Atmospheric pressure Townsend discharges as a promising tool for the one‐step deposition of antifogging coatings from N2O/TMCTS mixtures

• Published in: Plasma processes and polymers 2020-07, Vol.17 (7), p.n/a
• Main Authors: Rodríguez Durán, Iván, Durocher‐Jean, Antoine, Profili, Jacopo, Stafford, Luc, Laroche, Gaétan
• Format: Article
• Language: English
• Subjects: antifogging coatings; Atmospheric pressure; Coatings; Contact angle; Deposition; Dielectric barrier discharge; dielectric barrier discharges (DBD); Fogging; Glass; Nitrous oxide; surface composition; tetramethylcyclotetrasiloxane (TMCTS); wettability
• ISSN: 1612-8850; 1612-8869
• DOI: 10.1002/ppap.201900186

The need to ensuring the “see‐through” property of transparent materials when exposed to sudden temperature changes or very humid conditions has encouraged the development of antifogging strategies, such as the deposition of (super)hydrophilic coatings. However, despite the effectiveness of these coatings in combating the effects of fogging, most of the coating techniques explored to date are typically time‐consuming and environment‐unfriendly. Bearing this in mind, we demonstrate that the application of dielectric barrier discharges operated at atmospheric pressure proves to be successful in preparing antifogging coatings on glass samples from 1,3,5,7‐tetramethylcyclotetrasiloxane (TMCTS) and nitrous oxide (N2O). The antifogging performance of the coatings was found to be governed by the [N2O]/[TMCTS] ratio and not by the [N2O] + [TMCTS] sum. Coatings prepared under a [N2O]/[TMCTS] = 30 were superhydrophilic (water contact angles ≈ 5°–10°) due to surface silanol groups and endowed glass samples with a superior antifogging property, as revealed by the ASTM F 659‐06 test. In contrast, because of the lesser hydrophilicity (water contact angles ≈ 60°), coatings prepared under a [N2O]/[TMCTS] = 10 did not endow glass samples with antifogging property. Regardless of the deposition conditions, the plasma‐deposited coatings displayed crack‐free smooth surfaces (Rrms = 2−4 nm). The anti‐fogging performance of [N2O]/[TMCTS] coatings deposited in an atmospheric dielectric barrier discharge was found to be governed by the ratio of [N2O] to [TMCTS]. Coatings prepared under a [N2O]/[TMCTS] = 30 were superhydrophilic due to surface silanol groups and conferred superior anti‐fogging performance to glass samples. In contrast, coatings prepared under a [N2O]/[TMCTS] = 10 did not endow glass samples with anti‐fogging performance.