scholarly journals Synthesis of Porous Particles by Electrospray-Assisted Self-Assembly for Water-Repellent or Photocatalytic Surfaces

2020 ◽  
Vol 58 (2) ◽  
pp. 112-124
Author(s):  
Young-Sang Cho ◽  
Younghyun Lee ◽  
Nahee Ku ◽  
Sugueun Ji ◽  
Young Seok Kim
Keyword(s):  
Porous Ceramic ◽  
Ambient Air ◽  
Water Repellent ◽  
Volatile Components ◽  
Coating Film ◽  
Water Contact ◽  
Ceramic Particles ◽  
Templating Method ◽  
Porous Particles ◽  
Polystyrene Nanospheres

In this study, an electrospray technique was used for the synthesis of macroporous ceramic particles, such as silica or titania, by a colloidal templating method. For this purpose, a suspension of polystyrene nanospheres was synthesized by dispersion polymerization for use as sacrificial templates. The feed solution containing a ceramic precursor and polymeric beads was injected through a metallic nozzle under a high electric field for nebulization of aerosol droplets as micro-reactors. Under ambient air conditions, the volatile components were evaporated from the droplets, and gelation of the precursor was completed simultaneously. The resulting supra-aggregates were then collected, and calcination was performed to form porous ceramic particles by removing the polymeric templates. As a demonstrative application, the porous particles of silica were deposited as a coating film for superhydrophobic surfaces with a high water contact angle larger than 150°. Furthermore, macroporous titania particles were used as photocatalytic particles in a wastewater system with first-order reaction kinetics.

Fabrication of Super Water-Repellent Surfaces by Nanosphere Lithography

2004 ◽  
Vol 823 ◽  
Author(s):  
Jau-Ye Shiu ◽  
Chun-Wen Kuo ◽  
Peilin Chen ◽  
Chung-Yuan Mou
Keyword(s):  
Plasma Etching ◽  
Oxygen Plasma ◽  
Nanosphere Lithography ◽  
Contact Angles ◽  
Adjustable Parameter ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Water Contact ◽  
Polystyrene Nanospheres ◽  
Plant Surfaces

Abstract: Inspired by the water-repellent behavior of the micro- and nano-structured plant surfaces, superhydrophobic materials, with a water contact larger than 150° superhydrophobic surfaces using a combination of nanosphere lithography and plasma etching. It has been found that the water contact angle on these surfaces can be systematically tuned from 132° to 168° by trimming the diameters of polystyrene nanospheres using oxygen plasma. The water contact angles measured on these surfaces can be modeled by the Cassie's formulation without any adjustable parameter.

Local Strengthening of EN AC-44200 Al Alloy with Ceramic Fibers

2015 ◽  
Vol 662 ◽  
pp. 237-240 ◽  
Author(s):  
Krzysztof Naplocha ◽  
Jacek W. Kaczmar ◽  
Jerzy Morgiel
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Composite Materials ◽  
Squeeze Casting ◽  
Porous Ceramic ◽  
Al Alloy ◽  
Ceramic Fibers ◽  
Ceramic Particles ◽  
Casting Technique ◽  
University Of Technology

The applied squeeze casting technique makes possible the local strengthening with ceramic fibers or ceramic particles of elements with Al-alloy matrices. In this paper the elaborated technology of manufacturing of porous ceramic preforms from Saffil fibers is shown and technology of squeeze casting elaborated at Wrocław University of Technology, Chair Foundry, Polymers and Automation described. There were applied the preforms characterized by porosities of 90% and 80%, what after squeeze casting with liquid EN AC - 44200 Al alloy produces the composite materials containing 10 vol. and 20 vol.% of fiber strengthening. The structural phenomena at the interface of strengthened alloy investigated with the optical and electron microscopy are discussed and the mechanical properties of manufactured composite materials are shown.

