Solvent-free thermocuring electrospinning to fabricate ultrathin polyurethane fibers with high conductivity by in situ polymerization of polyaniline

Abstract

A new solvent-free thermal assisted electrospinning (e-spinning) process for the preparation of polyurethane (PU) microfibers has been developed. Based on the synthetic process of conventional PU, the synthesis of the PU precursor solution in this work was improved for the solventless e-spinning process. Low molecular weight (low-M_w) polyol (PTMG-500) was employed for preparing the prepolymer, and another low-M_w polyol (PEG-400) was used as the chain extender. During the chain extension, e-spinning was conducted and assisted by thermal radiation (∼50 °C), and PU microfibers with an average diameter of 25–60 μm were fabricated. The spinnable viscosity range in this e-spinning process was 1000–2500 dPa s. In addition, 2,2-bis(hydroxymethyl)propionic acid (DMPA) was introduced into the precursor solution to partially take the place of the chain extender (PEG-400), and thus the hydrophilicity of the as-spun fibrous mat was improved, which was helpful for in situ polymerization of polyaniline (PANi) on the fibers' surface to obtain conductive PU/PANi composite fibers. This thermal assisted e-spinning process is a solvent-free and eco-friendly process, which may become an interesting approach to fabricate a variety of PU-based functional fibers with applications in protective and anti-corrosive coatings, antistatic fabrics, and sensors.