A facile and low-cost preparation of durable amphiphobic coatings with fluoride–silica@poly(methacrylic acid) hybrid nanocomposites

Poor robustness, high cost and complicated preparation are the main barriers to the large-scale industrial application of amphiphobic coatings. A facile and low-cost method to fabricate durable amphiphobic coatings is reported in this work. The coatings were composed of top and bottom paints. The top paint was prepared by the F–Si@PMAA hybrid nanocomposites dispersion. The hybrid nanocomposites with dual structure were prepared via the co-condensation reaction of tetraethoxysilane (TEOS) and 1H,1H,2H,2H-Perfluorodecyl triethoxysilane (HDFTES) on the surface of the presynthesized PMAA nanoparticles in ethanol dispersion. The bottom one was a type of inexpensive car refinishing paint. The resulting coatings could be sprayed onto different substrates. All the coated substrates exhibited good amphiphobicity with superhydrophobicity with the water contact angle greater than 150°, water roll-off angle less than 4°, and high oleophobicity with the oil contact angle greater than 130°. Moreover, all of the prepared coatings exhibited great robustness after water jetting, sand abrasion, and knife scratching. This method can be an effective strategy for fabricating amphiphobic surfaces for practical industrial applications.     

Surface hydrophobicity: effect of alkyl chain length and network homogeneity

Understanding the nature of hydrophobicity has fundamental importance in environmental applications.Using spherical silica nanoparticles(diameter=369±7 nm)as the model material,the current study investigates the relationship between the alkyl chain network and hydrophobicity.Two alkyl silanes with different chain length(triethoxymethylsilane(C1)vs.trimethoxy(octyl)silane(C8))were utilised separately for the functionalisation of the nanoparticles.Water contact angle and inverse gas chromatography results show that the alkyl chain length is essential for controlling hydrophobicity,as the octyl-functionalised nanoparticles were highly hydrophobic(water contact angle=150.6°±6.6°),whereas the methyl-functionalised nanoparticles were hydrophilic(i.e.,water contact angle=0°,similar to the pristine nanoparticles).The homogeneity of the octyl-chain network also has a significant effect on hydrophobicity,as the water contact angle was reduced significantly from 148.4°±3.5°to 30.5°±1.0°with a methyl-/octyl-silane mixture(ratio=160:40μL·g^–1 nanoparticles).     

Superhydrophilic coatings with enhanced transmittance fabricated from solid and mesoporous silica nanoparticles

Superhydrophilic coatings with high transmittance were fabricated from solid and mesoporous silica nanoparticles (NPs) via layer-by-layer assembly followed by calcination. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 96.1%, while that of the glass substrate was 91%. The time for a droplet to spread flat (water contact angle lower than 5°) is <1?s. Scanning and transmission electron microscopies were used to observe the morphology and structure of both NPs and coating surfaces. Transmission spectra and their changes after calcination were characterized by UV–vis spectrophotometry. The surface wettability was studied using a contact angle/interface system.     

Preparation and dispersibility of poly(L‐lactide)‐grafted silica nanoparticle

To improve dispersibility of silica nanoparticle in organic solvents, the grafting of poly(L ‐lactide) (PLLA) onto silica nanoparticle surface by ring‐opening polymerization of L‐lactide (LA) was investigated in the presence of an amidine base catalyst. The ring‐opening polymerization of LA successfully initiated in the presence of silica having amino groups (silica‐NH₂) and an amidine base catalyst to give PLLA‐grafted silica, but not in the presence of untreated silica (silica‐OH). In the absence of the amidine base catalyst no ring‐opening polymerization of LA even in the presence of silica‐NH₂ and no grafting of PLLA onto silica were observed. It became apparent that the amidine base catalyst acts as an effective catalyst for the ring‐opening graft polymerization of LA from the surface of silica‐NH₂. In addition, it was found that the percentage of PLLA grafting onto silica could be controlled according to the reaction conditions. The average particle size of PLLA‐grafted silica was smaller than that of silica‐NH₂. Therefore, it was considered that the aggregation structure of silica nanoparticles was considerably destroyed by grafting of PLLA onto the surface. The PLLA‐grafted silica gave a stable dispersion in polar solvents, which are good solvents for PLLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Carbon dioxide‐in‐water foams stabilized with nanoparticles and surfactant acting in synergy

