Tuning hydrophobicity of a fluorinated terpolymer in differently assembled thin films

What is it about?

In the current report, casting from good solvent (acetone) and casting from mixed solvent and nonsolvent were employed for preparing thin films of terpolymer of Tetrafluoroethylene (TFE), Hexafluoropropylene (HFP), and Vinylidene fluoride (VDF) (THV), on silicon wafers. These films revealed various morphologies and wetting behaviors depending on the solution concentration, temperature, and thin film preparation method. The THV thin films prepared by casting from good solvent showed smooth morphology with holes. The thin film prepared from a 3 wt % THV/acetone solution by casting from good solvent at 15 8C demonstrated spheres in addition to the smooth morphology, while the thin film prepared from a 5 wt % THV/acetone solution at 15 8C by casting from good solventhad a mesh-like structure with some linked spheres. Casting the thin films from mixed solvent and nonsolvent resulted in various morphologies such as different sphere sizes embedded in a dense film layer, and hexagonal close packed structures. The thin films prepared by casting from good solvent showed a slightly hydrophobic character, with a measured water contact angle of approximately 99 degrees, while the nonsolvent cast films had a water contact angle as high as 145 degrees.

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Why is it important?

It shows both tuning morphology and wetting behavior of a fluorinated terpolymer. In addition, the correlations between lower surface energy groups such as -CF2 and -CF3 and hydrophobicity, and roughness and hydrophobicity are revealed.