Polymeric Nanofibers from Rapid Expansion of Supercritical Solution

The use of the supercritical fluid technique, rapid expansion of a supercritical solution into a liquid solvent (RESOLV), to process polymers into nanofibers (less than 100 nm in diameter) is reported. It is found that the polymer concentration in the preexpansion supercritical solution plays a critical role in determining the dominating product morphology between nanoparticles and nanofibers. For the CO 2 -soluble poly(heptadecafluorodecyl acrylate) (PHDFDA), as an example, the rapid expansion of the polymer solutions in supercritical CO 2 with low and high PHDFDA concentrations into an ambient aqueous NaCl solution produces exclusively nanoparticles and nanofibers, respectively. The RESOLV processing of poly(methyl methacrylate) (PMMA) and biodegradable polymer poly( l -lactic acid) (PLA) in supercritical CO 2 −cosolvent system into nanofibers is also described and discussed.