Synergistic interactions at the interface of nanoparticles (bare colloidal silica) and surfactant (caprylamidopropyl betaine) led to the generation of viscous and stable CO₂‐in‐water (C/W) foams with fine texture at 19.4 MPa and 50°C. Interestingly, neither species generated C/W foams alone. The surfactant became cationic in the presence of CO₂ and adsorbed on the hydrophilic silica nanoparticle surfaces resulting in an increase in the carbon dioxide/water/nanoparticle contact angle. The surfactant also adsorbed at the CO₂–water interface, reducing interfacial tension to allow formation of finer bubbles. The foams were generated in a beadpack and characterized by apparent viscosity measurements both in the beadpack and in a capillary tube viscometer. In addition, the macroscopic foam stability was observed visually. The foam texture and viscosity were tunable by controlling the aqueous phase composition. Foam stability is discussed in terms of lamella drainage, disjoining pressure, interfacial viscosity, and hole formation. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3490–3501, 2013     

Facile preparation of superhydrophobic polyester surfaces with fluoropolymer/SiO2 nanocomposites based on vinyl nanosilica hydrosols

A facile method to prepare superhydrophobic fluoropolymer/SiO₂ nanocomposites coating on polyester (PET) fabrics was presented. The vinyl nanosilica (V? SiO₂) hydrosols were prepared via one‐step water‐based sol‐gel reaction with vinyl trimethoxy silane as the precursors in the presence of the base catalyst and composite surfactant. Based on the V? SiO₂ hydrosol, a fluorinated acrylic polymer/silica (FAP/SiO₂) nanocomposite was prepared by emulsion polymerization. The FAP/SiO₂ nanocomposites were coated onto the polyester fabrics by one‐step process to achieve superhydrophobic surfaces. The results showed that silica nanoparticles were successfully incorporated into the FAP/SiO₂ nanocomposites, and a specific surface topography and a low surface free energy were simultaneously introduced onto PET fibers. The prepared PET fabric showed excellent superhydrophobicity with a water contact angle of 151.5° for a 5 μL water droplet and a water shedding angle of 12° for a 15 μL. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40340.     

四氯化硅液相鼓泡法制备纳米白炭黑工艺研究

以多晶硅副产物四氯化硅为原料,氨水为中和剂,十二烷基苯磺酸钠为改性剂,在水-醇-氨体系中利用液相鼓泡法制备纳米白炭黑,并采用IR、XRD、SEM、TEM对纳米白炭黑晶体结构、形貌、分散性及粒径进行表征。研究了醇水比、氨水用量、分散剂种类及用量、双氧水加入量等因素对纳米白炭黑分散性及粒径的影响。纳米白炭黑最佳制备工艺条件：体系总体积为70 mL,V（水）∶V（醇）∶V（氨）=38∶15∶12,六偏磷酸钠加入量为1.5%（质量分数）,双氧水用量为5 mL。IR、XRD表征结果表明产品为无定形二氧化硅;SEM、TEM表征结果表明纳米白炭黑粒径约100 nm且分散较好。     

室温固相法制备纳米γ-Fe_2O_3过程中形貌影响研究

采用室温固相法,通过2种形式分别合成了纳米γ-Fe2O3的前驱体FeC2O4.2H2O,并对其煅烧过程中不同温度下所得到的γ-Fe2O3的形貌影响进行了研究。以FeSO4.7H2O和H2C2O4·2H2O为原料,先得到了前驱体FeC2O4.2H2O,然后分别在200℃、300℃、400℃、500℃和600℃下煅烧前驱体,经X射线衍射(XRD)、透射电镜(TEM)测试手段的分析,结果表明:室温固相法合成纳米γ-Fe2O3操作简单、成本低、无污染。对前驱体球磨可以得到尺寸小分散性好的纳米γ-Fe2O3颗粒。     

Fabrication of inorganic/polymer nanocomposite membranes containing very high silica content via in situ surface grafting reaction and reactive dispersion of silica nanoparticles: Proton conduction,water uptake,and oxidative stability

In this study, we present a new fabrication process for proton exchange membranes based on inorganic/organic nanocomposite using in situ surface grafting reaction and reactive dispersion of silica nanoparticles in the presence of reactive dispersant, urethane acrylate nonionomer (UAN). Through in situ surface grafting reaction of silica nanoparticles, urethane acrylates were chemically introduced on the surface of silica nanoparticles, which were dispersed in DMSO solutions containing UAN and sodium styrene sulfonate (NaSS). After urethane linkage and copolymerization of NaSS, UAN and urethane acrylate moieties of silica nanoparticles, the solutions were converted to silica nanoparticle‐dispersed proton exchange membranes where silica particles were chemically connected with organic polymer chains. 5.89–29.45 wt % of silica nanoparticles could be dispersed and incorporated in polymer membranes, which were confirmed by transmittance electron microscopy (TEM) measurement. On varying weight % of silica nanoparticles dispersed within the membranes, water uptake and oxidative stability of nanocomposite membranes were largely changed, but membranes showed almost the same proton conductivity (greater than 10⁻² S cm⁻¹). At 5.89 wt % of silica nanoparticles, nanocomposite membranes showed the lowest water uptake and excellent oxidative stability compared to the sulfonated polyimide membranes fabricated by us. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

