Topic Editors

Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, via Mancinelli 7, 20131 Milan, Italy
Department of Materials Science, University of Milano Bicocca, Milan, Italy
Department of Materials Science, University of Milano-Bicocca, 20125 Milan, Italy
Institute of Condensed Matter Chemistry and Technologies for Energy, National Research Council, CNR-ICMATE, Via De Marini 6, 16149 Genova, Italy

Advanced Self-Cleaning Surfaces

Abstract submission deadline
31 July 2023
Manuscript submission deadline
30 September 2023
Viewed by
10045

Topic Information

Dear Colleagues,

We would like to draw your attention to a new interdisciplinary topic dedicated to advanced self-cleaning surfaces. Self-cleaning effects can be utilized in a variety of applications, from cleaner building surfaces to anti-fogging mirrors, low-drag ship hulls, anti-bacterial and anti-viral surfaces, and food container draining. The methods used to achieve self-cleaning are diverse, and all rely on tuning wettability, meaning that either the surface chemistry or morphology, or both, are modified to make surfaces superhydrophilic, superhydrophobic, amphiphilic, or oleophobic. Wettability changes can be permanent or induced by an external stimulus, as in the case of photoinduced phenomena. Nature is often the key: most modifications currently adopted are actually bioinspired—e.g., by lotus leaves, shark skin, or mosquito eyes, to name a few. This interdisciplinary topic aims to collect all possible approaches to self-cleaning, including theoretical approaches as well as small-scale laboratory experiments and material validation in relevant environments from the nanometer to meter scale. Joining all aspects of such a faceted phenomenon in a single collection of articles will help the scientific community involved in this field to improve collaboration among diverse disciplines and promote novel insights across interdisciplinary research fields. To take into account its peculiar interdisciplinary character, this article collection will be published in five different journals: Coatings, Materials, Membranes, Nanomaterials, and Surfaces.

Prof. Dr. Maria Vittoria Diamanti
Prof. Dr. Massimiliano D'Arienzo
Dr. Carlo Antonini
Dr. Michele Ferrari
Topic Editors

Keywords

  • self-cleaning
  • superhydrophilic
  • superhydrophobic
  • amphiphilic
  • oleophobic
  • bioinspired
  • nanostructured surfaces
  • wetting
  • wettability
  • photoactivity
  • antibacterial
  • antiviral
  • numerical simulations
  • experimental tests
  • theoretical approach
  • surface characterization
  • chemical/physical surface modifications

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Coatings
coatings
3.236 3.9 2011 13.5 Days 2200 CHF Submit
Materials
materials
3.748 4.7 2008 13.9 Days 2300 CHF Submit
Membranes
membranes
4.562 3.7 2011 12.1 Days 2200 CHF Submit
Nanomaterials
nanomaterials
5.719 6.6 2011 12.7 Days 2600 CHF Submit
Surfaces
surfaces
- - 2018 26.6 Days 1400 CHF Submit

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Published Papers (8 papers)

