共查询到9条相似文献,搜索用时 15 毫秒
1.
Fabrication of Robust Hydrophobic and Super‐Hydrophobic Polymer Films with Onefold or Dual Inverse Opal Structures 下载免费PDF全文
Hydrophobic and super‐hydrophobic materials have many important applications, but most of the artificially hydrophobic and super‐hydrophobic surfaces suffer from poor durability. Herein, a facile method is reported to fabricate robust hydrophobic and super‐hydrophobic polymer films through backfilling the silica colloidal crystal templates with the mixture of fluoropolymer, thermoset hydroxyl acrylate resins, and curing agent. After removal of the template, 3D ordered porous structures are obtained. The obtained polymer films have not only excellent hydrophobic or super‐hydrophobic properties but also good stability against temperatures, acids, and alkalis. Dual ordered porous structure can obviously enhance the hydrophobicity of polymer films compared to unitary one.
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Potassium–Sodium Niobate‐Based Lead‐Free Piezoelectric Ceramic Coatings by Thermal Spray Process 下载免费PDF全文
Shuting Chen Chee Kiang Ivan Tan Kui Yao 《Journal of the American Ceramic Society》2016,99(10):3293-3299
Potassium–sodium niobate (KNN)‐based piezoelectric ceramic coatings with single perovskite phase and dense morphology were obtained by thermal spray processing. The structure, morphology, and properties of the coatings deposited at different conditions were investigated, and excellent piezoelectric performance properties were demonstrated. The piezoelectric coefficient observed in the KNN‐based coatings in this study is about one order of magnitude higher than other thermal sprayed lead‐free piezoelectric coatings as reported in literature. With analyses on the differences in the characteristics between KNN and lead zirconate titanate (PZT) compositions and the reaction mechanisms of thermal spray and ceramic synthesis, the reasons for the successful formation of single‐phase perovskite structure with high crystallinity in the thermal sprayed KNN‐based coatings while not in PZT are explained. 相似文献
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Sean P. Bew G. Richard Stephenson Jacques Rouden Polly‐Anna Ashford Manuel Bourane Agathe Charvet Virginie M. D. Dalstein Raphael Jauseau G. D. Hiatt‐Gipson Luis A. Martinez‐Lozano 《Advanced Synthesis \u0026amp; Catalysis》2015,357(6):1245-1257
Utilizing ‘off the shelf’ commercially available, cheap, small synthetic molecules that mimic the efficient mediation of important bioreactions utilized by Nature is not only highly sought after but also currently highly topical. This paper details our preliminary efforts at developing a unique base‐ and metal‐free phase‐transfer‐mediated malonic acid thioester (MAHT) ‘activation protocol’ that efficiently generates (±)‐β‐thioesters. Our bioinspired aldol process is exceptionally mild, conducted under near neutral pH reaction conditions, does not require an inert, oxygen‐free atmosphere or anhydrous reaction conditions and is highly atom‐economic. Exemplifying the utility of our protocol, the synthesis of an array of structurally and functionally diverse (±)‐β‐hydroxy thioesters equipped with highly prized functionality, i.e., chlorine, bromine, fluorine, nitrile and nitro groups, is reported, as is the diastereoselective potential of this important reaction.
4.
Liangliang Shi Xiaobo Yang Yuyuan Wang Haijun Yang Hua Fu 《Advanced Synthesis \u0026amp; Catalysis》2014,356(5):1021-1028
A novel, simple and highly efficient method for the synthesis of 3‐(trifluoromethyl)‐indolin‐2‐one derivatives has been developed. The protocol uses readily available N‐alkyl‐N‐phenylacrylamides as the starting materials, inexpensive and easily stored Langlois reagent (sodium trifluoromethanesulfinate) as the trifluoromethyl source, and iodobenzene diacetate [PhI(OAc)2] as the oxidant. The procedure involves a metal‐free domino trifluoromethylation and arylation of alkenes. The methods did not need mediation of any transition metal which avoided contaminations of toxic metals in the products.
5.
