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

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.

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

“…Incorporating the repellent IR3535 into bio-sourced and biodegradable PLLA opens the way to the realization of an environment-friendly repellent-delivery device. After successful testing of melt extrusion , and 3D printing of semi-finished and final products of the PLLA/IR3535 system, in this work, electrospinning of fiber mats as an alternative technology for obtaining such an environment-friendly repellent-delivery system is investigated. By systematic variation of the electrospinning parameters, including voltage, nozzle-to-collector distance, flow rate, and solution composition, uniform fibers with a diameter close to 1 μm and containing a large amount of the repellent, exceeding 40 m%, were obtained.…”

“…By systematic variation of the electrospinning parameters, including voltage, nozzle-to-collector distance, flow rate, and solution composition, uniform fibers with a diameter close to 1 μm and containing a large amount of the repellent, exceeding 40 m%, were obtained. Such a high amount of repellent was impossible to incorporate into the polymeric carrier by melt extrusion and 3D printing, ,, where only up to about 25 m% IR3535 was added. Thermal and structural analyses revealed that IR3535 results in a decrease in the glass transition temperature of the polymer component, confirming thermodynamic solubility, as suggested in earlier works, , and causing plasticization of the amorphous PLLA phase.…”

“…As such, in-depth analysis of the glass transition temperature by employing fast scanning chip calorimetry combined with in situ evaporation of the liquid to achieve controlled change of the system composition has revealed that PDLLA and IR3535 are thermodynamically miscible in the entire composition range . Regarding the polymer-rich part of the PLLA/IR3535 system, IR3535 acts as a functional plasticizer of PLLA, , offering additional advantages from the point of view of reducing the inherent brittleness of PLLA. , Recently, PLLA-parts/products accommodating up to 25 m% of IR3535 were manufactured by classical melt extrusion , and 3D printing, emphasizing their potential for controlled long-term release of IR3535. Since in the case of electrospun fibers, the carrier geometry/shape is qualitatively different compared to scaffold-like bulk structures and products with a rather low surface-to-volume ratio, it is expected that the IR3535-release characteristics are different, and that personal-protection devices based on fibers can be generated.…”

“…As such, in-depth analysis of the glass transition temperature by employing fast scanning chip calorimetry combined with in situ evaporation of the liquid to achieve controlled change of the system composition has revealed that PDLLA and IR3535 are thermodynamically miscible in the entire composition range. 20 Regarding the polymer-rich part of the PLLA/IR3535 system, IR3535 acts as a functional plasticizer of PLLA, 21,22 offering additional advantages from the point of view of reducing the inherent brittleness of PLLA. 23,24 Recently, PLLA-parts/products accommodating up to 25 m% of IR3535 were manufactured by classical melt extrusion 21,22 and 3D printing, 25 emphasizing their potential for controlled long-term release of IR3535.…”

Structure, Properties, and Release Kinetics of the Polymer/Insect Repellent System Poly (l-Lactic Acid)/Ethyl Butylacetylaminopropionate (PLLA/IR3535)

“…Recent studies have proven that PLLA can be used as a carrier/drug delivery reservoir for the repellent IR3535 [39][40][41]. Early investigations focused on the evaluation of the repellent/solvent-rich part of the PLLA/IR3535 system for the preparation of scaffolds for the controlled release of IR3535 into the environment [40].…”