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Article
Novel Engineered Carbon Cloth-Based Self-Cleaning Membrane for High-Efficiency Oil–Water Separation
Nanomaterials 2023, 13(4), 624; https://doi.org/10.3390/nano13040624 - 04 Feb 2023
Viewed by 454
Abstract
A novel engineered carbon cloth (CC)-based self-cleaning membrane containing a Cu:TiO2 and Ag coating has been created via hydrothermal and light deposition methods. The engineered membrane with chrysanthemum morphology has superhydrophilic and underwater superhydrophobic performance. The cooperativity strategy of Cu doping and [...] Read more.
A novel engineered carbon cloth (CC)-based self-cleaning membrane containing a Cu:TiO2 and Ag coating has been created via hydrothermal and light deposition methods. The engineered membrane with chrysanthemum morphology has superhydrophilic and underwater superhydrophobic performance. The cooperativity strategy of Cu doping and Ag coating to the TiO2 is found to be critical for engineering the separation efficiency and self-cleaning skill of the CC-based membrane under visible light due to the modulated bandgap structure and surface plasmon resonance. The CC-based membrane has excellent oil–water separation performance when Cu is fixed at 2.5 wt% and the Ag coating reaches a certain amount of 0.003 mol/L AgNO3. The contact angle of underwater oil and the separation efficiency are 156° and 99.76%, respectively. Furthermore, the membrane has such an outstanding self-cleaning ability that the above performance can be nearly completely restored after 30 min of visible light irradiation, and the separation efficiency can still reach 99.65% after 100 cycles. Notably, the membrane with exceptional wear resistance and durability can work in various oil–water mixtures and harsh environments, indicating its potential as a new platform of the industrial-level available membrane in dealing with oily wastewater. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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Article
Benchmarking the Photocatalytic Self-Cleaning Activity of Industrial and Experimental Materials with ISO 27448:2009
Materials 2023, 16(3), 1119; https://doi.org/10.3390/ma16031119 - 28 Jan 2023
Viewed by 532
Abstract
Various industrial surface materials are tested for their photocatalytic self-cleaning activity by performing the ISO 27448:2009 method. The samples are pre-activated by UV irradiation, fouled with oleic acid and irradiated by UV light. The degradation of oleic acid over time is monitored by [...] Read more.
Various industrial surface materials are tested for their photocatalytic self-cleaning activity by performing the ISO 27448:2009 method. The samples are pre-activated by UV irradiation, fouled with oleic acid and irradiated by UV light. The degradation of oleic acid over time is monitored by taking water contact angle measurements using a contact angle goniometer. The foulant, oleic acid, is an organic acid that makes the surface more hydrophobic. The water contact angle will thus decrease over time as the photocatalytic material degrades the oleic acid. In this study, we argue that the use of this method is strongly limited to specific types of surface materials, i.e., only those that are hydrophilic and smooth in nature. For more hydrophobic materials, the difference in the water contact angles of a clean surface and a fouled surface is not measurable. Therefore, the photocatalytic self-cleaning activity cannot be established experimentally. Another type of material that cannot be tested by this standard are rough surfaces. For rough surfaces, the water contact angle cannot be measured accurately using a contact angle goniometer as prescribed by the standard. Because of these limitations, many potentially interesting industrial substrates cannot be evaluated. Smooth samples that were treated with an in-house developed hydrophilic titania thin film (PCT/EP2018/079983) showed a great photocatalytic self-cleaning performance according to the ISO standard. Apart from discussing the pros and cons of the current ISO standard, we also stress how to carefully interpret the results and suggest alternative testing solutions. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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Article
Fabrication of Superhydrophobic Composite Membranes with Honeycomb Porous Structure for Oil/Water Separation
Coatings 2022, 12(11), 1698; https://doi.org/10.3390/coatings12111698 - 08 Nov 2022
Cited by 2 | Viewed by 646
Abstract
Due to the low separation efficiency and poor separation stability, traditional polymer filtration membranes are prone to be polluted and difficult to reuse in harsh environments. Herein, we reported a nanofibrous membrane with a honeycomb–like pore structure, which was prepared by electrospinning and [...] Read more.
Due to the low separation efficiency and poor separation stability, traditional polymer filtration membranes are prone to be polluted and difficult to reuse in harsh environments. Herein, we reported a nanofibrous membrane with a honeycomb–like pore structure, which was prepared by electrospinning and electrospraying. During the electrospraying process, the addition of polydimethylsiloxane and fumed SiO2 formed pores by electrostatic repulsion between ions, thereby increasing the membrane flux, subsequently reducing the surface energy, and increasing the surface roughness. The results show that when the content of SiO2 reaches 1.5 wt%, an ultra–high hydrophobic angle (162.1° ± 0.7°) was reached. After 10 cycles of oil–water separation tests of the composite membrane, the oil–water separation flux and separation efficiency was still as high as 5400 L m−2 h−1 and 99.4%, and the membrane maintained excellent self–cleaning ability. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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Article