Fast and simple fabrication of SiO2/poly(vinylidene fluoride) coated cotton fabrics with asymmetric wettability via a facile spray-coating route

2018 ◽  
Vol 89 (6) ◽  
pp. 1013-1026 ◽  
Author(s):  
Rongrong Yu ◽  
Mingwei Tian ◽  
Lijun Qu ◽  
Shifeng Zhu ◽  
Jianhua Ran ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Contact Angle ◽  
Water Contact Angle ◽  
Vinylidene Fluoride ◽  
Spray Coating ◽  
Cotton Fabrics ◽  
Water Repellent ◽  
Water Contact ◽  
Repellent Property ◽  
Poly Vinylidene Fluoride

Cotton fabrics with hydrophilic-to-hydrophobic asymmetric surfaces are attractive as potential utilizable structures for functional garments. The spray-coating route could be deemed as a fast and simple way to achieve asymmetric surfaces. In this paper, SiO2 nanoparticles with size ∼ 205 nm were synthesized via the modified sol-gel method, and then modified with poly(vinylidene fluoride) (PVDF) to form a hydrophobic surface. The SiO2 nanoparticles modified with PVDF were uniformly deposited on the outer surface of cotton fabric aided with the robust air flow force from the sprayer. The morphology and chemical structures were characterized by scanning electron microscopy, mapping, atomic force microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The results indicated that SiO2 nanoparticles were evenly deposited on the surface of cotton fibers and stable interfacial interaction occurred between SiO2 and PVDF molecular chains. The existence of SiO2 could increase the roughness of the fabric surface, which could enhance the water-repellent property of the coated fabrics. Furthermore, the water-repellent property and thermal insulation properties were evaluated via the water contact angle and thermal conductivity tests, respectively, and the results showed that 20 wt.% SiO2/PVDF fabric achieved a desirable level of contact angle, 136.6°, which was the largest water contact angle among all the samples, and the lowest thermal conductivity of 0.033 W/mK, resulting from the existence of SiO2 nanoparticles. Such a fast and simple spray-coating strategy could be widely introduced into asymmetric fabric modification, and such asymmetric fabrics with reasonable water-repellent and thermal insulating outer surfaces could act as candidates in the field of functional garments.

scholarly journals Production of Electroconductive, Superhydrphobic and Flame-Retardant Cotton Fibers via Pad-Dry-Cure Process using Silicone Rubber and Ammonium Polyphosphate

2021 ◽  
Author(s):  
Abdullah M. Al-Enizi ◽  
Asma A. Alothman ◽  
Mohd Ubaidullah ◽  
Ayman Nafady
Keyword(s):  
Flame Retardant ◽  
Silicone Rubber ◽  
Ammonium Polyphosphate ◽  
Cotton Fibers ◽  
Water Repellent ◽  
Step Method ◽  
Water Contact ◽  
Car Seat ◽  
One Step ◽  
Blend Fabric

Abstract Although pyrovatex has been widely utilized as commercial flame-retardant material, the discharge of poisonous formaldehyde is still a major concern. On the other side, fluorine-based materials have been successfully used to impart superhydrophobic textile surfaces, but they are highly expensive and extremely toxic. Based on these challenging concerns, we report a simple one-step method for the production of flame-retardant and water-repellent coating onto an electroconductive cotton-nickel (Cot-Ni) blend fabric. Firstly, the electroconductive cotton was prepared by weaving nickel strip twisted around cotton core yarns, which were then weaved with pure cotton yarns to introduce Cot-Ni blend fabric. Secondly a composite comprising ammonium polyphosphate (APP) and room-temperature vulcanized silicone rubber (RTV) was applied onto the electroconductive cotton fabrics via one-step pad-dry-cure technique. Results showed that the flame-retardant effect of cotton was enhanced due to the high binding of RTV with both APP and cotton fibers. Thus, different concentrations of APP were implemented in the composite to establish that only 100 g/L of APP with RTV presented an improved fire-retardancy. The surface of Cot-Ni fabric displayed different hierarchical morphologies relying on the concentration of APP. Moreover, RTV further enhanced the superhydrphobic nature of cotton surface. Importantly, the superhydrophobic activity was characterized by static water contact angle of the coated Cot-Ni blend. The CIE Lab colorimetric measurements of the coated Cot-Ni blend were also explored. The comfort characteristics of the coated Cot-Ni blend were assessed by measuring their air permeability and stiffness. Ultimately, these multifunctional cotton-nickel (Cot-Ni)/RTV-APP treated fabrics could be suitable for diverse applications, including firefighters’ wear, car seat mats, and grain storage containers.

scholarly journals Water modulates the lamellar structure and interlayer correlation of poly(perfluorooctyl acrylate) films: a specular and off-specular neutron scattering study

