New coating ‘self-cleans’ and prevents fogging

The coating of a thin double layered silicon dioxide-titanium dioxide film is applied through a two-step technique: the plastic surface is first treated with oxygen plasma, then the thin double layered film is deposited on the plastic surface using pulse laser deposition.

The NTU researchers said that compared to similar industrial methods their approach offers better control of the film’s thickness and structure during fabrication and results in a higher quality film.

When subjected to abrasion using a cheese cloth pad, a standard test for optical coating, and an adhesion test using cellophane tapes, the coating maintained good durability.

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Fogging occurs when water vapour condenses as water droplets on a surface, and so the anti-fogging performance of coating is measured by the speed at which the condensed water droplets spread into a uniform film that does not block vision. In experiments on the new coating, digital fast frame imaging showed a water droplet spreading within 93 milliseconds.