Controlling Morphology and Wettability of Intrinsically Superhydrophobic Copper-Based Surfaces by Electrodeposition
Coatings 2022, 12(9), 1260; https://doi.org/10.3390/coatings12091260 - 29 Aug 2022
Cited by 1 | Viewed by 1033
Abstract
Electrodeposition is an effective and scalable method to grow desired structures on solid surfaces, for example, to impart superhydrophobicity. Specifically, copper microcrystals can be grown using electrodeposition by controlling deposition parameters such as the electrolyte and its acidity, the bath temperature, and the [...] Read more.
Electrodeposition is an effective and scalable method to grow desired structures on solid surfaces, for example, to impart superhydrophobicity. Specifically, copper microcrystals can be grown using electrodeposition by controlling deposition parameters such as the electrolyte and its acidity, the bath temperature, and the potential modulation. The aim of the present work is the fabrication of superhydrophobic copper-based surfaces by electrodeposition, investigating both surface properties and assessing durability under conditions relevant to real applications. Accordingly, copper-based layers were fabricated on Au/Si(100) from Cu(BF4)2 precursor by electrodeposition, using cyclic voltammetry and square-pulse voltage approaches. By increasing the bath temperature from 22 °C to 60 °C, the growth of various structures, including micrometric polyhedral crystals and hierarchical structures, ranging from small grains to pine-needle-like dendrite leaves, has been demonstrated. Without any further physical and/or chemical modification, samples fabricated with square-pulse voltage at 60 °C are superhydrophobic, with a contact angle of 160° and a sliding angle of 15°. In addition, samples fabricated from fluoroborate precursor are carefully compared to those fabricated from sulphate precursor to compare chemical composition, surface morphology, wetting properties, and durability under UV exposure and hard abrasion. Results show that although electrodeposition from fluoroborate precursor can provide dendritic microstructures with good superhydrophobicity properties, surfaces possess lower durability and stability compared to those fabricated from the sulphate precursor. Hence, from an application point of view, fabrication of copper superhydrophobic surfaces from sulphate precursor is more recommended. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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Article
Candle Soot-Based Electrosprayed Superhydrophobic Coatings for Self-Cleaning, Anti-Corrosion and Oil/Water Separation
Materials 2022, 15(15), 5300; https://doi.org/10.3390/ma15155300 - 01 Aug 2022
Viewed by 924
Abstract
The interest in candle soot (CS)-based superhydrophobic coatings has grown rapidly in recent years. Here, a simple and low-cost process has been developed for the fabrication of CS-based superhydrophobic coatings through electrospraying of the composite cocktail solution of CS and polyvinylidene fluoride (PVDF). [...] Read more.
The interest in candle soot (CS)-based superhydrophobic coatings has grown rapidly in recent years. Here, a simple and low-cost process has been developed for the fabrication of CS-based superhydrophobic coatings through electrospraying of the composite cocktail solution of CS and polyvinylidene fluoride (PVDF). Results show that the superhydrophobicity of the coating closely relates to the loading amount of CS which results in coatings with different roughnesses. Specifically, increasing the CS amount (not more than 0.4 g) normally enhances the superhydrophobicity of the coating due to higher roughness being presented in the produced microspheres. Further experiments demonstrate that the superhydrophobicity induced in the electrosprayed coating results from the synergistic effect of the cocktail solution and electrospray process, indicating the importance of the coating technique and the solution used. Versatile applications of CS-based superhydrophobic coatings including self-cleaning, anti-corrosion and oil/water separation are demonstrated. The present work provides a convenient method for the fabrication of CS-based superhydrophobic coatings, which is believed to gain great interest in the future. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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Review
A Comprehensive Review of Wetting Transition Mechanism on the Surfaces of Microstructures from Theory and Testing Methods
Materials 2022, 15(14), 4747; https://doi.org/10.3390/ma15144747 - 06 Jul 2022
Cited by 3 | Viewed by 1388
Abstract
Superhydrophobic surfaces have been widely employed in both fundamental research and industrial applications because of their self-cleaning, waterproof, and low-adhesion qualities. Maintaining the stability of the superhydrophobic state and avoiding water infiltration into the microstructure are the basis for realizing these characteristics, while [...] Read more.
