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Study of Self-Cleaning Silica Nano Coatings

Hadinejad Sheikh, Farshad | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56128 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Afshar, Abdollah
  7. Abstract:
  8. It has always been a challenge to make self-cleaning coatings based on super-hydrophobic properties that can provide the necessary features to be operational in the industry. One of these necessary features is the ability to easily apply the coating on the substrate and reduce the cost by finding the optimal amount of consumables. Therefore, in this research, at first, it was tried to produce silica nanoparticles with a particle size of less than 011 nm using the Stober method, and then the surface of the synthesized nanoparticles was coated with HDTMS (Hexadecyltrimethoxysilane) to make the silica particles, which are hydrophilic in nature, hydrophobic. According to the conducted studies, the effect of the concentration of functionalized nanoparticles along with the concentration of functionalizing agent on the surface of nanoparticles has been investigated. Glass is chosen as the substrate. After performing the steps of surface preparation for glass samples and preparation of colloidal solution, this solution is applied on the glass surface by spraying method. Then, the surface roughness, morphology, coating thickness, optical properties of the samples, along with the particle size without the use of surface modifiers of nanoparticles and the size of the functionalized particles, as well as the chemical composition, have been investigated. Equipment and tests such as DLS, FESEM, EDS, AFM, FTIR, UV-Vis and contact angle test have been used to investigate these cases. From the data of DLS test, it is clear that the most important variable to obtain nanoparticles under 011 nm is pH control at 01. The images obtained from FESEM and AFM show the roughness required to reach superhydrophobicity, and the average roughness is around 52 nm. The diagrams obtained from UV-Vis also confirm the extremely transparent coatings. Also, from the analysis of FESEM, AFM and UV-Vis data, it can be concluded that the coating thickness varies from 21 to 021 nm. The results of FTIR and EDS also show that -OH bonds with silica particles have disappeared and instead of them –CH0, -CH5 and C-O bonds are observed, which indicates the functionalization of the nanoparticles surface, and it is also clear from the elemental mapping that the distribution of these elements is uniform to a large extent. By examining the results of the contact angle, the optimal amount of HDTMS for functionalizing the surface of nanoparticles is 0.2 mL, with a contact angle of 0251, and also, the optimal amount of functionalized silica nanoparticles is 2mg/mL with a contact angle of 0301
  9. Keywords:
  10. Self-Cleaning ; Silica Nanoparticles ; Glass ; Superhydrophobic Coating ; Hexadecyltrimethoxysilane (HDTMS) ; Spray

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