Microcapsule/nanocapsule and encapsulation techniques have great potential for devices Of functional materials. Also, electrospinning has attracted great attention for the fabrication Of microstructures and nanostructures. The fluidity after melting limits the application of phase-transformation thermochromic materials. In this study, with the melt coaxial electrospinning technique, a phase-transformation thermochromic material was encapsulated in poly(methyl methacrylate) nanofibers. A device of this phase-transformation thermochromic material was realized. With a poly(methyl methacrylate) shell with good optical transmission and a thermoresponsive core made of crystal violet lactone, bisphenol A, and 1-tetradecanol core, the fibers had good thermal energy management, fluorescent thermochromism, and reversibility. The fabrication of thermochromic core-shell nanofibers has further potential in the preparation of temperature sensors with good fluorescence signals and body-temperature calefactive materials with intelligent thermal energy absorption, retention, and release. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 412: 269-274, 2009