Superhydrophobic micro-nano structures on silicone rubber by nanosecond laser processing

Abstract

This paper demonstrates laser surface modification of silicone rubber using an economic and efficient nanosecond fibre laser. The resulting surface morphology shows that micro-nano structures leading to an increase in the surface slope were formed after processing. The effect of laser power on the surface wettability was investigated demonstrating that the contact angle of the silicone rubber surface increased with increasing laser fluence. The water contact angle on the treated surface reached ∼160° with a rolling-off angle of ∼3° when the laser fluence reached 10 J cm-2. After laser processing, both the roughness and root mean square slope of the silicone rubber surface increased with increasing fluence and reached maximum at a fluence of 10 J cm-2. An analysis of the pre- and post processing surfaces suggested there were no significant compositional changes, but there were some micro-structural changes to the polymer chain, namely, cleavage of the Si-O-Si bonds. It is thus proposed that the hierarchical micro-nano structures and hence the change in the root mean square slope of the silicone rubber surface induced by laser irradiation are the primary reasons for its superhydrophobicity. The preparation of superhydrophobic silicone rubber can have important applications in self-cleaning, anti-icing, and anti-pollution.