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10 pages, 1724 KiB

Open AccessArticle

High-Resolution Nanotransfer Printing of Porous Crossbar Array Using Patterned Metal Molds by Extreme-Pressure Imprint Lithography

by Tae Wan Park, Young Lim Kang, Yu Na Kim and Woon Ik Park

Nanomaterials 2023, 13(16), 2335; https://doi.org/10.3390/nano13162335 - 14 Aug 2023

Cited by 1 | Viewed by 975

Abstract

High-resolution nanotransfer printing (nTP) technologies have attracted a tremendous amount of attention due to their excellent patternability, high productivity, and cost-effectiveness. However, there is still a need to develop low-cost mold manufacturing methods, because most nTP techniques generally require the use of patterned [...] Read more.

High-resolution nanotransfer printing (nTP) technologies have attracted a tremendous amount of attention due to their excellent patternability, high productivity, and cost-effectiveness. However, there is still a need to develop low-cost mold manufacturing methods, because most nTP techniques generally require the use of patterned molds fabricated by high-cost lithography technology. Here, we introduce a novel nTP strategy that uses imprinted metal molds to serve as an alternative to a Si stamp in the transfer printing process. We present a method by which to fabricate rigid surface-patterned metallic molds (Zn, Al, and Ni) based on the process of direct extreme-pressure imprint lithography (EPIL). We also demonstrate the nanoscale pattern formation of functional materials, in this case Au, TiO₂, and GST, onto diverse surfaces of SiO₂/Si, polished metal, and slippery glass by the versatile nTP method using the imprinted metallic molds with nanopatterns. Furthermore, we show the patterning results of nanoporous crossbar arrays on colorless polyimide (CPI) by a repeated nTP process. We expect that this combined nanopatterning method of EPIL and nTP processes will be extendable to the fabrication of various nanodevices with complex circuits based on micro/nanostructures. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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11 pages, 2130 KiB

Open AccessArticle

Microsecond All-Optical Modulation by Biofunctionalized Porous Silicon Microcavity

by Dániel Petrovszki, Sándor Valkai, Lóránd Kelemen, László Nagy, Vivechana Agarwal, Szilvia Krekic, László Zimányi and András Dér

Nanomaterials 2023, 13(14), 2070; https://doi.org/10.3390/nano13142070 - 14 Jul 2023

Cited by 1 | Viewed by 910

Abstract

We successfully created a composite photonic structure out of porous silicon (PSi) microcavities doped by the photochromic protein, photoactive yellow protein (PYP). Massive incorporation of the protein molecules into the pores was substantiated by a 30 nm shift of the resonance dip upon [...] Read more.

We successfully created a composite photonic structure out of porous silicon (PSi) microcavities doped by the photochromic protein, photoactive yellow protein (PYP). Massive incorporation of the protein molecules into the pores was substantiated by a 30 nm shift of the resonance dip upon functionalization, and light-induced reflectance changes of the device due to the protein photocycle were recorded. Model calculations for the photonic properties of the device were consistent with earlier results on the nonlinear optical properties of the protein, whose degree of incorporation into the PSi structure was also estimated. The successful proof-of-concept results are discussed in light of possible practical applications in the future. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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13 pages, 2221 KiB

Open AccessArticle

Multifunctional Edible Oil-Impregnated Nanoporous Oxide Layer on AISI 304 Stainless Steel

by Kichang Bae, Minju Kang, Yeji Shin, Eunyoung Choi, Young-Mog Kim and Junghoon Lee

Nanomaterials 2023, 13(5), 807; https://doi.org/10.3390/nano13050807 - 22 Feb 2023

Cited by 2 | Viewed by 1331

Abstract

Slippery liquid-infused porous surface (SLIPS) realized on commercial materials provides various functionalities, such as corrosion resistance, condensation heat transfer, anti-fouling, de/anti-icing, and self-cleaning. In particular, perfluorinated lubricants infused in fluorocarbon-coated porous structures have showed exceptional performances with durability; however, they caused several issues [...] Read more.