2021 ◽  
Author(s):  
Akihisa Yamamoto ◽  
Yuji Higaki ◽  
Judith Thoma ◽  
Esther Kimmle ◽  
Ryohei Ishige ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Osmotic Pressure ◽  
Correlation Length ◽  
Ethyl Acrylate ◽  
Contact Angles ◽  
Water Repellent ◽  
Water Molecules ◽  
Coating Materials ◽  
Water Contact ◽  
Vertical Correlation

AbstractComb-like polymers with pendant-like perfluorocarbon side chains self-assemble into smectic lamellae and have been extensively used as water-repellent, hydrophobic coating materials characterized by large water contact angles (θ > 120°). As poly(perfluorooctyl acrylate) films are “apparently hydrophobic” (θ > 120°), the interaction of such materials and water molecules has been largely overlooked. To unravel the molecular-level interactions between water and apparently hydrophobic polymers, specular and off-specular neutron scattering experiments were conducted at defined osmotic pressure ΠH2O. The poly{2-[(perfluorooctylethyl)carbamate]ethyl} acrylate (PFAUr-C8), which had a carbamate linker, transitioned to another lamellar phase at 89 °C. At T = 25 °C; the lamellar periodicity of PFAUr-C8 slightly increased with decreasing osmotic pressure, while the vertical correlation length increased. However, the poly[(perfluorooctyl)ethyl] acrylate (PFA-C8) that did not contain a carbamate linker directly transitioned to a disordered phase at 84 °C. The lamellar periodicity of PFA-C8 was largely independent of the osmotic pressure, suggesting that PFA-C8 was poorly hydrated. Remarkably, the vertical correlation length decreased with decreasing osmotic pressure. Because hydration facilitated by the linker modulated the smectic lamellae of the poly(perfluoroalkyl acrylate), water molecules could be used to optimize the self-assembly of apparently hydrophobic liquid crystalline polymers.

Optical and water-repellent characteristics of an anti-reflection protection layer for perovskite solar cells fabricated in ambient air

Energy ◽  
2020 ◽  
Vol 210 ◽  
pp. 118582
Author(s):  
Dong In Kim ◽  
Ji Won Lee ◽  
Rak Hyun Jeong ◽  
Ju Won Yang ◽  
Seong Park ◽  
...  
Keyword(s):  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Ambient Air ◽  
Water Repellent ◽  
Protection Layer

scholarly journals Superhydrophobic organosilicon-based coating system by a novel ultravoilet-curable method

2017 ◽  
Vol 7 ◽  
pp. 184798041770279 ◽  
Author(s):  
Baojiang Liu ◽  
Taizhou Tian ◽  
Jinlong Yao ◽  
Changgen Huang ◽  
Wenjun Tang ◽  
...  
Keyword(s):  
Contact Angle ◽  
Surface Energy ◽  
Silica Nanoparticles ◽  
Water Contact Angle ◽  
Cotton Fabric ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Water Repellent ◽  
Step Method ◽  
Water Contact

A robust superhydrophobic organosilica sol-gel-based coating on a cotton fabric substrate was successfully fabricated via a cost-effective one-step method. The coating was prepared by modification of silica nanoparticles with siloxane having long alkyl chain that allow to reduce surface energy. The coating on cotton fabric exhibited water contact angle of 151.6°. The surface morphology was evaluated by scanning electron microscopy, and surface chemical composition was measured with X-ray photoelectron spectroscopy. Results showed the enhanced superhydrophobicity that was attributed to the synergistic effect of roughness created by the random distribution of silica nanoparticles and the low surface energy imparted of long-chain alkane siloxane. In addition, the coating also showed excellent durability against washing treatments. Even after washed for 30 times, the specimen still had a water contact angle of 130°, indicating an obvious water-repellent property. With this outstanding property, the robust superhydrophobic coating exhibited a prospective application in textiles and plastics.

scholarly journals A Coaxial Dielectric Barrier Discharge Reactor for Treatment of Winter Wheat Seeds

2020 ◽  
Vol 10 (20) ◽  
pp. 7133
Author(s):  
Thalita M. C. Nishime ◽  
Nicola Wannicke ◽  
Stefan Horn ◽  
Klaus-Dieter Weltmann ◽  
Henrike Brust
Keyword(s):  
Winter Wheat ◽  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Ambient Air ◽  
Water Contact ◽  
Dielectric Barrier ◽  
Argon Discharge ◽  
Agricultural Applications ◽  
A Minor ◽  
Wheat Seeds

