Low-Temperature Preparation of Mechanically Robust and Contamination-Resistant Antireflective Coatings for Flexible Polymeric Glasses via Embedding of Silica Nanoparticles and HMDS Modification

Abstract

Mechanical and contamination-resistant properties are the most crucial and challenging issues that impede the practical applications of sol–gel antireflective (AR) coating. In this paper, we report a low-temperature vapor surface treatment strategy for the partial embedding and surface functionalization of silica nanoparticles (SNPs) on flexible polymeric glass substrates. SNPs, which were synthesized via the Stöber method, were partially embedded into the polymeric glass substrates by vapor-phase surface treatment using volatile chloroform. Further vapor-phase surface treatments by water and hexamethyldisilazane (HMDS) were applied successively to achieve high trimethylsilyl coverage of the SNPs. The HMDS modification could convert the polar surface of SNPs to a nonpolar surface for contamination resistance, while ammonia, as a byproduct generated, could help to cross-link the SNPs via self-condensation of silanol groups, thus hardening the coating. The SNP-CWH coated polymethylmethacrylate (PMMA) substrate shows an average transmittance of 98.62% in the wavelength region of 400–800 nm, which is 6.32% higher than that of the uncoated bare PMMA. The AR performance of SNP-CWH coated PMMA shows almost no degradation after 100 times of rubbing or bending, indicating the greatly enhanced abrasion resistance and flexibility. Furthermore, the SNP-CWH coating exhibits superior contamination-resistant property, where the transmittance curve of the coated substrate displays a barely noticeable change after exposure to a “dirty” environment with water and organic contaminants for 6 months. This work paves a new way for developing mechanically robust and contamination-resistant AR coating for polymeric substrates.

Preparation and Characterization of Some Sol-Gel Modified Silica Coatings Deposited on Polyvinyl Chloride (PVC) Substrates

“…The results indicated that the nanocomposite coating showed a reduction in the reflectance (6.29%). Wang et al [33] reported the surface functionalization of silica nanoparticles on polycarbonate (PC) and polymethylmethacrylate (PMMA) glass substrates. The obtained results showed that the coated PC/PMMA substrates exhibit high optical transmission (98%), superior abrasion resistance after 100 cycles and contamination resistance performed at room temperature.…”

Study on the Hydrophobic Modification of MTES/NH3 Vapor Surface Treatment for SiO2 Broadband Anti-Reflection Coating

“…A hydrophobic AR film on polymer substrates is obtained by the sol–gel method with an ammonia vapor treatment, and it shows the mechanism of Ostwald-ripening-type structural modification under vapor treatment [ 12 ]. Then, ammonia is used with organic silane to modify film in the later study, an AR coating with good stability in different environment is obtained by the combined vapor phase surface treatment [ 13 , 14 ]. The vapor treatment process is simple to implement and can be carried out at room temperature and atmospheric pressure with minimal equipment requirements and minimal substrate handling [ 15 ].…”

SiO2 Nanoparticles Modified by Bridged Polysilsesquioxane-Based Protective Coatings for Moisture Proofing and Antireflection Applications

“…The multiple hydrophobic functionalized SiO 2 NPs have been prepared through the efficient reaction between the amino group containing SiO 2 NPs and the isocyanate containing hydrophobic surface modifiers synthesized by normal alcohols. The moisture-proof property of this coating depends on hydrophobic groups exposed on the coating surface, − and the antireflective property of the coating relies on their porous structure formed by random or ordered stacking of hydrophobic nanoparticles. However, hydrophobic modifying of nanoparticles or coatings has an adverse influence on the adhesive force between coatings and the substrates, which results in the coating with poor mechanical properties .…”