Jonathan T. Essel Andrew C. Cortopassi Kenneth K. Kuo Christopher G. Leh James H. Adair 《Propellants, Explosives, Pyrotechnics》2012,37(6):699-706
It has been shown that nano‐sized particles of secondary explosives are less sensitive to impact and can alter the energetic performance of a propellant or explosive. In this work the Rapid Expansion of a Supercritical Solution into an Aqueous Solution (RESS‐AS) process was used to produce nano‐sized RDX (cyclo‐1,3,5‐trimethylene‐2,4,6‐trinitramine) particles. When a saturated supercritical carbon dioxide/RDX solution was expanded into neat water, RDX particles produced from the RESS‐AS process agglomerated quickly and coarsened through Ostwald ripening. However, if the pH level of the suspension was changed to 7, particles were metastably dispersed with a diameter of 30 nm. When the supercritical solution was expanded into air under the same pre‐expansion conditions using the similar RESS process, RDX particles were agglomerated and had an average size of approximately 100 nm. Another advantage of using a liquid receiving solution is the possibility for coating energetic particles with a thin layer of polymer. Dispersed particles were formed by coating the RDX particles with the water soluble polymers polyvinylpyrrolidone (PVP) or polyethylenimine (PEI) in the RESS‐AS process. Both PVP and PEI were used because they have an affinity to the RDX surface. Small and well‐dispersed particles were created for both cases with both PVP and PEI‐coated RDX particles shown to be stable for a year afterward. Several benefits are expected from these small polymer coated RDX particles such as decreased sensitivity, controlled reactivity, and enhanced compatibility with other binders for fabrication of bulk‐sized propellants and/or explosives. 相似文献
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Sandip T. Gadge Mayur V. Khedkar Satish R. Lanke Bhalchandra M. Bhanage 《Advanced Synthesis \u0026amp; Catalysis》2012,354(10):2049-2056
Palladium‐on‐carbon (Pd/C)‐catalyzed oxidative aminocarbonylations of alk‐1‐ynes with secondary amines provide the corresponding alk‐2‐ynamides in a good to excellent yields. This new methodology is applicable for the synthesis of a wide range of biologically active alk‐2‐ynamide derivatives. The developed protocol avoids the use of phosphine ligands, with an additional advantage of palladium catalyst recovery and reuse for up to four consecutive cycles. 相似文献
8.
Sealing Glass‐Ceramics with Near Linear Thermal Strain,Part I: Process Development and Phase Identification 下载免费PDF全文
Steve Dai Mark A. Rodriguez James J. M. Griego 《Journal of the American Ceramic Society》2016,99(11):3719-3725
A widely adopted approach to form matched seals in metals having high coefficient of thermal expansion (CTE), e.g. stainless steel, is the use of high CTE glass‐ceramics. With the nucleation and growth of Cristobalite as the main high‐expansion crystalline phase, the CTE of recrystallizable lithium silicate Li2O–SiO2–Al2O3–K2O–B2O3–P2O5–ZnO glass‐ceramic can approach 18 ppm/°C, matching closely to the 18 ppm/°C–20 ppm/°C CTE of 304L stainless steel. However, a large volume change induced by the α‐β inversion between the low‐ and high‐ Cristobalite, a 1st order displacive phase transition, results in a nonlinear step‐like change in the thermal strain of glass‐ceramics. The sudden change in the thermal strain causes a substantial transient mismatch between the glass‐ceramic and stainless steel. In this study, we developed new thermal profiles based on the SiO2 phase diagram to crystallize both Quartz and Cristobalite as high expansion crystalline phases in the glass‐ceramics. A key step in the thermal profile is the rapid cooling of glass‐ceramic from the peak sealing temperature to suppress crystallization of Cristobalite. The rapid cooling of the glass‐ceramic to an initial lower hold temperature is conducive to Quartz crystallization. After Quartz formation, a subsequent crystallization of Cristobalite is performed at a higher hold temperature. Quantitative X‐ray diffraction analysis of a series of quenched glass‐ceramic samples clearly revealed the sequence of crystallization in the new thermal profile. The coexistence of two significantly reduced volume changes, one at ~220°C from Cristobalite inversion and the other at ~470°C from Quartz inversion, greatly improves the linearity of the thermal strains of the glass‐ceramics, and is expected to improve the thermal strain match between glass‐ceramics and stainless steel over the sealing cycle. 相似文献
9.
Wienke Reynolds Victor Baudron Christian Kirsch Lisa M. Schmidt Hannah Singer Lilia Zenker Carsten Zetzl Irina Smirnova 《化学,工程师,技术》2016,88(10):1513-1517
In this work a process for the production of odor‐free lignin from wheat straw using solely water, enzymes and CO2 is described. Wheat straw pellets are pretreated by liquid hot water and enzymatic hydrolysis in a pilot plant with a capacity of 40 L, which enables the production of 3 – 4 kg of Aquasolv lignin per batch. Dried lignin samples are further treated using supercritical CO2, resulting into extraction of a large number of odorous free fatty acids and volatile organic compounds. All process steps can be sequentially conducted in a fixed‐bed via different sustainable solvents in a throughput regime. 相似文献