Development of polyolefin bicomponent filaments as controlled release devices of volatile repellents for use in malaria vector control

Abstract

The work presented here describes the development of controlled release and affordable mosquito repellent bicomponent polymer filaments. These filaments may be used in the production of alternative malaria vector control interventions aimed at reducing outdoor malaria transmission in resource-limited communities. The approach was to develop a bicomponent polymer filament with a core containing the volatile repellent active and an outer membrane layer that reduces the rate at which a volatile active is released to the atmosphere. The bicomponent filament was produced by a simple melt extrusion and drawing process. The core polymer used was poly(ethylene-co-vinyl acetate) (EVA) and the sheath polymer was high density polyethylene (HDPE). 40 wt.% N,N-Diethyl-m-toluamide (DEET) was incorporated into the EVA via a simple absorption process at a temperature of approximately 81 °C. Scanning electron microscopy (SEM) studies indicated that a bicomponent core-sheath structure was successfully formed by the melt extrusion and drawing process. Raman studies showed that a concentration gradient developed across the bicomponent filament after the manufacturing process. The Raman results suggest that the release of the repellent from the bicomponent filament is a diffusion controlled process, a characteristic of controlled release. With these findings, the study should proceed to the upscale of repellent impregnated bicomponent yarn production and fabric knitting. Such a fabric can be further studied for effectivenes in reducing outdoor malaria transmission in laboratory and field trials.