Electrospun Multifunctional Composite Fibers for Improved Warfighter Insect Protection

Conventional insect repellent treatments for fibers, fabrics, and garments suffer from limited durability to repeated laundering and, depending on the insecticide, potential irritation or toxicity. In this work, monofilament and coaxial electrospinning were employed to control the composition of hierarchically-structured functional micro- to nano-scale fibers for tunable insect repellent release. Specifically, picaridin was incorporated into Nylon-6,6 nanofibers for the first time via monofilament and coaxial electrospinning, in which the sheath component has potential to protect additives in the core for more durable fabrics and act as a diffusion barrier for extended release applications. The size and morphology of nylon fibers were unaffected by picaridin incorporation, even at loading concentrations up to 50 wt%. picaridin release kinetics were largely dependent on loading concentration and temperature, as picaridin-nylon intermolecular interactions were minimal affording diffusion based release. Importantly, coaxial fibers composed of nylon-picaridin core surrounded by a nylon sheath demonstrated altered release kinetics demonstrating the capability to further tune behavior.