Supercritical CO2-assisted electrospinning

Polymer fibers of high molecular weight polydimethylsiloxane (PDMS) and poly (d,l-lactic acid) (PLA) were produced using only electrostatic forces and without the use of a liquid solvent. The fibers were formed between two electrodes in a high-pressure view cell. A polymer sample was placed on a grounded electrode and a second, counter electrode was placed at high potential. The polymer was observed as the thermodynamic conditions (e.g. temperature, CO2 pressure) and potential difference were varied. At a CO2 temperature and pressure above the critical point, but well below the single-phase region, polymer fibers formed between the grounded electrode and the high voltage counter electrode. It is surmised that the supercritical CO2 reduces the polymer viscosity sufficiently to allow fibers to be electrostatically pulled from an un-dissolved bulk polymer sample.