Rapid mold-free fabrication of long functional PDMS fibers

Abstract

Polydimethylsiloxane (PDMS), an optically transparent and inert material, is widely used in biological and semiconductor applications owing to its excellent chemical stability and moldability. This study proposes a thermally induced wet spinning method for the fabrication of long PDMS fibers with a constant width. PDMS is a thermoset polymer that undergoes chemical crosslinking when heated, and the thermally induced wet spinning process allows for the formation of fibers without a mold. A rapid thermal curing step was used to instantly solidify the thermoset polymer, where immediate chemical crosslinking of fluid PDMS solution was achieved upon contact with an oil coagulation bath at 180–230 °C. A rapid stretching process was applied to pull out and control the width of the fiber, and the PDMS was stretched at a rate of 1.2–12.5 m/min during the crosslinking process. The fabricated pristine PDMS fibers were transparent and maintained a crosslinked network with excellent mechanical strength. In addition, the PDMS fibers were functionalized with silica nanoparticles, carbon nanotubes, and pores to adjust their transparency/opacity, conductivity, and heat insulation properties, respectively, for various applications. The proposed thermally induced wet spinning method shows promise for overcoming the limitations of existing molding methods, in which the PDMS fibers cannot be lengthened. Furthermore, the process is environmentally friendly and economical owing to the use of edible canola oil, which reduces the volume of harmful solvents and additives during fiber production.