Polyvinylidene difluoride (PVDF) microsphere aggregate films with exceptionally high specific surface area have been synthesized using the Nonsolvent-Induced Phase Separation (NIPS) method. These structures are similar to the highly hydrophobic leaves of the plant Colocasia esculenta (Taro) in both geometry and physical properties. The individual spheres mimic the rough micro-nodules of the leaf, while clustering of the microspheres provides an additional layer of hierarchy, emulating the water-shedding capabilities of Colocasia esculenta. The microsphere aggregates have been created by spinodal decomposition of a ternary solution of PVDF, dimethylformamide (DMF), and water, initiated by submerging spin-cast films in a water bath. The sphere diameter has been varied from 250 nm to 4 µm by modulating the initial composition of the system, while the film thickness is determined by the spinning speed. Additionally, the sphere surface roughness has been controlled by changing the phase separation temperature, and consequently, the relative diffusion rates of DMF and water. These microsphere clusters are among the most superhydrophobic pure polymer structures produced to date, with contact angles in excess of 171°, contact angle hysteresis less than 12°, and a slide angle of 3°. Furthermore, the synthesis technique is reproducible and easily scalable, and the coating can be sprayed on to any surface to impart anti-microbial, self-cleaning, chemical-resistant, and water-repellent properties.

Nonsolvent-induced phase separation synthesis of biomimetic PVDF microspheres for superhydrophobic coatings

251st National Meeting (2016)

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