Facile preparation of super-hydrophobic fabrics composed of fibres with microporous or microspherical coatings using the static breath figure method

Abstract

Fluorinated PTFOA-b-PS(2 h) and PTFOA-b-PS(4 h) block copolymers with controllable molecular weights were synthesised by atom transfer radical polymerisation (ATRP) and used to form microporous and microspherical coatings on fibres using the static breath figure (BF) method. The structures and properties of the coatings were examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and water contact angle (WCA) analysis. The fibre surface was complete coated with a microporous polymer in a water atmosphere using a 20 mg/mL PTFOA-b-PS(4 h) solution in CS2 as the finishing agent. The as-prepared fabric showed excellent hydrophobicity, with a WCA of 147.2 ± 1.6°. On the other hand, the fibre surfaces were coated with excellent polymer microspheres in a methanolic atmosphere using a 10 mg/mL PTFOA-b-PS(2 h) solution in THF; the WCA of the microsphere-coated fabric was 151.1 ± 0.1°. The WCA and EDS results reveal that synergism between the high roughness and low surface energy of the microspherical coating endows the fabric with super-hydrophobicity. At the same time, silanised block copolymers were synthesised by the silanisation of PTFOA-b-PS(2 h) and PTFOA-b-PS(4 h) and used to prepare microporous and microspherical coatings on fabrics. SEM showed that the silanised-PTFOA-b-PS(4 h)-coated fabric has a uniform and completely microporous morphology. A comparative study showed that both PTFOA-b-PS(2 h) and silanised-PTFOA-b-PS(2 h) form microspheres on fibre surfaces and that the latter exhibited hierarchical micro-nanostructures; the surface of fabric coated with this silanised polymer is super-hydrophobic, with a WCA of 152.2 ± 2.3°. Elemental distributions were determined by EDS, which revealed that the silanised-PTFOA-b-PS(2 h) microspheres contain more surface-migrating fluoropolymer segments, which produce hierarchical micro-nanostructures due to micro-phase separation. The air permeabilities and hardnesses of the silanised polymer-coated fabrics were also studied.