Preparation of fluorinated PCL porous microspheres and a super-hydrophobic coating on fabrics via electrospraying.

In this study, fluorinated polycaprolactone (PCL) block polymers with different fluorine contents were synthesized via atom transfer radical polymerization (ATRP). An electrospraying technique was used to prepare fluorinated PCL microspheres with different microstructures. In contrast to the golf ball shape of unmodified PCL microspheres displaying porous pits on the surface, block polymer PCL-PTFOA(2 h) and PCL-PTFOA(6 h) microsphere surfaces displayed regular honeycomb-like pore structures. Thermally induced and evaporation-induced phase separations are proposed as the main mechanisms involved in the formation of the porous microstructures. The micro-phase separation between the two blocks of the fluorinated PCL copolymer is another factor that promoted the uniform collapse on the microsphere surface and the formation of its rugged wall. The surface roughness of the porous microspheres significantly improved their hydrophobicity, generating coating contact angles on aluminium foil substrates that measured as high as 162.4 ± 1.5°, which revealed that the surfaces were super-hydrophobic. Lastly, cotton fabric was directly coated with the fluorinated polymer microspheres via electrospraying, resulting in super-hydrophobic surfaces and CAs reaching 160.0 ± 1.3°. The results demonstrate that electrospraying is a simple, innovative and cost-effective method for preparing polymer microspheres with controllable microstructures for fabric coating applications.