Superhydrophobic surfaces have been widely employed in both fundamental research and industrial applications because of their self-cleaning, waterproof, and low-adhesion qualities. Maintaining the stability of the superhydrophobic state and avoiding water infiltration into the microstructure are the basis for realizing these characteristics, while the size, shape, and distribution of the heterogeneous microstructures affect both the static contact angle and the wetting transition mechanism. Here, we review various classical models of wettability, as well as the advanced models for the corrected static contact angle for heterogeneous surfaces, including the general roughness description, fractal theory description, re-entrant geometry description, and contact line description. Subsequently, we emphasize various wetting transition mechanisms on heterogeneous surfaces. The advanced testing strategies to investigate the wetting transition behavior will also be analyzed. In the end, future research priorities on the wetting transition mechanisms of heterogeneous surfaces are highlighted. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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Article
Virucidal and Bactericidal Filtration Media from Electrospun Polylactic Acid Nanofibres Capable of Protecting against COVID-19
Membranes 2022, 12(6), 571; https://doi.org/10.3390/membranes12060571 - 30 May 2022
Cited by 1 | Viewed by 1465
Abstract
Electrospun nanofibres excel at air filtration owing to diverse filtration mechanisms, thereby outperforming meltblown fibres. In this work, we present an electrospun polylactide acid nanofibre filter media, FilterLayrTM Eco, displaying outstanding bactericidal and virucidal properties using Manuka oil. Given the existing COVID-19 [...] Read more.
Electrospun nanofibres excel at air filtration owing to diverse filtration mechanisms, thereby outperforming meltblown fibres. In this work, we present an electrospun polylactide acid nanofibre filter media, FilterLayrTM Eco, displaying outstanding bactericidal and virucidal properties using Manuka oil. Given the existing COVID-19 pandemic, face masks are now a mandatory accessory in many countries, and at the same time, they have become a source of environmental pollution. Made by NanoLayr Ltd., FilterLayrTM Eco uses biobased renewable raw materials with products that have end-of-life options for being industrially compostable. Loaded with natural and non-toxic terpenoid from manuka oil, FilterLayr Eco can filter up to 99.9% of 0.1 µm particles and kill >99% of trapped airborne fungi, bacteria, and viruses, including SARS-CoV-2 (Delta variant). In addition, the antimicrobial activity, and the efficacy of the filter media to filtrate particles was shown to remain highly active following several washing cycles, making it a reusable and more environmentally friendly option. The new nanofibre filter media, FilterLayrTM Eco, met the particle filtration efficiency and breathability requirements of the following standards: N95 performance in accordance with NIOSH 42CFR84, level 2 performance in accordance with ASTM F2100, and level 2 filtration efficiency and level 1 breathability in accordance with ASTM F3502. These are globally recognized facemask and respirator standards. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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Article
Polypropylene Hollow-Fiber Membrane Made Using the Dissolution-Induced Pores Method
Membranes 2022, 12(4), 384; https://doi.org/10.3390/membranes12040384 - 31 Mar 2022
Viewed by 1645
Abstract
The efficient preparation of hydrophilic polypropylene membranes has always been a problem. Here, a twin-screw extruder was used to melt-blend ethylene-vinyl alcohol copolymer and polypropylene; then, hollow fibers were extrusion-molded with a spinneret and taken by a winder; after this, dimethyl sulfoxide was [...] Read more.
The efficient preparation of hydrophilic polypropylene membranes has always been a problem. Here, a twin-screw extruder was used to melt-blend ethylene-vinyl alcohol copolymer and polypropylene; then, hollow fibers were extrusion-molded with a spinneret and taken by a winder; after this, dimethyl sulfoxide was used to dissolve the ethylene-vinyl alcohol copolymer of the fiber to obtain a polypropylene hollow-fiber membrane. This procedure was used to study the effects of different contents and segment structure of ethylene-vinyl alcohol copolymer on the structure and filtration performance of the membranes; furthermore, the embedded factor and blocked factor were used to evaluate the ethylene-vinyl alcohol copolymer embedded in the matrix without dissolving and or being completely blocked in the matrix, respectively. The results show that the increase in ethylene-vinyl alcohol copolymer could reduce the embedded factor and increase the blocked factor. The increase in the polyethylene segments of ethylene-vinyl alcohol copolymer could increase both the embedded factor and blocked factor. The water permeation of the membrane reached 1300 Lm−2·h−1·bar−1 with a 100% rejection of ink (141 nm) and the elongation at break reached 188%, while the strength reached 22 MPa. The dissolution-induced pores method provides a completely viable alternative route for the preparation of polypropylene membranes. Full article
(This article belongs to the Topic Advanced Self-Cleaning Surfaces)
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