Slippery liquid-infused porous surface (SLIPS) realized on commercial materials provides various functionalities, such as corrosion resistance, condensation heat transfer, anti-fouling, de/anti-icing, and self-cleaning. In particular, perfluorinated lubricants infused in fluorocarbon-coated porous structures have showed exceptional performances with durability; however, they caused several issues in safety, due to their difficulty in degradation and bio-accumulation. Here, we introduce a new approach to create the multifunctional lubricant-impregnated surface with edible oils and fatty acid, which are also safe to human body and degradable in nature. The edible oil-impregnated anodized nanoporous stainless steel surface shows a significantly low contact angle hysteresis and sliding angle, which is similar with general surface of fluorocarbon lubricant-infused systems. The edible oil impregnated in the hydrophobic nanoporous oxide surface also inhibits the direct contact of external aqueous solution to a solid surface structure. Due to such de-wetting property caused by a lubricating effect of edible oils, the edible oil-impregnated stainless steel surface shows enhanced corrosion resistance, anti-biofouling and condensation heat transfer with reduced ice adhesion. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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14 pages, 3336 KiB

Open AccessArticle

Control of the Nanopore Architecture of Anodic Alumina via Stepwise Anodization with Voltage Modulation and Pore Widening

by Chanyoung Jeong, Jeki Jung, Keith Sheppard and Chang-Hwan Choi

Nanomaterials 2023, 13(2), 342; https://doi.org/10.3390/nano13020342 - 13 Jan 2023

Cited by 5 | Viewed by 1979

Abstract

Control of the morphology and hierarchy of the nanopore structures of anodic alumina is investigated by employing stepwise anodizing processes, alternating the two different anodizing modes, including mild anodization (MA) and hard anodization (HA), which are further mediated by a pore-widening (PW) step [...] Read more.

Control of the morphology and hierarchy of the nanopore structures of anodic alumina is investigated by employing stepwise anodizing processes, alternating the two different anodizing modes, including mild anodization (MA) and hard anodization (HA), which are further mediated by a pore-widening (PW) step in between. For the experiment, the MA and HA are applied at the anodizing voltages of 40 and 100 V, respectively, in 0.3 M oxalic acid, at 1 °C, for fixed durations (30 min for MA and 0.5 min for HA), while the intermediate PW is applied in 0.1 M phosphoric acid at 30 °C for different durations. In particular, to examine the effects of the anodizing sequence and the PW time on the morphology and hierarchy of the nanopore structures formed, the stepwise anodization is conducted in two different ways: one with no PW step, such as MA→HA and HA→MA, and the other with the timed PW in between, such as MA→PW→MA, MA→PW→HA, HA→PW→HA, and HA→PW→MA. The results show that both the sequence of the voltage-modulated anodizing modes and the application of the intermediate PW step led to unique three-dimensional morphology and hierarchy of the nanopore structures of the anodic alumina beyond the conventional two-dimensional cylindrical pore geometry. It suggests that the stepwise anodizing process regulated by the sequence of the anodizing modes and the intermediate PW step can allow the design and fabrication of various types of nanopore structures, which can broaden the applications of the nanoporous anodic alumina with greater efficacy and versatility. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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13 pages, 32224 KiB

Open AccessFeature PaperArticle

Tannic Acid as a Versatile Template for Silica Monoliths Engineering with Catalytic Gold and Silver Nanoparticles

by Irina Postnova and Yury Shchipunov

Nanomaterials 2022, 12(23), 4320; https://doi.org/10.3390/nano12234320 - 05 Dec 2022

Cited by 4 | Viewed by 1677

Abstract

Tannic acid in alkaline solutions in which sol-gel synthesis is usually performed with tetraethoxysilane is susceptible to various modifications, including formation of reactive radicals, oxidation under the action of atmospheric oxygen, self-association, and self-polymerization. Here, a precursor with ethylene glycol residues instead of [...] Read more.

