Tailoring intrinsic hydrophobicity and surface energy on rough surface via low-T Cassie–Wenzel wetting transition method

Wettability is an important parameter of micro/nanostructured composites. The measurement of apparent contact angle is strongly affected by surface roughness, which induces some challenges to study the intrinsic hydrophobicity correlating to the nature of chemistry. Carbon-Nafion composites exhibited about 30° decrease in apparent contact angle from 30 to 10°C due to the condensation of water vapor into cavities, suggesting a significant Cassie–Wenzel wetting transition phenomenon. The focus of this work has been on the first-time use of a low-T Cassie–Wenzel wetting transition method to evaluate Young's (ideal) contact angle and surface free energy. A maximum Young's contact angle (113°) and minimum total surface energy (12 mJ/m²) were determined at Nafion content of 70 wt%, indicating the orientation effect that sulfonate groups in Nafion preferentially pointed toward polar carbon. This approach provided the reasonable prediction of intrinsic hydrophobicity, especially when a rough solid surface is not easily wetted by liquids.     

A Universal Strategy of Perovskite Ink - Substrate Interaction to Overcome the Poor Wettability of a Self-Assembled Monolayer for Reproducible Perovskite Solar Cells

Perovskite solar cells employing [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) self-assembled monolayer as the hole transport layer have been reported to demonstrate a high device efficiency. However, the poor perovskite wetting on Me-4PACz caused by poor perovskite ink interaction with the underlying Me-4PACz presents significant challenges for fabricating efficient perovskite devices. A triple co-solvent system comprising dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP) is employed to improve the perovskite ink - Me-4PACz coated substrate interaction and obtain a uniform perovskite layer. In comparison to DMF- and DMSO-based inks, the inclusion of NMP shows considerably higher binding energies of the perovskite ink with Me-4PACz as revealed by density-functional theory calculations. With the optimized triple co-solvent ratio, the perovskite devices deliver high power conversion efficiencies of >20%, 19.5%, and ≈18.5% for active areas of 0.16, 0.72, and 1.08 cm², respectively. Importantly, this perovskite ink–substrate interaction approach is universal and helps in obtaining a uniform layer and high photovoltaic device performance for other perovskite compositions such as MAPbI₃, FA_1−xMA_xPbI_3–yBr_y, and MA-free FA_1−xCs_xPbI_3–yBr_y.     

Monitoring cheese ripening by single-sided nuclear magnetic resonance

The noninvasive, longitudinal study of products and food processing is of interest for the dairy industry. Here, we demonstrated that single-sided nuclear magnetic resonance (NMR) can be used for noninvasive monitoring of the cheese ripening process. The maturation of soft-ripened Camembert-like molded cheese samples was monitored for 20 d measuring 1-dimensional and 2-dimensional NMR relaxation and diffusion data at various depths, ranging from the hard surface layer to the soft center. Gelation and gel shrinkage were observed throughout ripening, and a complete loss of free water signal was observed at the cheese rind. Transversal (T₂) relaxation distributions include 3 components that evolve with ripening time and position, corresponding to water inside the casein gel network, water trapped in casein, and fat. Two-dimensional T₁-T₂ relaxation experiments provided enhanced resolution of the 3 components, allowing quantification of the relative proportions of each phase. Furthermore, diffusion (D)-T₂ relaxation correlation experiments revealed the bimodal size distribution of fat globules. The study demonstrated that single-sided NMR can provide spatially resolved signal intensity, relaxation, and diffusion parameters that reflect structural changes during the ripening process and can be exploited to understand and monitor the ripening of cheeses.     

Morphology-Tailored Hydroxyapatite Nanocarrier for Rhizosphere-Targeted Phosphorus Delivery

High hydrophilicity and soil fixation collectively hamper the delivery of phosphorus (P) released from conventional chemical phosphorus fertilizers (CPFs) to plant rhizosphere for efficient uptake. Here, a phosphorus nutrient nanocarrier (PNC) based on morphology-tailored nanohydroxyapatite (HAP) is constructed. By virtue of kinetic control of building blocks with designed calcium phosphate intermediates, rod-like and hexagonal prism-like PNCs are synthesized, both having satisfactory hydrophobicity (water contact angle of 105.4^–132.9°) and zeta potential (−17.43 to −58.4 mV at pH range from 3 to 13). Greenhouse experiments demonstrate that the P contents increase by up to 183% in maize rhizosphere and up to 16% in maize biomass when compared to the CPF. Due to the water potential gradient driven by photosynthesis and transpiration, both PNCs are stably transported to maize rhizosphere, and they are capable to counteract soil fixation prior to uptake by plant roots. Within the synergies of the HAP morphological characteristics and triggered phosphate starvation response, root anatomy confirms that two pathways are elucidated to enhance plant P replenishment from the PNCs. Together with structure tunability and facile synthesis, our results offer a new nanodelivery prototype to accommodate plant physiological traits by tailoring the morphology of HAP.     

Improving water transport through sub-nanometer channels by alternating hydrophilic–hydrophobic patterns

Hydrophilicity is key factor to sub-nanometer channels for water transport. However, how to effectively integrate the respective advantages of hydrophilicity and hydrophobicity to realize ultrafast water transport at the sub-nanometer scale is still confusing. By using sub-nanometer channels formed by two-dimensional covalent organic frameworks as typical models, we herein demonstrate that alternating hydrophilic–hydrophobic patterns in channels are capable of significantly improving water transport. Alternatingly stacking hydrophilic and hydrophobic monolayers is testified to be energetically favorable to directly piling their multilayers. Meanwhile, alternatingly-stacked hydrophilic–hydrophobic multilayers are able to achieve much higher water permeability than individual hydrophilic or hydrophobic multilayers. The effect of framework flexibility is also investigated. The exceptional performances benefit from the perfect balance between excellent wettability of hydrophilicity and low friction of hydrophobicity. In order to give full play to the synergistic advantages, the thickness of hydrophobic patterns spaced by hydrophilic ones should be less than 1 nm.     

老化对PTFE/PPS复合涂层的疏水和防结冰性能的影响

目的 飞机表面涂层在服役过程中受到高温、太阳光辐射作用，容易引起微观结构的破坏，失去原有的性能。本文探究了老化对PTFE/PPS复合涂层疏水、防结冰性能的影响。方法 利用一步喷涂法在TC4基体上制备出PTFE/PPS复合涂层，使用SEM和三维形貌仪进行表面形貌分析，利用傅里叶红外光谱仪以及XPS分析涂层元素组成，在对制得的PTFE/PPS复合涂层进行高温热老化（24、48、96 h）以及太阳辐射光老化（24、48、96 h）实验后，对其进行疏水防结冰性能测试。结果 原始的PTFE/PPS复合涂层和经过24、48、72高温热老化后PTFE/PPS复合涂层的表面粗糙度分别为8.075μm、5.383μm、4.583μm、5.466μm，静态水接触角由139.70°降至132.36°、131.13°、130.36°，结冰时间由最初的346 s缩短至326 s、309 s、294 s，冰晶黏附力由最初的8.65 N增加至8.90 N、9.15 N、9.65 N。经过24、48、72 h太阳辐射光老化后，PTFE/PPS复合涂层的表面粗糙度分别为10.549μm、10.974μm、9.969μm...