Superhydrophobic surfaces have significant potential for applications in various fields, including self-cleaning, anti-icing, and water/oil separation. However, fabricating a superhydrophobic coating that is simultaneously transparent and durable has remained a challenge due to the inherent trade-off among these three properties. In this study, we introduce a novel approach to creating a superhydrophobic and highly transparent surface with self-generated multi-scale roughness, eliminating the need for employing nanoparticles of varying sizes. Our approach revolves around developing an inorganic resin using SiO2 nanoparticles and small silica oligomers, synthesized through the sol -gel method. Subsequently, this resin is applied to the surface via spin-coating. Under specific conditions, an inorganic polymerization of TCMS occurs on the surface, leading to the formation of nanofibers and larger nanoparticles in conjunction with the initially deposited silica nanoparticles. This process enables the creation of a surface with multi-scale roughness. We investigate the influence of nanoparticle concentration, functionalization duration, and reaction temperature on surface properties. Our findings reveal that a concentration of 7 % SiO2 nanoparticles, combined with a 4-hour TCMS surface functionalization at 3 degrees C, yields the optimal conditions for fabricating a surface that combines exceptional superhydrophobicity, transparency, and durability. The resulting surface exhibits a remarkable contact angle of 160.8 degrees, a sliding angle of 1 degrees, and an 85 % transmittance rate. Moreover, the coating demonstrates impressive resistance to abrasion for up to 30 cycles and can withstand temperatures as high as 250 degrees C. Additionally, the coating shows enhanced protection against UV radiation for up to 40 h and improved resistance to sand abrasion for up to 30 s, enduring bombardment pressures of up to 6 bars. We also conduct tests on the coating for self-cleaning and anti-icing properties, demonstrating excellent performance.

This study focuses on creating a superhydrophobic, durable, and exceptionally transparent coating with dual-scale roughness by naturally formed raspberry-like particles. This approach facilitates the management of surface roughness at both single and dual scales through variations in surface functionalization temperature. We illustrated that adjusting the temperature of organosilanes functionalization on the surface allows for various reactions, such as the direct grafting of metallic precursors or their polymerization on the surface, resulting in the formation of large raspberry-like particles. We investigated the impact of nanoparticle concentration, functionalization duration, and reaction temperature on surface properties. Our results reveal that a concentration of 1.5 % SiO2 nanoparticles, combined with surface functionalization using TCMS for 4 h at 3 degrees C, provides the optimal conditions for creating a surface that combines superhydrophobicity, transparency, and acceptable durability. The resulting surface exhibits an impressive contact angle of 158.9 degrees, a sliding angle of 2 degrees, and a transmittance rate of 82 %. Furthermore, the coating demonstrates remarkable resistance to abrasion for up to 35 cycles and can withstand temperatures up to 280 degrees C. It also offers enhanced protection against UV radiation for 50 h and improved resistance to sand abrasion for up to 30 s, enduring bombardment pressures of up to 6 bars. Moreover, the coating presents several advantages in terms of surface cleaning.

Over the last decade, superhydrophobic surfaces with their new functional and structural properties have attracted a lot of interest both in the scientific research environment and in the industrial environment because of their potential to be applied in several fields, including anticorrosion, water/oil separation, ice repellency, and above all self-cleaning. This review, which should be of interest to students, researchers, and also industries focused on the chemistry of coatings, has been made with the aim of citing, explaining, and comparing in detail the structural and functional properties, the formulation techniques, the advantages, and the inconveniences of the majority of materials most used until now, and on the other hand to meet all our needs to facilitate the choice of materials for the preparation of superhydrophobic coatings according to the desired properties. This review provides a detailed analysis of recent advances in the preparation of superhydrophobic surfaces using polymeric coatings. In a significant way, the theoretical principles for the manufacturing of this type of surface have been explained, and the factors impacting the surface superhydrophobicity have been proposed. Also, an in-depth examination of the preparation approaches is categorized according to types of polymers such as polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polystyrene (PS), polyvinylidene fluoride (PVDF), polyurethane (PU), epoxy, and other polymers. Finally, the applications and challenges related to the applicability of this type of coating in everyday life are highlighted.

The utilization of resins combined with nanoparticles represents the prevailing method for fabricating superhydrophobic fabrics.

