•Vinyl–SiO2 was synthesized from tetraethyl orthosilicate and vinyltriethoxysilane.•Vinyl–SiO2 was modified with PMHS and APEG via two-step hydrosilylation reactions.•The resultant hybrid nanoparticles possessed tunable wettability.•The modified SiO2 showed uniform monodispersity both in ethanol and toluene.•The modified SiO2 with moderate wettability could emulsify silicone oil/water system.In this paper, vinyl-capped silica nanoparticles (V–SiO2) were first synthesized from tetraethyl orthosilicate (TEOS) and vinyltriethoxysilane (VTEOS). Then the V–SiO2 nanoparticles were modified with poly(methylhydrosiloxane) (PMHS) and allyl-poly(ethylene glycol) (APEG) to form core-shell hybrid particles V–SiO2/PMHS/APEG, which showed tunable wettability as well as uniform monodispersity in ethanol and toluene. Particularly, V–SiO2/PMHS/APEG samples with moderate wettability could be served as emulsion stabilizer for silicone oil–water system. The modified particles were characterized by static contact angle (CA), Fourier transform infrared (FT-IR) spectroscopy, FT–Raman spectroscopy, 29Si CP MAS NMR, thermal analysis (TGA), transmission electron microscopy (TEM) and particle size distribution. FT-IR, FT–Raman and 29Si CP MAS NMR demonstrated that PMHS together with APEG was chemically anchored to the surface of nano-SiO2. Deduced from static contact angle, strong hydrophobicity (CA = 157.76°) could be achieved for V–SiO2/PMHS particles (m(PMHS):m(V–SiO2) = 1:1), while V–SiO2/PMHS/APEG samples exhibited moderate wettability (CA = 89.20°) when the mass ratio of V–SiO2, PMHS and APEG was conducted at 1:1:6.0. Thermal analysis (TGA) showed that the grafting yield of PMHS and APEG was 5.76 × 10−5 and 6.13 × 10−4 mol/g, respectively. V–SiO2/PMHS/APEG samples displayed superior monodispersity in both ethanol and toluene, and the mean diameter was 245.5 nm, revealed from particle size distribution. Furthermore, digital photos, optical micrographs and emulsion drop size distribution demonstrated that silicone oil/water emulsions were successfully stabled by the core-shell hybrid particles V–SiO2/PMHS/APEG.

•The addition of PMHS made it possible to form emulsions under alkaline conditions.•A phase inversion from o/w to w/o can be observed as the aqueous pH grows.•The particles were chemically modified by PMHS under alkaline conditions.•Emulsions stabilized by particles and PMHS can be stored for 3 months.•Pickering emulsions and modified particles were prepared by one pot method.Pickering emulsions prepared from cyclohexanone and silica sol with equal volumes have been investigated in this article. The aggregation of particles in the sols at different pHs was mainly attributed to the weak electrostatic repulsion in accordance to the classical DLVO theory. The emulsions stabilized solely by sol particles were unstable to creaming and coalescence after a period of storage, and phase separations were observed at aqueous pH > 7. In the presence of PMHS, the emulsion stability increased dramatically, and droplets began to form under alkaline conditions. At pH = 11, emulsions stabilized by PMHS and particles inverted from o/w to w/o. The causality was investigated by using Fourier transform infrared (FT-IR) spectroscopy, thermal analysis (TGA and DTG) and 29Si CP MAS NMR to characterize the surface nature of particles around the dispersed droplets. It was summarized that the acid conditions were just contributed to the particle aggregation, and no reaction between PMHS and particles was observed. However, alkaline conditions were tested to be responsible for the chemical grafting of PMHS onto particle surfaces, which increased the hydrophobicity of particles and inverted the type of emulsions from o/w to w/o. As a result, stable emulsions and modified particles were prepared simultaneously by one pot method through ball milling.

