Sustainable Electrospun Poly(l‑lactic acid) Fibers for Controlled Release of the Mosquito-Repellent Ethyl Butylacetylaminopropionate (IR3535)

Fibers composed of poly(l-lactic acid) (PLLA) and the mosquito-repellent ethyl butylacetylaminopropionate (IR3535) were prepared by solution electrospinning. Defect-free and uniform monoaxial fibers with a diameter of the order of magnitude of 1 μm were obtained. Thermogravimetric analyses showed that it is possible to incorporate more than 40 m% of IR3535 into the PLLA fibers. Thermal and structural characterization indicated that IR3535 facilitates the crystallization of PLLA and formation of orthorhombic α-crystals during electrospinning. IR3535 has a plasticizing effect on PLLA, as detected by the decrease in the glass transition temperature. The release of IR3535 from PLLA/IR3535 fibers to the environment was quantified by thermogravimetric analysis at different temperatures ranging from 60 to 100 °C, suggesting rather slow evaporation of the repellent, with a time constant of few days at body temperature. The observed results indicate a possible use of electrospun PLLA/IR3535 fiber mats as part of a long-lasting repellent-delivery system and application in the field of combating diseases caused by mosquito bites