ELECTROSPINNING OF ULTRA-THIN POLYMER FIBERS

The electrospinning technique was used to spin ultra-thin fibers from several polymer/solvent systems. The diameter of the electrospun fiber s ranged from 16 nm to 2 mu m. The morphology of these fibers was inve stigated with an atomic force microscope (AFM) and an optical microsco pe. Poly(ethylene oxide) (PEO) dissolved in water or chloroform was st udied in greater detail. PEO fibers spun from aqueous solution show a ''beads on a string'' morphology. An AFM study showed that the surface of these fibers is highly ordered. The ''beads on a string'' morpholo gy can be avoided if PEO is spun from solution in chloroform; the resu lting fibers show a lamellar morphology. Polyvinylalcohol (PVA) dissol ved in water and cellulose acetate dissolved in acetone were additiona l polymer/solvent systems which were investigated. Furthermore, the el ectrospinning process was studied: different experimental lay-outs wer e tested, electrostatic fields were simulated, and voltage-current cha racteristics of the electrospinning process were recorded.