Non-thermal atmospheric pressure plasmas have been recently explored for their potential usage in agricultural applications as an interesting alternative solution for a potential increase in food production with a minor impact on the ecosystem. However, the adjustment and optimization of plasma sources for agricultural applications in general is an important study that is commonly overlooked. Thus, in the present work, a dielectric barrier discharge (DBD) reactor with coaxial geometry designed for the direct treatment of seeds is presented and investigated. To ensure reproducible and homogeneous treatment results, the reactor mechanically shakes the seeds during treatment, and ambient air is admixed while the discharge runs. The DBD, operating with argon and helium, produces two different chemically active states of the system for seed modification. The temperature evolution was monitored to guarantee a safe manipulation of seeds, whereas a physiological temperature was assured by controlling the exposure time. Both treatments led to a remarkable increase in wettability and acceleration in germination. The present study showed faster germination acceleration (60% faster after 24 h) and a lower water contact angle (WCA) (82% reduction) for winter wheat seeds by using the described argon discharge (with air impurities). Furthermore, the treatment can be easily optimized by adjusting the electrical parameters.

Synthesis and Characterization of ZnO-SiO2/Epoxy Nanocomposite Coating by Sol-Gel Process

2012 ◽  
Vol 16 ◽  
pp. 1-7
Author(s):  
Nazanin Farhadyar ◽  
Mirabdullah Seyed Sadjadi
Keyword(s):  
Polyethylene Glycol ◽  
Sol Gel ◽  
Nanocomposite Coating ◽  
Contact Angles ◽  
Hybrid Coatings ◽  
Coating Film ◽  
Water Contact ◽  
Unit Form ◽  
Hybrid Solution ◽  
Sol Gel Process

In this paper, we report preparation of hydrophilic hybrid nanocomposite coatings on glass substrates using Zinc acetate solutions based on 3-glycidoxypropyltrimethoxysilane (GPTMS), epoxy resin, aromatic amine (HY850), polyethylene glycol (PEG) and surfactant (polyoxyethylene(4)laurylether) by the sol-gel process. Furthermore, the effects of PEG addition to the precursor solutions on the hydrophilic property and microstructure of the resultant coating film were studied. The hydrophilic behavior study of the synthesized hybrid was performed by adding different amounts of polyethylene glycol precursor to the hybrid solution. Experimental results show that, among different amounts of PEGs, the best results are obtained by addition of PEGs (400) to the hybrid solution which can decrease the water contact angles down to 16 and using surfactant down to 0, and increase the free surface energy. Coated glass exhibits a higher strength than uncoated glass. Attenuated total reflectance infrared spectroscopic (ATR-IR) technique was used to characterize the structure of the hybrid films. The chemical structure of obtained network affects morphology of the coating. The morphology of the hybrid coatings was examined by transmission electron microscopy (TEM). The hybrid systems have a unit form structure and the inorganic phases were in the nanosize scale,

Electrothermal Properties of Porous Ceramic Fiber Media Containing Carbon Materials

2007 ◽  
Vol 7 (11) ◽  
pp. 3776-3779
Author(s):  
Sung Park ◽  
Young Pil Kwon ◽  
Hyuck Chon Kwon ◽  
Ju-Hyeon Lee ◽  
Hae-Weon Lee ◽  
...  
Keyword(s):  
Water Vapor ◽  
Carbon Materials ◽  
Porous Ceramic ◽  
Ambient Air ◽  
Ceramic Fiber ◽  
Regeneration System ◽  
Sample Weight ◽  
Experimental Apparatus ◽  
Electrothermal Desorption

Electrically regenerable porous ceramic fiber media containing nanoporous carbon from 2.5% to 19.2% have been prepared for adsorption/regeneration system. An experimental apparatus was built for in situ measurement of the sample weight during adsorption and electrothermal desorption of gaseous adsorbates. Adsorption and electrothermal desorption behavior of gaseous adsorbates on carbon contained porous ceramic fiber media was explained by physical and electrothermal properties of these materials measured in this work. In situ thermal desorption and adsorption experiments showthat a considerable amount of water vapor is adsorbed on the carbon contained media exposed to ambient air.

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