Nanofibers were prepared from water-extractable melt-blown immiscible polymer blends containing a commercial sulfopolyester (SP) as the sacrificial phase. Application of the water-dispersible SP eliminates issues associated with organic solvents, providing a facile, economic, and environment-friendly approach to high throughput fabrication of melt-blown nanofibers with an average diameter as small as 66 nm. Moreover, this approach offers a new route to prepare multilayer melt-blown nano-/micro-fiber composites. We demonstrate the fabrication of porous double-layer melt-blown PBT nano-/micro-fiber composites by tuning the collection time of the melt-blown SP/PBT blend fibers. Such materials are potentially useful for filtration media. (C) 2016 Elsevier Ltd. All rights reserved.