•Transparent superhydrophobic films were prepared from silica aerogels deposition.•The surface energy of as-prepared films in our work is basically constant.•Wettability and transparency of films are determined by aerogel microstructure.•The films could switch from superhydrophobic to superhydrophilic by heating.•The moisture resistance of films can be improved further by CTMS treatment.Highly transparent superhydrophobic silica aerogel films with high water contact angle (>160°) and low sliding angle (<5°) were prepared by using methyltrimethoxysilane (MTMS) as precursor based on a simple sol–gel process. The influences of different solvent amount on the superhydrophobicity, transparency, microstructure, N2 adsorption–desorption behavior and pore size distribution of as-prepared films were discussed herein to get the film with optimum performance. The optimum film exhibits superhydrophobicity (CA, 161° and SA, 4°), high transparency (transmittance closes to 90%) and good thermal stability (up to 500 °C). Note that the optimum film directly from sol–gel process exhibits poor moisture resistance. The low density, high volume-fraction porosity structure and methyl groups on the surface are the cause of superhydrophobicity of the film. Low density and high volume-fraction porosity structure are also responsible for the thermal stability of the as-prepared film, and the poor moisture resistance is ascribed to the untreated hydroxyl groups on the surface of the film. The moisture resistance of film can be improved by further treatment with cetyltrimethoxysilane (CTMS). The film switches from superhydrophobic (161°) to superhydrophilic (0°) after heat-treated at 600 °C.

Transparent superhydrophobic nanocoating, possessing a sub-100 nm roughness, a high water contact angle (>160°) and a low sliding angle (<5°), has been prepared by a simple sol–gel dip-coating method. The desired hierarchical sub-100 nm roughness, which renders the nanocoating transparency, was created by using 3-aminopropyltriethoxylsilane (APTEOS) as aggregated agent. Cetyltrimethoxylsilane (CTMS) was adopted as modifying agent subsequently to give the nanocoating superhydrophobicity. The influence of experiment parameters on the transparency and superhydrophobicity of as-prepared nanocoating were investigated herein to get the optimum preparing conditions. The obtained nanocoating before and after modification were characterized and confirmed by various technologies including Fourier transform infrared (FT-IR) spectroscopy, 29Si CP (cross-polarization) MAS NMR, X-ray photoelectron spectroscopy (XPS), thermal analysis, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The as-prepared transparent superhydrophobic nanocoating exhibits a good moisture resistance, and it could switch from superhydrophobic (>160°) to superhydrophilic (0°) after heat-treating at a temperature higher than 500 °C.Transparent superhydrophobic nanocoating, possessing a good moisture resistance, had been developed by a simple sol–gel dip-coating method. 3-Aminopropyltriethoxylsilane (APTEOS) was adopted as aggregated agent to give the nanocoating transparency, and cetyltrimethoxylsilane (CTMS) was used as modifying agent to render the nanocoating superhydrophobicity.Highlights► Transparent superhydrophobic nanocoating was prepared by a simple sol–gel method. ► Desired sub-100 nm roughness was created by adding 3-aminopropyltriethoxylsilane. ► The prepared nanocoating possesses a good moisture resistance. ► The nanocoating could switch from superhydrophobic to superhydrophilic by heating.

Vinyltriethoxysilane (VTEOS) has been used as capping and size tuning agent to prepare monodisperse core–shell silica hybrid spheres. When VTEOS was used, the relative standard deviation below 3% for silica hybrid spheres can be produced by changing the concentration of VTEOS and the ammonia catalyst. The obtained hybrid particles were characterized and confirmed by various technologies including Fourier transform infrared (FT-IR) spectroscopy, FT-Raman spectroscopy, 29Si CP (cross-polarization) MAS NMR, thermal analysis, particle size distribution, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FT-IR, FT-Raman, 29Si CP MAS NMR spectra and thermal analysis confirm the existence of vinyl groups on hybrid particles. Particle size distribution, FE-SEM and TEM reveal the uniformity in size/shape and the core–shell structure of hybrid particles. The influence of experiment parameters on the resulting particles, the capping and size tuning actions of other silane coupling agents (SCAs) were investigated herein as well.Graphical abstractHighlights► Monodisperse core–shell silica hybrid spheres were prepared by one-pot process. ► Relative standard deviation below 3% for silica hybrid spheres can be produced. ► Vinyltriethoxysilane was used as capping and size tuning agent of particles.