry. [ABSTRACT FROM AUTHOR]

Rapid and scalable preparation of polymer-based magnetic microcapsules (MMCs) without employing any templates and surfactants is still a challenge. Herein, we present a one-step template/surfactant-free strategy for fast and large-scale fabrication of poly(vinyl alcohol) (PVA)-based MMCs. The MMCs are formed from simultaneous creation of magnetic Fe 3 O 4 nanoparticles and crosslinking of PVA chains, which is achieved by simple addition of ammonia solution into the preformed water-in-oil (W/O) emulsion comprising castor oil, aqueous mixture of PVA and iron salts. The size and shell thickness of MMCs could be readily controlled by fine tuning the process parameters. Furthermore, this approach allows for incorporation of additional functional nanoparticles into the PVA shell of MMCs, as demonstrated by the fabrication of Pt nanoparticles decorated MMCs (Pt-MMCs) in this study. The Pt-MMCs displayed favorable catalytic activity for reduction of aromatic nitro compounds (e.g., 4-nitrophenol and 4-nitroaniline), and could be conveniently recycled using magnet and reused for > ten times without obvious decline of catalytic activity. This work thus opens a new pathway for facile fabrication of property-tailored MMCs to meet the requirements of various applications. [ABSTRACT FROM AUTHOR]

Gold nanoparticle is an important photothermal conversion material in photothermal imaging and photothermal therapy research. There are diverse gold nanoparticles, including gold nanospheres, gold nanorods, gold nanocages, gold nanoshells and gold nanostars. Among them, gold nanostar (AuNS) possesses more excellent prospective imaging contrast agent for cancer diagnosis than other shapes of gold nanoparticles because of its larger photon interception area and cross section as well as scattering characteristics. The properties of AuNS are susceptible to synthetic methods and conditions. In this study, we presented surfactant-free methods to synthesize AuNS, discussed the relationship of AuNS characterization with the synthetic conditions and tested its photothermal effect. The results indicated that length and number of branches in AuNSs were the main factor for absorption wavelength in photothermal conversion, and the AuNSs could be more precisely controlled by changing the synthesis conditions. [ABSTRACT FROM AUTHOR]

Formic acid oxidation is usually catalyzed on PdPt bimetallic catalysts, which are synthesized by co-reduction of noble metal precursors in the presence of high molecular capping agents. In this work, surfactant-free Pd x Pt y /C catalysts are synthesized by H 2 reduction in ethylene glycol assisted with ultrasonication vibration at room temperature. Nanoparticle agglomeration in the course of preparation has been sufficiently curbed by strong mechanical ultrasonication instead of traditionally-employed surfactants. As a result, "clean" surfactant-free Pd x Pt y /C catalysts necessitate only simple washing before collection. The catalysts are characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The compositionally optimized Pd 100 Pt 1 /C catalyst registers a mass activity of 3171 A g−1 (Pt + Pd) for formic acid oxidation in 0.5 M H 2 SO 4 +0.5 M HCOOH, which lists one of the best results reported so far and surpasses that of a commercial Pd/C by 5.6 times. Stability of the catalysts is investigated by cyclic voltammetric as well as chronoamperometric evaluations. This work offers a convenient and environmentally benign room-temperature route to synthesize highly active and stable catalysts for formic acid oxidation. Surfactant-free Pd x Pt y /C catalysts are synthesized by H 2 reduction in ethylene glycol assisted with ultrasonication vibration at room temperature. Nanoparticle agglomeration has been sufficiently curbed by strong mechanical ultrasonication instead of traditionally-employed surfactants. Image 1 • "Clean" Pd x Pt y /C are synthesized by H 2 reduction assisted with ultrasonication. • Optimized Pd 100 Pt 1 /C catalyst registers a mass activity of 3171 A g−1 for FAO. • Cavitation and reduced skin friction by ultrasound contributed to uniform particles. • Mass activity ranks one of the best results in literature. [ABSTRACT FROM AUTHOR]

