Nanofibers from Melt Blown Fiber-in-Fiber Polymer Blends*

Nanofibers were generated by melt blowing three sets of polymer blends each comprised of pairs of immiscible components. Blends containing minority phases of poly(ethylene-\textit{co}-chlorotrifluoroethylene) (PECTFE) in poly(butylene terephthalate) (PBT), PECTFE in poly(styrene) (PS), and PBT in PS, were melt blown into long (\textgreater 100 microns) fibers with average diameters of several microns. Electron microscope revealed that melt blowing transformed the initial spherical dispersions into a nanofibers-in-fiber morphology. Macroscopic mats of nonwoven PBT and PECTFE nanofibers, with average diameters as small as 70 nm, were isolated by selectively removing the majority phase with a solvent. This method provides a potentially inexpensive, high throughput, one step route to scalable quantities of polymeric nanofibers.