Wettability of Electrospun Films of Microphase-Separated Block Copolymers with 3,3,3-Trifluoropropyl Substituted Siloxane Segments

Fluorinated polymers or chemicals with long length of fluorinated tail are often used to enhance the hydrophobicity and oleophobicity of surfaces. In this work, superhydrophobic and highly solvent-repellent surfaces were fabricated by using a series of block copolymers with 3,3,3-trifluoropropyl substituted siloxane segments via an electrospinning process. The contact angles of deionized water on the electrospun films are higher than 150° and the water roll-off angles are less than 10°, denoting a superhydrophobic property for the electrospun films. The electrospun films can also exhibit contact angles higher than 150° for glycerol, formamide, and diethylene glycol. Moreover, it is surprising to find that very high contact angles with small roll-off angles on the electrospun films could be obtained by using the oil liquids colored by 0.4 wt % oil-soluble dyes. By investigating the properties of the thin/electrospun films of block copolymers, it is found that the microphase-separation behavior of block copolymers could be an important reason for the formation of nanoscale surface roughness. The electrospun films can exhibit superhydrophobicity and high solvent resistance, owing to the formation of multiscale surface roughness as well as the surface segregation of low surface energy groups.