Superhydrophobic transparent coatings have recently gained significant attention in the solar energy field due to their ease of preparation, low cost, self-cleaning process, and high effectiveness in reducing dust adhesion to the surface. However, very few journals have addressed the application of self-cleaning coatings for the solar energy field due to its complexity. The transparency and the roughness responsible for the self-cleaning feature are two contradictory parameters; Increasing one parameter strongly implies a decrease in the other, Moreover, the durability of the coatings is also considered as an essential parameter for their industrial-scale acceptance, as solar panels are exposed to highly aggressive environments. Therefore, studying superhydrophobic coatings oriented for solar applications can be challenging. Most reviews reported in the literature provided limited in-formation on the choice of materials, deposition techniques, and synthesis protocols of transparent and super -hydrophobic coatings.Several reviews have addressed the topic of superhydrophobic coatings, which have various applications such as water/oil separation, anti-ice, anti-biofouling, self-cleaning and more. However, there are not many reviews that specifically focus on the development of superhydrophobic coatings for solar applications. This is mainly due to the transparency constraint required for the solar applications, making this topic particularly challenging. In the past five years, only five reviews have been published on this subject.In this review, we discuss in detail the impact of solar panel dust accumulation and its impact on their effi-ciency. Then, we discuss the principle of superhydrophobicity and self-cleaning as well as the principle of transparent coatings.

Accelerated aging experiments on solar reflectors allow for a more accurate prediction of the materials’ lifespan in a shorter period of time comparing to a study on real-Concentrated solar power (CSP) sites. Accelerated aging tests help to identify which degradations are most likely to occur under the application conditions by assessing the component’s sensitivity to various stress factors. To meet the needs of manufacturers in terms of accelerated testing, accelerated aging standards must be developed in most applications. Therefore, research and experiments must be conducted to determine appropriate techniques and therefore contribute to the standardization process. CSP is a field that entails a lot of work. The solar mirrors aging standards are still subject of research in the CSP field. They’ve all been developed or altered for use in other fields like photovoltaics. However, the outcomes of these aging tests are not always accurate or representative. In addition, the development of new materials like antisoiling coatings make the standardization process more challenging. This work aims to highlight the interest of combining accelerated erosion with other stress factors in order to get more representative results that can contribute to the standardization protocols of accelerated aging tests in the CSP for coated and uncoated solar reflectors.

Concentrated Solar Power (CSP) technology has known a huge evolution in the last decades. Reflector is one of the most strategic components in CSP plant and soiling is one of the most deleterious parameters that should deeply understood during the choice of the plant localization. The main aim of this analysis is to evaluate the impact of soiling on reflectors' reflectance in a mountain climate as Morocco is launching a new CSP plant in Midelt region (Middle Atlas mountain). Through this analysis, it is shown that correlation of climate parameters like precipitations and wind is the key to enhance the understanding of the behavior of soiling in a mountain region. Up to 57% reflectance loss is recorded during summer periods while not less than 10% reflectance is registered during all periods of analysis.

The electrical propertiesElectrical Properties of multiwalled carbon nanotubesMultiwalled Carbon Nanotube (MWCNT) based nanocompositesNanocomposites were experimentally investigated in the frequency range between 100 Hz and 1 MHz and temperature between 240 and 380 K. Two types of dielectricMatrices matricesEpoxy (Epoxy and Polyester) werePolyester used to produce two series of nanocompositesNanocomposites (Polyester-MWCNT and Epoxy-MWCNT) with different concentrations of MWCNTMultiwalled Carbon Nanotube. The obtained temperature dependence of electrical propertiesElectrical Properties of the various samples was compared and explained. Results show that the PolyesterPolyester-MWCNT nanocomposites present a lower percolation thresholdPercolation Threshold than the EpoxyEpoxy-MWCNT nanocomposites. An important thermoelectric phenomenon of transition was found in these two nanocompositesNanocomposites, above the percolation thresholdPercolation Threshold, which is the positive temperature coefficient in the resistivity effect. Moreover, the results showed that PolyesterPolyester-MWCNTMultiwalled Carbon Nanotube nanocompositesNanocomposites exhibit the maximum positive temperature coefficientPositive Temperature Coefficient intensity.

In nanofluidNanofluid composites, competing interactions, interplay and proximity effects at the interface between the different constituents often lead to interesting physical propertiesChemico-Physical Properties, sometimes to novel effects and to new functionalities. In this paper, we focus our interest on the electrical and dielectric propertiesDielectric Properties of the graphene oxide (GO)/water nanofluidNanofluid composite and on their modeling. These properties are reported in the frequency range 1‒1 MHz and in the temperature range from 295 to 309 K. The temperature dependence of the DC electrical conductivity shows a typical negative temperature coefficient in resistivity (NTCR) effect of this material. The mechanism responsible for the change in resistivity is probably predominantly tunneling, wherein the GO particles are not in physical contact and the electrons tunnel through the water gap between them. The DC electrical conductivity obeys an Arrhenius law below and above a critical temperature; that allows us to calculate both activation energies. Moreover, the dielectric responseDielectric Response was analyzed using complex permittivityComplex Permittivity formalism. A relaxation phenomenonRelaxation Phenomenon is induced in the nanofluidNanofluid suggesting that the presence of the GO particles greatly affects the dielectric propertiesDielectric Properties of the water due to the polarization phenomenon created by them. The Havriliak–Negami model was used to fit the experimental results.