Tannic acid in alkaline solutions in which sol-gel synthesis is usually performed with tetraethoxysilane is susceptible to various modifications, including formation of reactive radicals, oxidation under the action of atmospheric oxygen, self-association, and self-polymerization. Here, a precursor with ethylene glycol residues instead of ethanol was used, which made it possible to synthesize bionanocomposites of tannic acid and silica in one stage in neutral media under normal conditions without the addition of acid/alkali and organic solvents. Silica was fabricated in the form of optically transparent monoliths of various shapes with 2–4 nm pores, the radius of which well correlated with the size of a tannic acid macromolecule in a non-aggregated state. Polyphenol, which was remained in pores of silica matrix, served then as reducing agent to synthesize in situ gold and silver nanoparticles. As shown, these Au@SiO₂ and Ag@SiO₂ nanocomposites possessed localized surface plasmon resonance and high catalytic activity. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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16 pages, 4786 KiB

Open AccessArticle

Electrochemical Deposition of Ferromagnetic Ni Nanoparticles in InP Nanotemplates Fabricated by Anodic Etching Using Environmentally Friendly Electrolyte

by Călin Constantin Moise, Geanina Valentina Mihai, Liana Anicăi, Eduard V. Monaico, Veaceslav V. Ursaki, Marius Enăchescu and Ion M. Tiginyanu

Nanomaterials 2022, 12(21), 3787; https://doi.org/10.3390/nano12213787 - 27 Oct 2022

Cited by 1 | Viewed by 1160

Abstract

Porous InP templates possessing a thickness of up to 100 µm and uniformly distributed porosity were prepared by anodic etching of InP substrates exhibiting different electrical conductivities, involving an environmentally friendly electrolyte. Ni nanoparticles were successfully directly deposited by pulsed electroplating into prefabricated [...] Read more.

Porous InP templates possessing a thickness of up to 100 µm and uniformly distributed porosity were prepared by anodic etching of InP substrates exhibiting different electrical conductivities, involving an environmentally friendly electrolyte. Ni nanoparticles were successfully directly deposited by pulsed electroplating into prefabricated InP templates without any additional deposition of intermediary layers. The parameters of electrodeposition, including the pulse amplitude, pulse width and interval between pulses, were optimized to reach a uniform metal deposition covering the inner surface of the nanopores. The electrochemical dissolution of n-InP single crystals was investigated by measuring the current–voltage dependences, while the Ni-decorated n-InP templates have been characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The proposed technology is expected to be of interest for sensing and photocatalytic applications, as well as for the exploration of their plasmonic and magnetic properties. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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14 pages, 3823 KiB

Open AccessArticle

Phosphorylated Poly(vinyl alcohol) Electrospun Mats for Protective Equipment Applications

by Diana Serbezeanu, Tăchiță Vlad-Bubulac, Mihaela Dorina Onofrei, Florica Doroftei, Corneliu Hamciuc, Alina-Mirela Ipate, Alexandru Anisiei, Gabriela Lisa, Ion Anghel, Ioana-Emilia Şofran and Vasilica Popescu

Nanomaterials 2022, 12(15), 2685; https://doi.org/10.3390/nano12152685 - 04 Aug 2022

Cited by 4 | Viewed by 1381

Abstract

The development of intelligent materials for protective equipment applications is still growing, with enormous potential to improve the safety of personnel functioning in specialized professions, such as firefighters. The design and production of such materials by the chemical modification of biodegradable semisynthetic polymers, [...] Read more.

The development of intelligent materials for protective equipment applications is still growing, with enormous potential to improve the safety of personnel functioning in specialized professions, such as firefighters. The design and production of such materials by the chemical modification of biodegradable semisynthetic polymers, accompanied by modern manufacturing techniques such as electrospinning, which may increase specific properties of the targeted material, continue to attract the interest of researchers. Phosphorus-modified poly(vinyl alcohol)s have been, thus, synthesized and utilized to prepare environmentally friendly electrospun mats. Poly(vinyl alcohol)s of three different molecular weights and degrees of hydrolysis were phosphorylated by polycondensation reaction in solution in the presence of phenyl dichlorophosphate in order to enhance their flame resistance and thermal stability. The thermal behavior and the flame resistance of the resulting phosphorus-modified poly(vinyl alcohol) products were investigated by thermogravimetric analysis and by cone calorimetry at a micro scale. Based on the as-synthesized phosphorus-modified poly(vinyl alcohol)s, electrospun mats were successfully fabricated by the electrospinning process. Rheology studies were performed to establish the optimal conditions of the electrospinning process, and scanning electron microscopy investigations were undertaken to observe the morphology of the phosphorus-modified poly(vinyl alcohol) electrospun mats. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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10 pages, 2730 KiB

