ABSTRACT
Pheromone eluting oligolactide (OLA) microcapsules immobilized in electrospun biodegradable polyester nanofibers were obtained by electrospinning of aqueous dispersions of the microcapsules. OLA was prepared by conventional melt polycondensation of lactic acid. Following the protocol of the solvent displacement method, OLA was dissolved in acetone and mixed with Brij S20 and the pheromone of the European grape vine moth, Lobesia Botrana, (E,Z)-7,9-dodecadien-l-yl acetate (DA). Up to 32 wt % of this mixture could be dispersed in water with colloidal stability of several weeks without any sedimentation. Without DA as well as OLA, no stable dispersions of OLA in water were obtained. Replacement of DA by classical hydrophobes typically used for miniemulsions did not yield stable dispersions, but the addition of octyl acetate, which shows structural similarity to DA, yielded stable dispersions in water up to 10 wt %. Dispersions of OLA/DA were successfully electrospun in combination with an aqueous dispersion of a biodegradable block copolyester resulting in water-stable nanofibers containing OLA/DA microcapsules. Release of DA from microcapsules and fibers was retarded in comparison with non-encapsulated DA, as shown by model studies.
Subject(s)
Dodecanol/analogs & derivatives , Insect Repellents/chemical synthesis , Moths/chemistry , Pheromones/chemistry , Polyesters/chemistry , Acetates/chemistry , Animals , Biodegradation, Environmental , Capsules/chemistry , Dodecanol/chemistry , Electrochemistry , Emulsions , Hydrophobic and Hydrophilic Interactions , Microscopy, Electron, Scanning , Nanofibers , Particle Size , Solubility , Solvents , Vitis , WaterABSTRACT
Poly(hexamethylene adipate)-PEO block copolymers (PHA-b-PEO) with different PEO contents were synthesized and processed to aqueous suspensions with high solid contents by a solvent displacement method followed by dialysis. The best suspension displayed a solid content of 16 wt.-% and an average particle size of 108 nm. This suspension was mixed with a small amount of high molecular weight PEO and Brij78 and electrospun into corresponding nanofibers. After extraction with water, nanofibers of PHA-b-PEO were obtained. Electrospinning of aqueous suspensions of biodegradable polyesters alleviates concerns regarding safety, toxicology and environmental problems, which are associated with spinning of such polyesters from harmful organic solvents and thereby offers novel perspectives for applications in medicine, pharmacy and agriculture. Electrospinning of polymers from aqueous suspensions avoiding harmful organic solvents is suggested to be "green electrospinning".