Highlights • Ultrasonic nano-emulsification has thoroughly been reviewed. • Low and high energy nanoemulsion preparation methods, with comprehensive comparison among ultrasonic nano-emulsification and other methods are discussed. • Analyzes data for surfactant-free nanoemulsions and also tandem ultrasonic nano-emulsification are included. Abstract The emulsions with nano-sized dispersed phase is called nanoemulsions having a wide variety of applications ranging from food, dairy, pharmaceutics to paint and oil industries. As one of the high energy consumer methods, ultrasonic emulsification (UE) are being utilized in many processes providing unique benefits and advantages. In the present review, ultrasonic nano-emulsification is critically reviewed and assessed by focusing on the main parameters such pre-emulsion processes, multi-frequency or multi-step irradiations and also surfactant-free parameters. Furthermore, categorizing aposematic data of experimental researches such as frequency, irradiation power and time, oil phase and surfactant concentration and also droplet size and stability duration are analyzed and conceded in tables being beneficial to indicate uncovered fields. It is believed that the UE with optimized parameters and stimulated conditions is a developing method with various advantages. [ABSTRACT FROM AUTHOR]

Abstract Palladium nanorods (PdNRs) into mesoporous channels of SBA-15 nanocatalyst (PdNRs/SBA-15) were synthesized by a green and surfactant-free ultrasonic method without any surfactants and complex chemical modification and chemical method in absence of ultrasound, respectively. The PdNRs/SBA-15 catalysts were characterized by XRD, TEM, XPS, N 2 absorption-desorption and FT-IR analysis. The results showed that PdNRs with 15.96 ± 3.89 nm long and 5.69 nm wide were highly dispersed into mesoporous channels exploiting the confine effect of SBA-15 pore channel, while reunited PdNPs were distributed on the outside surface of SBA-15 in PdNPS/SBA-15 prepared by chemical method. The in-situ ultrasonic reduction of PdNRs/SBA-15 by the reductive radical (induced by ultrasonic process) was good for higher dispersion of Pd species and the formation of Pd species inside the mesoporous channel of SBA-15 without any structure-directing agents or surfactants. The yield of Suzuki coupling reaction between 4-bromotoluene and phenylboronic acid catalyzed by PdNRs (5)/SBA-15 reached 96.4%, which was much higher than that of PdNPs(5)/SBA-15 prepared without ultrasound (76.3%). PdNRs (5)/SBA-15 could be reused up to five times without a significant activity loss due to the strong chemical interaction and the unblocked channel. Graphical abstract Image 1 Highlights • Providing a green and facile way to prepare supported Pd nanocatalysts. • Introduction of Pd2+ in pore channel by roasting instead of chemical modification. • In-situ ultrasonic reduction of Pd2+ fosters uniform dispersion of Pd in the pore. • PdNRs (5)/SBA-15 shows enhanced catalytic and cycle performance for Suzuki reaction. [ABSTRACT FROM AUTHOR]

Fabrication of NiP-SiC nanocomposite coatings through the electroless deposition in a commercial electrolyte containing the low concentrations of SiC nanoparticles on carbon steel substrate was studied in this work. The confirmation of co-deposition of Ni matrix and SiC nanoparticles was investigated by evaluating the effect on morphology, crystal structure, and corrosion behavior of the heat-treated coatings which were investigated by scanning electron microscope, x-ray diffraction (XRD), and electrochemical measurements, respectively. The XRD results revealed that the heat-treated NiP and NiP-SiC coatings consisted of Ni and Ni _3 P phases, which the calculated faction of Ni _3 P phase for NiP and NiP-SiC samples is 58.2 and 62.2%, respectively. The corrosion resistance of nanocomposite samples is higher than that of pure NiP sample (9 to 76% corrosion inhibition efficiency. The tribological behavior of the coatings was characterized by microhardness measurement and ‘pin on disk’ wear test. By co-deposition of SiC nanoparticles, the hardness of heat-treated NiP is significantly increased (near 25%) and the wear loss is reduced (near 48%), especially at high sliding distance during wear test. The sample prepared through the surfactant-free electroless bath containing the 1 g l ^−1 SiC nanoparticle showed the best corrosion as well as wear resistance.

Inspired by the redox reactions in the preparation of the iron gall ink that has been used in Europe since the Middle Ages, we developed a technology for forming the oil-in-water emulsions, without any surfactants and emulsifiers, by homogenizing a mixture of tannic acid, gallic acid, Fe(D-gluconate)2, and natural oil, which are all approved as cosmetic ingredients. Various plant-derived oils, such as argan oil, olive oil, sunflower oil, grape seed oil, hemp seed oil, peppermint oil, rosemary oil, and ylang-ylang oil, were used as an oil phase for the emulsion formation, and all the fabricated emulsions exhibited the capability of black hair-dyeing. This surfactant-free emulsion technology for combining the hair-dyeing capability of Fe3+–tannin complex with the hair-fortifying property of natural oil would have great impact on the hair-cosmetic industry.