High stability superhydrophobic glass-ceramic surface with micro–nano hierarchical structure

Inspired by the surface structure of lotus leaves, micro–nano hierarchical surface structures have been widely used for designing superhydrophobic surfaces. However, the conventionally designed superhydrophobic surface structures are fragile. In this study, a layer of micron-sized mullite whiskers was grown using molten salt on the surface of BaAl₂Si₂O₈ (BAS) glass ceramics. Subsquently, SiO₂ nanoparticles modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane were sprayed onto the whisker layer to form a superhydrophobic surface. The nanoparticles exhibit superhydrophobicity, which is protected by the whisker layer containing pores and bulges. This prohibits direct contact between the nanoparticles and external objects. Contact and rolling angle tests indicated that the surface contact angle of the micro–nano hierarchical structure is 158° and the rolling angle is less than 10°. The stability of the superhydrophobic surface was tested through ultraviolet light, long-time immersion in solutions with various pH values, water scouring, and sandpaper abrasion. The results showed that the contact angle is greater than 150°. This study is expected to provide a simple and effective method for fabricating superhydrophobic surfaces on ceramics on a large scale.     

Influence of the Polyvinyl Pyrrolidone Concentration on Particle Size and Dispersion of ZnS Nanoparticles Synthesized by Microwave Irradiation

Zinc sulfide semiconductor nanoparticles were synthesized in an aqueous solution of polyvinyl pyrrolidone via a simple microwave irradiation method. The effect of the polymer concentration and the type of sulfur source on the particle size and dispersion of the final ZnS nanoparticle product was carefully examined. Microwave heating generally occurs by two main mechanisms: dipolar polarization of water and ionic conduction of precursors. The introduction of the polymer affects the heating rate by restriction of the rotational motion of dipole molecules and immobilization of ions. Consequently, our results show that the presence of the polymer strongly affects the nucleation and growth rates of the ZnS nanoparticles and therefore determines the average particle size and the dispersion. Moreover, we found that PVP adsorbed on the surface of the ZnS nanoparticles by interaction of the C–N and C=O with the nanoparticle’s surface, thereby affording protection from agglomeration by steric hindrance. Generally, with increasing PVP concentration, mono-dispersed colloidal solutions were obtained and at the optimal PVP concentration (5%), sufficiently small size and narrow size distributions were obtained from both sodium sulfide and thioacetamide sulfur sources. Finally, the sulfur source directly influences the reaction mechanism and the final particle morphology, as well as the average size.     

Fabrication of transparent super-hydrophilic coatings with self-cleaning and anti-fogging properties by using dendritic nano-silica

In this paper, super-hydrophilic coatings were generated on glass substrates via dipping method using colloidal silica with different morphologies as the main raw materials. The coatings were characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FE-SEM), water contact angle (WCA) analyzer, and atomic force microscope (AFM). The hardness, adhesion, self-cleaning and antifogging properties of the coatings were examined. It has been found that the hydrophilicity of the coating can be significantly improved by using dendritic silica nanoparticles, and the comprehensive performance of the coating is optimum when the branch length of dendritic silica nanoparticles is about 60 nm. The coatings show super-hydrophilicity (CA, 1.7°), and high transmittance (the maximum light transmittance of the coating on glass is increased by 2.2%). Moreover, the coating is very effective in eliminating fog and dirt. The hardness and the adhesion of the coating can be reached 9H and grade 0, respectively, indicating that the coatings have a good mechanical performance, which is essential for its application.     

Preparation of Raspberry-Like Adsorbed Silica Nanoparticles via Miniemulsion Polymerization Using a Glycerol-Functionalized Silica Sol

A series of polymer/SiO₂ organic-inorganic composite microspheres were successfully prepared through miniemulsion polymerization. A TEM study indicated that the composite microspheres had raspberry-like morphology and silica particles were successfully deposited onto the surfaces of organic polymer microspheres. The average particle size and the silica content of composite microspheres could range from 180 nm to 240 nm and 15 ～ 35 wt%, respectively. The influence of reaction conditions such as the amount of emulsifier, the sonification frequency and sonification time, the amount of silica sol, butyl acrylate (BA) on the particle size, silica content and morphology of composite microspheres have been studied.     

