Highly stretchable superhydrophobic surface by silica nanoparticle embedded electrospun fibrous mat.

Hypothesis: Obtaining simultaneous stretchability and superhydrophobicity remains a great challenge in stretchable electronics, and wearable devices. Inspired by natural surfaces, such as lotus leaf, surface roughness and coating materials are the fundamental requirements to achieve superhydrophobicity.

Experiments: We prepared an elastic fibrous mat by electrospinning of a composite solution made of thermoplastic elastomer as an organic polymer matrix, and silica nanoparticles as inorganic additives to support surface roughness. To enhance hydrophobicity, the pristine mat was immersed into a solution of fluorinated material, which can decrease the surface energy.

Findings: The pristine fibrous mat showed high stretchability (with more than 1000% strain), and superhydrophobicity (with a contact angle of 156°, and a sliding angle of 7.8°). Superhydrophobicity did not disappear when the fibrous mat was stretched up to 1000%. Sliding angles were less than 10° under different strain levels only in longitudinal direction, suggesting the stretchable superhydrophobic surface is effective in rolling off the water droplet in one direction. The fibrous mat was repeatedly stretched 1000 times to 1000% strain; the material showed stable stretchability and superhydrophobicity. Based on these observations, the resulting fibrous mat appears to be in the Cassie-Baxter wetting state.