Solid–Liquid Work of Adhesion Tadmor, Rafael; Das, Ratul; Gulec, Semih ...
Langmuir,
04/2017, Letnik:
33, Številka:
15
Journal Article
Recenzirano
We establish a tool for direct measurements of the work needed to separate a liquid from a solid. This method mimics a pendant drop that is subjected to a gravitational force that is slowly ...increasing until the solid–liquid contact area starts to shrink spontaneously. The work of separation is then calculated in analogy to Tate’s law. The values obtained for the work of separation are independent of drop size and are in agreement with Dupré’s theory, showing that they are equal to the work of adhesion.
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In this paper we show a way that allows for the first time to induce arbitrary humidity of desired value for systems without convective flow. To enable this novelty we utilize a ...semi-closed environment in which evaporation is not completely suppressed. In this case, the evaporation rate is determined both by the outer (open) humidity and by the inner (semi-closed) geometry including the size/shape of the evaporating medium and the size/shape of the semi-closure. We show how such systems can be used to induce desired humidity conditions. We consider water droplet placed on a solid surface and study its evaporation when it is surrounded by other drops, hereon “satellite” drops and covered by a semi-closed hemisphere. The main drop’s evaporation rate is proportional to its height, in agreement with theory. Surprisingly, however, the influence of the satellite drops on the main drop’s evaporation suppression is not proportional to the sum of heights of the satellite drops. Instead, it shows proportionality close to the satellite drops’ total surface area. The resultant humidity conditions in the semi-closed system can be effectively and accurately induced using different satellite drops combinations.
With the increasing awareness of the serious pollution from the usage of fossil fuels and the fast advances of technologies, the usage of biomass has been increased significantly. In this review ...paper, the biomass serving as carbon precursors and the energy has been reviewed including lotus lives, wheat flour, fish scale, fish skin, wax gourd, etc. The formed carbon nanostructures are reviewed together with their applications including the treatment volatile organic compounds (VOCs), heavy metal ions from polluted water, spilled oil, fillers for advanced composites, etc. This paper gives the usage of biomass in a sustainable and green way.
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Laser-induced graphene (LIG) has attracted extensive research as an electrode material for micro-supercapacitors (MSC). However, the low capacitive performance of LIG arising from both limited ...specific surface area and few active sites remains challenging. Herein, in situ doping of fluorine and boron atoms into laser-induced graphene was innovatively achieved via laser direct writing approach using boron-doped fluorinated polyimide (FB-PI) as the precursor. The porous fluorine and boron co-doped laser-induced graphene (FB-LIG) exhibits more active sites and improved wettability and significantly enhanced capacitive performance due to the synergistic effect of fluorine and boron co-doping. By tuning the weight ratio of boron to fluorine, the MSC utilizing FB-LIG as the electrode and poly(vinyl alcohol) (PVA)/H2SO4 as the gel electrolyte delivers a high areal capacitance of 49.81 mF/cm2 at a current density of 0.09 mA/cm2, 23 times higher that of MSC from commercial polyimide (PI)-based LIG, and 3 times that of MSC from fluorinated PI-based LIG. In addition, MSCs from FB-LIG possess excellent mechanical stability and flexibility, rendering them promising for flexible wearable microelectronics.
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•In-situ doping of F/B is achieved by laser direct writing process.•The prepared F/B co-doped porous graphene has high specific surface area and abundant active sites.•The synergistic effect of F/B resulted in a high areal capacitance of 49.81 mF/cm2.
As a new type of 2D materials, MXene has the features of good conductivity and high specific surface area. Layered double hydroxide (LDH) is often used in the field of supercapacitors owing to its ...special layered structure, strong adjustability, and large specific capacitance. In recent years, many researchers have combined MXenes and LDHs to prepare electrode materials with high capacitance performance and studied their preparation methods, morphology, and electrochemical properties. This study summarizes the fabrication methods of MXenes and LDHs, as well as the recent progress of MXene/LDH composites in the field of supercapacitors in recent years. Moreover, the corresponding study direction on supercapacitors has been prospected. This study aims to illustrate the application of MXene/LDH composites for supercapacitors and hopes to offer guidance for further research on the basis of these promising materials.
In this study, the preparation methods of MXenes and layered dihydroxides (LDHs) are reviewed. In addition, the preparation and the electrochemical performances for supercapacitors of MXene/LDHs composites are summarized in detail.
