Relation between the size of fog droplets and their contact angles with CR39 surfaces

Abstract

The formation of fog on CR39 surfaces has been studied. Water droplets form fog coalesce with time, especially during the first 20 s at the beginning of the formation of fog. Consequently, their mean diameter increases. Formation of fog being related to the wettability of the surfaces, the latter has been increased by the implantation of Ar ions into CR39 surfaces under an oxygen partial pressure. A very wetting CR39 surface with advancing (ACA) and receding (RCA) contact angles below 5° has been obtained with an implantation dose of 1.28 × 1017 Ar+ cm−2. In this condition, no formation of fog was observed. Characterization using x-ray photoelectron spectroscopy has shown that the molecular structure of CR39 is strongly modified by Ar+ implantation, which would be responsible for the increase in wettability. Unfortunately, both ACA and RCA increase with time, which is called ageing, and the formation of fog is again observed. The diameter and concentration of water droplets forming fog have been plotted against the contact angle. These plots show that no formation of fog occurs for ACA < ∼40°. Usually, the ACA reaches 40° after an ageing time of ∼200 h. A He pre-implantation with a dose of 5 × 1015 He+ cm−2 and an energy of 2 keV, sufficient to push the ions deeper than the Ar depth profile, delays the ageing effect in such a way that ACA ≅ 40° is reached after ∼2000 h and no formation of fog is observed during these first ∼2000 h.

Dynamic polygonal spreading of a droplet on a lyophilic pillar-arrayed surface

“…For rough surface in our case, θ could be simplify to ∼ 1 − s hR [19]. Considering R b ∼ R f (ε is independent of time), which is validated by previous work [26], the velocity could be expressed by Plug the instant wetted area S ∼ R 2 f into Equation (6), and then the dimensionless solution S S 0 ∼ 2∕ 3 is obtained, where S 0 is the initial projected area, S S 0 is the dimensionless wetted area, and = t LV R 0 is the dimensionless time, respectively.…”

“…Spreading of a droplet on a micro-structured surface is prevalent in nature, [1,2] and is of key importance in a wide range of applications, such as DNA technologies, [3,4] fog-harvesting, [5,6] inkjet printing, [7][8][9] biomedicine [10,11] and microfluidics. [12,13] To develop these practical applications, dynamic wetting behaviours of a droplet on a textured surface have been investigated extensively in recent years.…”

Ultrafast Oleophobic–Hydrophilic Switching Surfaces for Antifogging, Self-Cleaning, and Oil–Water Separation

“…52 Copolymer-fluorosurfactant complex dip coated glass slides using dimethylformamide solvent were found to retain their transparency (anti-fogging) during liquid water spray exposure, Figure 4. Self-cleaning properties for the copolymer-fluorosurfactant dip coated glass slides were demonstrated by rinsing off fouling oils with just water, Figure 5.…”

Self‐Cleaning and Anti‐Fog Surfaces via Stimuli‐Responsive Polymer Brushes

“…An advancing water contact angle of < 40°has been experimentally established as a critical threshold to prevent fogging on surfaces. [43] Surfaces with advancing water contact angles greater than 40°will result in moisture condensing in discrete droplets on the surface, which scatter light creating a translucent fog.…”