سنتز نانوکامپوزیت های پلیمری فوق آبگریز به عنوان فیلم های پوششی خود پاک شونده هوشمند Synthesis of Super-Hydrophobic Polymer Nanocomposites as a Smart Self-Cleaning Coating Films

INTRODUCTION Many types of polymers can be used for packaging food, tools, and other items. These polymers can be translated, placed on shelf storage in open air, and used in dirty places or in a vapor atmosphere (e.g., chairs in stadiums or cars). These conditions accelerate the attachment of dirty, small particles of sand or other undesirable materials to render the surface unclean and visually unappealing. Furthermore, outside windows or doors need to be cleaned daily. Therefore, it is necessary to prepare special types of polymer characteristics with self-cleaning behaviors to overcome this vital problem. Wettability is an important property of solid surfaces and is mainly determined by two factors: the surface topography and chemical composition [1–۱۲]. Super-hydrophobic (SH) surfaces [3–۹, ۱۳–۱۸], which have a contact angle (CA) larger than 1508, have attracted much attention due to their practical applications [19]. Super-hydrophobic surfaces can usually be achieved by forming hierarchical micro/ nanoscale binary structures and by chemical modification to apply materials with low surface energy to another material. The Wenzel model [1] and the Cassie-Baxter model [12] are most frequently used to account for experimental results. The Wenzel model describes wetting behavior where a liquid droplet on a rough surface is in intimate contact with surface asperities, while the Cassie model describes states where the droplet sits on a solid–air composite surface [20–۲۵]. The key difference between the two regimes is the contact angle hysteresis, with the contact angle hysteresis of the Cassie wetting regime being much lower than that of the Wenzel wetting regime. The underlying trapped air in a Cassie state can be eliminated when a pressure is applied, resulting in a transition to the Wenzel state. This is called a “metastable00 Cassie state. The contact mode depends on the way liquid drops are deposited on the surface. For example, dragging over a rough surface [26] or being impacted can lead to such a transition [27]. The impact action of a droplet on a super-hydrophobic surface has been studied by several groups [28–۳۷]. Lee and coworkers [27] confirmed that the impacting action between water droplets and the surface depends on the geometric parameters of the surface, and only certain geometries could result in a robust Cassie regime [27]. Bhushan and coworkers [29] developed a criterion in which the transition from the Cassie regime to the Wenzel regime is determined by three factors: impact velocity, geometric parameters of patterned surfaces (the length, width, and height of patterns and pitch between them), and liquid properties. Generally, the mentioned studies focus on the effect of geometric parameters of surfaces on the wetting mode [38]. The present study shows that the surface composition in low fractions might not affect the surface wettability, but the surface wetting transitions and contact angle hysteresis can be altered significantly by manipulating the droplet–surface interaction, which has never been reported before. We demonstrate the dynamic wetting behavior of a pressed water droplet on anodized alumina, which was modified with responsive polymer brushes after pretreatment with a dilute initiator [39]. The wetting transition between super hydrophobicity and hydrophilicity may be achieved depending on the responsiveness between droplets of different pH, the concentrations of electrolytes, the environmental temperature, and surface-grafted stimuli-responsive polymer brushes. The distinct CA changes give the surface double-faced wetting characteristics. The general aim of this research is developing a superhydrophobic surface by a sol–gel polymerization method involving suitable polymers of different types with various functionalities. Inorganic particles and metal oxides help these polymers to develop super-hydrophobicity and substantially increase the self-cleaning functionality of currently available surfaces. These developments include fast cleaning and faster super drying with the highest quality of the overall surface. Hopefully, these developments will lead to commercially available superhydrophobic surface materials. A dielectric materials measurement can provide critical design parameter information form any applications. For example, the loss of a cable insulator, the impedance of a substrate, or the frequency of a dielectric resonator. This information is also useful for improving packaging designs. More recent applications in the area of industrial microwave processing of food, rubber, plastic, and ceramics have also were found to benefit from knowledge of dielectric properties. Hydrophobicity of insulating materials is treated as the resistance to formation of conducting water tracks that increase leakage current, chances of flashover, and other deterioration effects. The superior performances of polymer outdoor insulating materials are regarded as the contribution of their hydrophobic surfaces. Super-hydrophobic surfaces were made by miniemulsion formation through sophisticated polymerization techniques and by comparison with natural hydrophobic surfaces. The super-hydrophobic polymers were doped by stabilized inorganic particles to boost the superhydrophobic performance of the surfaces using metal alkoxides (SiO2 and with silica/chlorotrimethylsilane, SiO2/ CTMS) as a requirement for super-hydrophobicity. Multilayer samples with a modified organic–inorganic top layer could produce water contact angles of up to 1308.