One-pot fabrication of robust hydrophobia and superoleophilic cotton fabrics for effective oil-water separation

A one-pot sonochemical irradiation method was developed for the fabrication of superhydrophobic and superoleophilic cotton fabric from a solution consisting of branched silica nanoparticles and tetraethoxysilane-dodecyltrimethoxysilane sol. The silica/sol-coated cotton fabric could be wetted by liquids of low surface tension, but was water repellent with a water contact angle of 159 ± 1.2° and water shedding angle of 6 ± 0.8°. The as-prepared cotton fabric could be used as effective materials for the separation of oil from water with separation efficiency as high as 98.2% and maintained separation efficiency above 94% after 30 separation cycles for the kerosene-water mixture. Moreover, the superhydrophobic and superoleophilic cotton fabric could maintain stable superhydrophobicity after treatment with strong acidic and alkali solutions, and harsh mechanical damage. Therefore, this reported robust superhydrophobic cotton fabric exhibits encouraging practical application for oil-water separation.     

Preparation of doubly responsive polymer functionalized silica hybrid nanoparticles via a one‐pot thiol‐isocyanate click reaction at room temperature

Well‐defined poly(N‐isopropylacrylamide) and poly(2‐(diethylamino) ethyl methacrylate) were synthesized first by a reversible addition‐fragmentation chain transfer process. These polymers were then reduced to generate an end thiol group to react with isocyanate groups on the surface of silica nanoparticles, which were pretreated with toluene‐2,4‐diisocyanate, by a one‐pot “click” reaction to prepare temperature and pH responsive polymer functionalized hybrid silica nanoparticles. The polymer functionalized silica hybrid nanoparticles were characterized by a range of techniques such as Fourier transform infrared spectroscopy and dynamic light scattering. The doubly responsive polymer functionalized silica hybrid nanoparticles show both temperature and pH responsive behavior and their solution properties were dependent on the ratio of the two polymers on the surface of silica. Covalent functionalization of the silica nanoparticle with well‐defined temperature and pH responsive polymers was accomplished via a one‐pot thiol‐isocyanate click reaction. This reaction was found to be extremely efficient in producing doubly responsive polymer functionalized silica hybrid nanoparticle, even at relatively low reaction temperature and short reaction time. Thermogravimetric analysis indicated that the same ratio of poly(N‐isopropylacrylamide) and poly(2‐(diethylamino)ethyl methacrylate) functionalized silica hybrid nanoparticle consisted of 42.46 wt% polymer. POLYM. COMPOS., 38:1454–1461, 2017. © 2015 Society of Plastics Engineers     

荧光胺定量检测纳米SiO2表面氨基的含量

首先用3-氨丙基三乙氧基硅烷偶联剂(APTES)在一定条件下接枝于纳米二氧化硅表面,并采用傅里叶变换红外光谱仪(FI-IR)进行测试表征,建立了一种用荧光胺定量检测功能化纳米SiO2表面氨基的方法,并通过优化实验建立该检测方法的测试标准.最佳检测条件为:室温下,激发波长380 nm、发射波长480 nm,荧光胺的丙酮溶液与磷酸盐缓冲液体积比1:5,磷酸盐缓冲液pH值为10.0,反应时间为10 min等条件下,荧光信号最稳定.采用该最佳条件下制定的标准曲线对功能化纳米SiO2微球进行检测,结果符合预期,该方法检测灵敏度高、操作简单.     

Grafting of water‐soluble sulfonated monomers onto functionalized fumed silica nanoparticles via surface‐initiated redox polymerization in aqueous medium

Sulfonated polymer/fumed silica hybrid nanoparticles were prepared via surface‐initiated free radical polymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (PAMPS‐g‐FSN), styrene sulfonic acid sodium salt (PSSA‐g‐FSN) and vinyl sulfonic acid sodium salt (PVSA‐g‐FSN) from the surface of aminopropyl‐functionalized fumed silica nanoparticles (AFSNs) dispersed in aqueous medium. Cerium(IV) ammonium nitrate/nitric acid and sodium dodecyl sulfate were used as redox initiator and stabilizer respectively. AFSNs were prepared by covalently attaching 3‐aminopropyltriethoxysilane onto the surface of fumed silica nanoparticles. Sulfonated monomers (AMPS, SSA or VSA) were then grafted onto the AFSNs ultrasonically dispersed in water via redox initiation at 40 °C. Structure, thermal properties, particle size and morphology of the AFSNs and PAMPS‐g‐FSN, PSSA‐g‐FSN and PVSA‐g‐FSN hybrid nanoparticles were characterized by Fourier transform infrared spectroscopy, TGA, SEM, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results indicated that the sulfonated monomers were successfully grafted onto the fumed silica nanoparticles. Grafting amounts of the sulfonated polymers onto the fumed silica nanoparticle surface were estimated from TGA thermograms to be 59%, 13% and 29% for the PAMPS, PSSA and PVSA, respectively. From SEM, TEM and DLS analysis, polymer‐grafted fumed silica nanoparticles with an average diameter smaller than 70 nm and a (semi‐) spherical shape were observed. A significant bimodal particle size distribution was observed only for the PAMPS‐g‐FSN with average diameters of 39.6 nm (84.1% per number) and 106 nm (15.9% per number). The hydrophilic sulfonated polymer/grafted fumed silica obtained from the redox graft polymerization gave a stable colloidal dispersion in acidic aqueous medium. Copyright © 2012 Society of Chemical Industry     

