Recently, solid-state optical nanostructures, which can be promising materials for diverse applications, have been extensively studied.[1] Quantum-dot and organic-dye impregnated nanocomposites have been fabricated by several research groups. [2] In the case of the organic-dye impregnated nanocomposites, the nanoconfined organic dyes might undergo an energy transfer, resulting in the enhancement of the fluorescent signal at low dye concentrations. [3,4] Wang and Tan fabricated silica nanoparticles encapsulated by three organic dyes. They suggested that the fluorescence resonance energy transfer (FRET)-mediated emission characteristics could be tuned using single wavelength excitation by varying the doping ratio of the three tandem dyes.[4]FRET has been extensively studied theoretically and in practical applications, especially in emitting layers for lightemitting diodes (LEDs).[5] Energy-transfer procedures, such as Förster energy transfer and Dexter energy transfer, add additional benefits for improving the emitting performance of LEDs and lasers, and for producing beam modulators with a high Stokes shift, and so forth. [6] Most investigations related to energy transfer have been conducted using chromophoreembedded thin films due to the distance-dependent character of the energy transfer between the donor and the acceptor. [7] In addition, chromophores confined to nanometer dimensions, such as micelles, mesoporous silica or carbon, and zeolites, have also been investigated concerning the energy-transfer system.[8]Organic-dye embedded polymer nanocomposites have attracted much attention because of their biocompatibility, facile preparation, and diverse functionality. [9,10] Whilst organic dye/polymer nanocomposites have their advantages, to the best of our knowledge, there has been no report concerning the fabrication of polymer nanofibers embedded with multiple organic dyes for FRET applications.We report on the fabrication of organic-dye embedded polymer nanofibers via vapor deposition polymerization (VDP) and subsequent dipping in organic dye solution using an anodic aluminum oxide (AAO) membrane. Having demonstrated the feasibility of this technique for FRET applications, we were prompted to embed photoluminescent dyes, such as coumarin 6 (Cm6) and rhodamine B (RhB), into poly(methyl methacrylate) (PMMA) and observed the FRET properties in this system.The overall synthetic procedure of organic-dye embedded PMMA nanofibers is illustrated in Scheme 1. The porous AAO membrane with a pore diameter of 100 nm and a thickness of 60 lm was placed in a reaction vessel equipped with a sealing apparatus and monomer loading reservoir. The reaction chamber was evacuated until the vacuum pressure reached 10 -2 Torr (1 Torr = 133.322 Pa). Then, a heptane solution containing 2,2-azo-bis-(2,4-dimethylvaleronitrile) was injected into the vessel as a radical initiator. The AAO membrane was wetted by the radical initiator solution. Consecutively, the MMA monomer was introduced and the reaction chamber was kept at 70°C for 6 h. ...