Open AccessEditor’s ChoiceArticle

Thermal Radiative Copper Oxide Layer for Enhancing Heat Dissipation of Metal Surface

by Junghyun Park, Donghyun Kim, Hyunsik Kim, Junghoon Lee and Wonsub Chung

Nanomaterials 2021, 11(11), 2819; https://doi.org/10.3390/nano11112819 - 24 Oct 2021

Cited by 6 | Viewed by 2514

Abstract

The heat dissipation of a metal heat sink for passive cooling can be enhanced by surface modifications to increase its thermal emissivity, which is reflected by a darker surface appearance. In this study, copper electrodeposition followed by heat treatment was applied to a [...] Read more.

The heat dissipation of a metal heat sink for passive cooling can be enhanced by surface modifications to increase its thermal emissivity, which is reflected by a darker surface appearance. In this study, copper electrodeposition followed by heat treatment was applied to a copper substrate. The heat treatment formed a nanoporous oxide layer containing CuO and Cu₂O, which has a dark blackish color and therefore increased the thermal emissivity of the surface. The heat dissipation performance was evaluated using the sample as a heat sink for an LED module. The surface-treated copper heat sink with a high thermal emissivity oxide layer enhanced the heat dissipation of the LED module and allowed it to be operated at a lower temperature. With an increase in the heat treatment, the thermal emissivity increases to 0.865, but the thermal diffusivity is lower than the copper substrate by ~12%. These results indicate that the oxide layer is a thermal barrier for heat transfer, thus optimization between the oxide thickness and thermal emissivity is required by evaluating heat dissipation performance in operating conditions. In this study, an oxide layer with an emissivity of 0.857 and ~5% lower thermal diffusivity than the copper substrate showed the lowest LED operating temperature. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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Review

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51 pages, 8827 KiB

Open AccessFeature PaperReview

Recent Progress in the Fabrication and Optical Properties of Nanoporous Anodic Alumina

by Khoobaram S. Choudhari, Chang-Hwan Choi, Santhosh Chidangil and Sajan D. George

Nanomaterials 2022, 12(3), 444; https://doi.org/10.3390/nano12030444 - 28 Jan 2022

Cited by 15 | Viewed by 3517

Abstract

The fabrication of a thick oxide layer onto an aluminum surface via anodization has been a subject of intense research activity for more than a century, largely due to protective and decorative applications. The capability to create well-defined pores via a cost-effective electrochemical [...] Read more.

The fabrication of a thick oxide layer onto an aluminum surface via anodization has been a subject of intense research activity for more than a century, largely due to protective and decorative applications. The capability to create well-defined pores via a cost-effective electrochemical oxidation technique onto the surface has made a major renaissance in the field, as the porous surfaces exhibit remarkably different properties compared to a bulk oxide layer. Amongst the various nanoporous structures being investigated, nanoporous anodic alumina (NAA) with well-organized and highly ordered hexagonal honeycomb-like pores has emerged as the most popular nanomaterial due to its wide range of applications, ranging from corrosion resistance to bacterial repelling surfaces. As compared to conventional nanostructure fabrication, the electrochemical anodization route of NAA with well-controlled pore parameters offers an economical route for fabricating nanoscale materials. The review comprehensively reflects the progress made in the fabrication route of NAA to obtain the material with desired pore properties, with a special emphasis on self-organization and pore growth kinetics. Detailed accounts of the various conditions that can play an important role in pore growth kinetics and pore parameters are presented. Further, recent developments in the field of controlling optical properties of NAA are discussed. A critical outlook on the future trends of the fabrication of NAA and its optical properties on the emerging nanomaterials, sensors, and devices are also outlined. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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