Ultrasonic dual mode mixing and its effect on tensile properties of SiO2-epoxy nanocomposite

Dispersion of nanoparticles and its effect on the tensile properties were investigated by preparing nanocomposites via mechanical mixing (MM) and optimized ultrasonic dual mode mixing (UDMM) routes. The MM of SiO₂ nanoparticles in epoxy resin was employed using glass rod stirring and the UDMM was employed by ultrasonic vibration along with magnetic stirring to produce SiO₂-epoxy nanocomposite. Taguchi method was used for optimization of the process parameters of UDMM route considering the tensile strength of the base epoxy. Field emission scanning electron microscopy (FE-SEM) micrographs revealed an improved dispersion quality of SiO₂ nanoparticles especially for the UDMM route. Consequently, quality of dispersion affects tensile strength (max 49.2%) along with ductility and absorbed failure energy at low nanoparticle content. Moreover, elastic modulus increases with increasing content of nanoparticle, e.g. in one case 62.55% for 20?wt.% of SiO₂ nanoparticles.     

Nanoparticle formation through solid‐fed flame synthesis: Experiment and modeling

The preparation of silica nanoparticles through solid‐fed flame synthesis was investigated experimentally and theoretically. Monodispersed submicrometer‐ and micrometer‐sized silica powders were selected as solid precursors for feeding into a flame reactor. The effects of flame temperature, residence time, and precursor particle size were investigated systematically. Silica nanoparticles were formed by the nucleation, coagulation, and surface growth of the generated silica vapors due to the solid precursor evaporation. Numerical modeling was conducted to describe the mechanism of nanoparticle formation. Evaporation of the initial silica particles was considered in the modeling, accounting for its size evolution. Simultaneous mass transfer modeling due to the silica evaporation was solved in combination with a general dynamics equation solution. The modeling and experimental results were in agreement. Both results showed that the methane flow rate, carrier gas flow rate, and initial particle size influenced the effectiveness of nanoparticle formation in solid‐fed flame synthesis. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Influence of different nanoparticles on the gas injection performance in EOR operation: Parametric and CFD simulation study

This study aims to simulate the process of enhanced oil recovery (EOR) during gas injection along with nanoparticles and investigate the affecting parameters in a conventional carbonate oil reservoir. Ansys Fluent software with a suitable multiphase model was used to simulate natural gas injection with a nanoparticle into a core sample. The simulation model was validated with a laboratory test of natural gas injection. Then, to obtain the optimal values of each of the parameters affecting the process of EOR during the natural gas injection along with nanoparticles, the design of the experiment was carried out with the help of Qualitek-4 software and the Taguchi method. Therefore, three factors, including nanoparticle type (clay, titanium oxide, and silica nanoparticles), nanoparticle diameter (2–50 nm), and the volume fraction of nanoparticles in the base fluid (0.5–5 vol.%), as influential factors on the EOR during natural gas injection along with nanoparticles were chosen. The results of the numerical study indicated that silica nanoparticles significantly affect EOR more than clay and titanium oxide nanoparticles. Moreover, the smaller the diameter of nanoparticles (close to 2 nm) and the more significant the volume fraction of nanoparticles in the base fluid (close to 5 vol.%), the higher the oil recovery factor will be. This phenomenon occurs due to changes in the density and viscosity of the base fluid and, consequently, improves the mobility ratio of the injected fluid. On the other hand, the tiny size of nanoparticles allows them to easily enter the pores of the reservoir rock without entrapping and producing oil from them. Eventually, the highest oil recovery factor (59%) was obtained using silica nanoparticles with a diameter of 2 nm and a volume fraction of 5 vol.% in natural gas injection.