Controlled synthesis of amphiphilic graft copolymer for superhydrophobic electrospun fibres with effective surface fluorine enrichment: the role of electric field and solvent

Effective surface fluorine enrichment has great potential application value for superhydrophobic electrospun films, which has presented a challenge to researchers. The aim is expected to be achieved by electrospinning functional polymers with controlled structure based on the polarization characteristics of functional groups in polymer chains and their directional ordering induced by an electric field. Herein, an amphiphilic graft copolymer of poly(methyl methacrylate-ran-hydroxypropyl acrylate)-graft-poly(dodecafluoroheptyl methacrylate) (PMMA-r-PHPA-g-PDFMA) was synthesized by the combination of free radical polymerization and atom transfer radical polymerization (ATRP). Superhydrophobic fibrous films with high surface fluorine atomic content of 29.1% and even up to 34.8% were fabricated by eletrospinning the resultant fluoropolymer. It is concluded that the electric field can drive the surface segregation of positively charged fluorinated groups and bulk segregation of negatively charged -OH groups, thus contributing to the effective surface fluorine enrichment, which was confirmed by XPS results. Additionally, we also found that the superhydrophobicity of electrospun films has no apparent dependence on fibre morphologies. The variation in the surface wettability can be attributed to the difference in surface compositions obtained by changing the applied electric field strength and solvents. This research would present potential application prospects in fabricating high surface fluorinated superhydrophobic electrospun fibres or novel surface functionalized electrospun fibres.