Poster presented at the Fifth International Symposium on Dielectric Materials and Applications, ISyDMA’5, 15-17 april 2020 (virtual meeting), organised by the Faculty of Science Semlalia Cadi Ayyad University, Morocco.

Corrosion is among the most observed phenomena that threaten the profitability of concentrated solar thermal power plants and constitutes a real risk factor for metallic materials. Solar reflectors are between the impacted materials by corrosion because they are composed of metallic reflective layers that can easily be oxidized in air. To avoid this, paint systems could be applied in the back of the reflective layers as a barrier, that prevents the diffusion of corrosive elements to the metal layer. Metallic structures that support those reflectors can also be easily corroded and are replaced with composite structures that are not affected by corrosion. However, the durability of the paint protection systems and the composite structures must be inspected to ensure their effectiveness in protecting solar mirrors against corrosion, since they are found in sites that are often characterized by arid conditions, which affects corrosion protection solutions. This work is devoted to study the corrosion aspects and the parameters that affect the resistance of the protection systems of glass solar mirrors and solar mirrors fixed on composite structures by the use of a real outdoor exposure facility on a coastal site. The results show the important role of the paint coating layers number on the protection against corrosion. Also, the role of edge protection and shape were highlighted. Solar mirrors fixed on composite structures show a weak resistance because of the degradation of the fixing glue which creates areas of retention of salts and moisture that cause an aggressive corrosion of the metal layers.

Morocco is a country which enjoys an important potential of sunshine in many of its regions. MASEN (Moroccan Agency for Sustainable ENergy) is aiming to achieve the Kingdom objective to reach 52% energy needs through renewable energy by 2030. In this approach, the agency is launching many plants using different technologies, and especially Photovoltaic (PV) and Concentrated Solar Power (CSP). In this paper, a study of the durability of three different PV panels in two regions is presented. The study focuses on aging and soiling of these panels in two distinguished climatic stresses. Two types of comparison are made; the first one is between the behaviors of the three different panels, while the second one is between the different sites. Influence of soiling appears to be an important factor to study and a drop of 29% in maximal power was noticed after one month outdoor exposure. The aging is also studied during around 1000 days exposure. An annual loss between 0.44% and 1.1% is recorded in one site while in the other it is between 1.8% and 5.9% for the three devices.

Solar mirrors samples are exposed in a Moroccan natural aging site where the climatic stresses could create different degradationsand failures on samples materials that consist mainly on metal corrosion, detachment of protective layers and surface erosion. The climatic parameters that cause stress are temperature, wind velocity, rain, solar irradiation and sandstorms frequency. The useful lifetime of reflectors is conditioned by the effect of these parameters on the optical performance deterioration. During the exposure period, it has been found that weather conditions had generated surface erosion as well as physical and chemical degradation of glass surfaces of tested mirrors. The intensity of both phenomena depends on the mirrors surface nature, climatic conditions and samples exposure orientations. Optical performance of mirrors decreases considerably under extreme climatic conditions and erosive environment.

Solar energy is becoming a key solution to reduce the use of fossil energies for many countries which have a good amount of irradiance per year. However, good resources of irradiance are always optimal in regions with arid environment and aggressive climatic stresses. These factors are harmful for the efficiency of the solar systems, so they should he considered during the choice of the location and of the type of technology to use. In the present paper, a study of the degradation of different materials dedicated to solar energy is presented. Two types of reflectors for the Concentrated Solar Power (CSP) are tested in the same real conditions of exposure. One type presents higher loss in term of reflectance while the second type backside paint is less resistant to the climate which could accelerate corrosion through the metal layer. Three photovoltaic (PV) panels are exposed to real conditions in two different climates. The following up of their electrical characteristics during similar to 700 days has shown that the degradation of output power could reach 21%. In addition, the study showed that one TV panel is not behoving in the same way in the two different climate conditions.

ABSTRACTThe purpose of this study is to identify the relationship between the electrical and structural characteristics of multiwalled carbon nanotubes dispersed into the polymer matrix of a resin. In a first step, the composites were characterized by small‐angle neutron scattering, which provide information about the bulk dispersion of nanotubes in the matrix and form three‐dimensional networks with a surface fractal behavior. In the second step, a dielectric and electrical study was carried out in the frequency range between 1 Hz and 10 MHz at room temperature. We have found that the electric and dielectric behavior of these composites can be described by Jonscher's universal dielectric response. We show that the critical exponents describing the concentration dependence of the conductivity and the dielectric constant, obtained in the vicinity of the percolation threshold, are in good agreement with the theoretical values. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44514.