Table of Contents:
Water stable and biodegradable nanofibers were successfully prepared by Green Electrospinning of concentrated, tenside-free, aqueous dispersions of amphiphilic block copolymers consisting of a hydrophobic aliphatic polyester block and a hydrophilic MPEG block.
The 16 wt% aqueous dispersions of aliphatic polyester-block-MPEG were prepared by Solvent Displacement method followed by dialysis. Depending on the aliphatic polyester-to-MPEG-ratio the particle sizes of the dispersions were in the range of 40-250 nm.
The obtained dispersions were processed to nanofibers by Green Electrospinning adding poly(ethylene oxide) and poly(vinyl alcohol) as template polymers. The influence of the particle size of the polymer, as well as the amount, molecular weights and kind of the template polymer on the electrospinnability were investigated. Furthermore the water stability, structure and mechanical properties of the fibers were analyzed. In doing so electrospinning of high molecular weight PEO and longer polyester blocks gave best results in terms of bead-free and smooth fibers.
In a second approach a new organic solvent free method for the electrospinning feed preparation were described by melting the polymer in water and adding the PEO as template polymer to the obtained emulsion. This Melt Dispersion method resulted in high viscous electrospinning feeds. The influence on the viscosity of the block copolymer as well as the amount and molecular weight of template polymer were investigated. The electrospinnability and the water stability of the fibers - compared to the Solvent Displacement based electrospinning feeds - were analyzed as well.
The capability of these aliphatic polyester-block-MPEGs as drug carrier system was investigated using propofol, a pheromone and PEI-DNA complexes as additives. The presences of the additives in the fibers were confirmed by 1H-NMR spectroscopy. The release rate was detected by measuring an isothermal TGA.