Effect of DEET on the crystallinity of bicomponent poly(lactic acid) monofilaments

Reduction of malaria will require outdoor protection against infective mosquito bites. This might he provided by wearable mosquito repelling textiles, e.g., anklets that protect the lower limb regions. Towards this goal, melt-biodegradable, DEET-containing bicomponent PLA monofilaments, with a sheath-core structure, were spun on a laboratory rig. It is expected that the sheath degree of crystallinity and crystalline morphology affect the release rate of the DEET. Consequently, the effect of DEET was investigated by means of DSC. It was found that DEET greatly increases the mobility of the PLA chains, resulting in a lowered Tg, a lowered cold crystallization temperature and an increased degree of crystallinity. Furthermore, the presence of DEET favored the formation of the α´-crystal structure.