Competition between Liquid-liquid De-mixing, Crystallization, and Glass Transition in Solutions of PLA of Different Stereochemistry and DEET

Sungkapreecha, Chanita; Kaci, Mustapha; Androsch, René

doi:10.1007/s10118-019-2314-0

Cited by 11 publications

(8 citation statements)

References 20 publications

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“…For both polymers, TIPS has been proven as a successful route to form scaffolds for many applications, in particular in the biomedical sector. − For both, PLLA and PBS, basic information about the phase behavior with DEET in the case of solvent-rich compositions were collected, confirming the formation of solutions at elevated temperature as a precondition for S–L TIPS. During cooling to ambient temperature, crystallization of the polymer occurs, with the liquid repellent-rich phase then accommodated in intercrystalline, micrometer-sized pores. − …”

Section: Introductionmentioning

confidence: 99%

Crystallization-Induced Polymer Scaffold Formation in the Polymer/Drug Delivery System Poly(l-lactic acid)/Ethyl Butylacetylaminopropionate (PLLA/IR3535)

Yener

Hillrichs

et al. 2021

Biomacromolecules

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Polymer/mosquito-repellent scaffolds exhibit increasing importance in long-lasting human skin protection to be used as wearable devices and allowing for controlled release of repellents. In this study, ethyl butylacetylaminopropionate (IR3535) was used as a human and environmental friendly active mosquito-repellent serving as a solvent to form functional poly(l-lactic acid) (PLLA) scaffolds by crystallization-based solid–liquid thermally induced phase separation. Crystallization of PLLA in the presence of IR3535 is faster than melt-crystallization of neat PLLA, and in the investigated concentration range from 5 to 50 mass % PLLA, its maximum crystallization rate increases with the PLLA content, by both, increases of the maximum crystal growth rate and of the nuclei density. By adjusting the polymer concentration and the crystallization temperature, microporous scaffolds of different fine structures are obtained, hosting the mosquito-repellent in intra- and interspherulitic pores for its intended later evaporation.

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Section: Introductionmentioning

confidence: 99%

Crystallization-Induced Polymer Scaffold Formation in the Polymer/Drug Delivery System Poly(l-lactic acid)/Ethyl Butylacetylaminopropionate (PLLA/IR3535)

Yener

Hillrichs

et al. 2021

Biomacromolecules

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“…Several polymer/repellent systems have been explored, including low-density polyethylene (LLDPE)/citronellal, poly( l -lactic acid) (PLLA)/ N , N -diethyl-3-methylbenzamide (DEET), − or PLLA/ethyl butylacetylaminopropionate (IR3535), with all of these studies focusing on repellent-rich mixtures and on gaining fundamental information about systems thermodynamics.…”

Section: Introductionmentioning

confidence: 99%

Slow-DEET-Release Mosquito-Repellent System Based on Poly(butylene succinate)

et al. 2022

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Bio-sourced and biodegradable poly(butylene succinate) (PBS) strands containing up to 40 m% mosquito-repellent N,N-diethyl-3-methylbenzamide (DEET) were obtained by extrusion, for an initial evaluation of the DEET evaporation characteristics and the possible application of such strands as biodegradable slow-release repellent-delivery devices. For DEET concentrations up to 20 m%, DEET is entrapped in the semicrystalline spherulitic superstructure of PBS. In contrast, at higher DEET concentrations, the liquid repellent, at least partially, is not fully incorporated in the PBS spherulites rather than segregates to form an own macrophase. Quantification of the release of DEET to the environment by thermogravimetric analysis at different temperatures between 60 and 100 °C allowed estimation of the evaporation rate at lower service temperatures, suggesting an extremely low release rate with a time constant of the order of magnitude of 1−2 years at 25 °C, independent of the initial concentration.

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“…Nevertheless, the mismanagement of waste in Africa is already impacting human and environmental health [ 5 ]. Therefore, the present study and other associated investigations [ 6 , 7 , 8 , 9 , 10 , 11 ] opted to investigate poly(lactic acid) as an alternative polymer matrix for repellent incorporation.…”

Section: Introductionmentioning

confidence: 99%

“…The incorporation of mosquito repellents into PLA was studied previously [ 6 , 7 , 8 , 9 , 10 , 11 ]. Di Lorenzo and Longo [ 19 ] prepared PLLA/DEET blends, containing up to 4.5 wt.% of the repellent, via melt extrusion.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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Competition between Liquid-liquid De-mixing, Crystallization, and Glass Transition in Solutions of PLA of Different Stereochemistry and DEET

Cited by 11 publications

References 20 publications

Crystallization-Induced Polymer Scaffold Formation in the Polymer/Drug Delivery System Poly(l-lactic acid)/Ethyl Butylacetylaminopropionate (PLLA/IR3535)

Crystallization-Induced Polymer Scaffold Formation in the Polymer/Drug Delivery System Poly(l-lactic acid)/Ethyl Butylacetylaminopropionate (PLLA/IR3535)

Slow-DEET-Release Mosquito-Repellent System Based on Poly(butylene succinate)

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

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