Preparation of breathable and superhydrophobic polyurethane electrospun webs with silica nanoparticles

Polyurethane (PU) is a unique polymeric material with excellent chemical and physical properties and is widely used in textile materials. There has been a need for superhydrophobic PU for wider applications, such as coating materials. In this research, SiO₂ nanoparticle (SNP) incorporated PU webs with superhydrophobic and breathable properties were prepared by one-step sol-gel electrospinning and post-treated with a non-fluorinated water repellent chemical, n-dodecyltrimethoxysilane (DTMS). SNPs were observed to be distributed evenly all over the fiber surfaces when 1–6 wt% SNP and tetraethoxysilane (TEOS)/acetic acid solution were added. TEOS was hydrolyzed to form larger nanoparticles while developing cross-linking with aromatic groups of the PU matrix. Interestingly, the addition of 20 nm SNPs was thought to act as nucleating seeds for enhanced hydrolysis of TEOS within the PU matrix. The hierarchical surface roughness consists of different sized SNPs and polymer beads, which resulted in superhydrophobicity with water contact angles as high as 157° and shedding angles as low as 5°. Laminating PU/SNP/DTMS webs onto polyester fabrics maintained the air permeability and water vapor transmission rate, which proves the potential of the developed PU/SNP/DTMS webs for practical applications as textile laminate materials with simple processing.