Properties of Mosquito Repellent-Plasticized Poly(lactic acid) Strands.

António B Mapossa,Jorge López-Beceiro,Dennis S Moyo,Ramón Artiaga,Ana María Díaz-Díaz,Thabang N Mphateng,Walter W Focke,Walter W Focke

doi:10.3390/molecules26195890

António B Mapossa, Jorge López-Beceiro + Show 6 more

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https://doi.org/10.3390/molecules26195890

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Abstract

Poly(lactic acid) (PLA) is an attractive candidate for replacing petrochemical polymers because it is fully biodegradable. This study investigated the potential of PLA as a sustainable and environmentally friendly alternative material that can be developed into commercially viable wearable mosquito repellent devices with desirable characteristics. PLA strands containing DEET and IR3535 were prepared by twin screw extrusion compounding and simultaneously functioned as plasticizers for the polymer. The plasticizing effect was investigated by thermal and rheological studies. DSC studies showed that the addition of DEET and IR3535 into PLA strands reduced the glass transition temperature consistent with predictions of the Fox equation, thus proving their efficiency as plasticizers. The rheology of molten samples of neat PLA and PLA/repellents blends, evaluated at 200 °C, was consistent with shear-thinning pseudoplastic behaviour. Raman studies revealed a nonlinear concentration gradient for DEET in the PLA strand, indicating non-Fickian Type II transport controlling the desorption process. Release data obtained at 50 °C showed initial rapid release followed by a slower, near constant rate at longer times. The release rate data were fitted to a novel modification of the Peppas-Sahlin desorption model.

Highlights

The mass loss curves indicate delayed volatilisation when the repellents were trapped inside the Poly(lactic acid) (PLA) matrix
The melts showed pseudoplastic rheological behaviour at 200 ◦ C with the fluidity improving with repellent content
The desorption rates measured at 50 ◦ C showed fast initial release behaviour that slowed down to a near steady rate at longer times

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Malaria is a leading cause of illness and death in countries where the disease is endemic [1]. The disease is caused by the bite of mosquitoes carrying Plasmodium parasites [1]. Children younger than five years and pregnant women are most susceptible to malaria.

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