•High conductivity membrane with double proton site at low humidity was designed.•This dual proton-conducting structure provided higher proton concentration.•Distinct phase separation for ...facilitating proton transport was constructed.•The PFC2-TF-SI membrane exhibited 10.6 mS/cm of proton conductivity at 30% RH and 80 °C.•The fuel cell was built from this membrane and their performances were studied.
Structural optimization of ionomers is an effective strategy for achieving high-performance proton exchange membranes (PEMs) under low relative humidity (RH) conditions. In this study, sulfonimide group and trifluoromethanesulfonate acid (TFSA) ionic liquids were introduced to the perfluorosulfonic acid (PFSA) side chain, resulting in polymer membranes with varying chain lengths (i.e., PFC2-TF-SI, PFC4-TF-SI, and PFC5-TF-SI). This dual proton-conducting structure extended the length of the hydrophilic side chain and enhanced the hydrophobic-hydrophilic phase separation, aiding in the formation of proton transport channels. Notably, the proton conductivity of PFC5-TF-SI and PFC2-TF-SI membranes reached 7.1 and 10.6 mS/cm at 30% RH and 80 °C, respectively, which were approximately 29.1% and 92.7% higher than that of the pristine PFC5-SA membrane (5.5 mS/cm). Furthermore, the maximum power density of the PFC5-TF-SI and PFC2-TF-SI membranes from the built single fuel cell achieved 649 and 763 mW/cm2 at 30% RH and 80 °C, respectively, which were higher than that of the pristine PFC5-SA membrane (567 mW/cm2) by about 14.5% and 34.6%, respectively. Thus, this study provides a strategy for PEM design under low RH conditions.
Cured epoxy is stable and difficult to be recycled. To make the inert cured epoxy and its derivatives or composites reactive is still a challenge. In this study, sub-critical water was used to ...decompose the solid diglycidyl ether-based epoxy resin (bisphenol A and bisphenol F) cured with triethylene tetramine (TETA) to reactive species. First of all, the thermally most unstable bonds in the epoxy resin underwent homogeneous cleavage reaction. Next, the generated free radicals were saturated by extracting hydrogen from the sub-critical water. The decomposition rate was improved with increasing the temperature and reaction time. During the reaction, breakage occurs preferentially in the epoxy resin main chain because of the existence of ether groups. The compounds evolved and the decomposition was analyzed. The experimental outcomes revealed that the decomposition mechanism of diglycidylether of bisphenol A (DGEBA)/TETA and diglycidylether of bisphenol F (DGEBF)/TETA resin regimes in sub-critical water may include side group elimination, random fracture and unzipping. Moreover, a segmented second-order kinetic analysis of the decomposition process was performed. The decomposition processes of two resins in sub-critical water were divided into two stages. Both stages were second-order reaction, the activation energy of DGEBA/TETA was 175 kJ/mol (Ea1(15-45min)), and 612 kJ/mol (Ea2(52.5-75min)). The activation energy of DGEBF/TETA was 258 kJ/mol (Ea1(15-45min)), and 686 kJ/mol (Ea2(52.5-75min)), respectively. This study provides a way for recycling inert epoxy wastes from different industrial fields and generating reactive and functional polymers.
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•Inert epoxies are successfully decomposed in sub-critical water.•Phenols and bisphenols are formed by decomposing diglycidylether of bisphenol A/triethylene tetramine (TETA) and diglycidylether of bisphenol F/TETA systems.•The decomposition mechanisms are obtained.•Different stages of the reactions are described with kinetic models.
Abstract
The modified waterborne acrylic resin was synthesized successfully by emulsion polymerization with octafluoropentyl methacrylate and phosphate functional monomer as monomers, showing an ...improved anti‐corrosion performance of the resin coating. The existence and general distribution of the elements of the modified monomer in the emulsion were explored, and the anti‐corrosion mechanism was disclosed. The results show that the modification of octafluoropentyl methacrylate and phosphate functional monomers improved the water resistance, corrosion resistance and thermal stability of acrylic resins. Compared with unmodified acrylic resin, the contact angle of the modified resin was increased from 74.23° to 83.51°, and the initial decomposition temperature was increased from 264 to 305 °C. At the same time, the corrosion voltage of the modified resin was increased, the corrosion current density was decreased, and the salt spray resistance was improved. This study provides a new way for the preparation of environmentally friendly, stable, and corrosion‐resistant waterborne acrylic resins.
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