e Spiropyran-functionalized poly(methyl methacrylate) (PMMA) Forcespinning® fibers were fabricated using a fiber making machine of our own design, employing 1 0 ,3 0 ,3 0 -trimethyl-6-nitrospiro[1(2H)-benzopyran-2,2 0 -indoline] (6-nitro BIPS) as the spiropyran. The effects of the polymer solution concentration (and hence the viscosity), the spinneret rotational rate, and the internal needle diameter on the formation and morphology of the fibers were examined, using scanning electron microscopy. A rotational speed of 3000 rpm and an internal nozzle diameter of 0.35 mm (23 G) in conjunction with a polymer concentration of 15 wt% produced 6-nitro BIPS/PMMA Forcespinning fibers having a smooth morphology with no beads. The photochromic properties of the resultant fibers were characterized by reflectance spectroscopy using the Kubelka-Munk function, fluorescence excitation emission matrix (EEM) analysis, and Raman spectroscopy. The thermal decoloration dynamics of the 6-nitro BIPS in the PMMA fibers were in good agreement with the properties observed in films. These results suggest that 6-nitro BIPS and other spiropyran dyes have significant potential as probes to assess the structures of micro/nanofibers.

Polystyrene (PS)-based composite microfibers combined with a photochromic spiropyran dye, 1,3,3-trimethylindolino-6'-nitrobenzopyrylospiran (6-nitro BIPS), and a photostimulable phosphor, europium-doped barium fluorochloride (BaFCl:Eu), were developed for the detection of X-ray exposure doses on the order of approximately 1 Gy. To produce the PS-based composite microfibers, we employed a forcespinning method that embeds a high concentration of phosphor in PS in a safe, inexpensive, and simple procedure. On the basis of the optimization of the forcespinning process, fibrous color dosimeters with a high radiation dose sensitivity of 1.2-4.4 Gy were fabricated. The color of the dosimeters was found to transition from white to blue in response to X-ray exposure. The optimized fibrous color dosimeter, made from a solution having a PS/6-nitro BIPS/BaFCl:Eu/CCl ratio of 7.0/0.21/28.0/28.0 (wt %) and produced with a 290 mm distance between the needle and collectors, a 0.34 mm 23 G needle nozzle, and a spinneret rotational rate of 3000 rpm, exhibited sensitivity to a dose as low as 1.2 Gy. To realize practical applications, we manufactured the optimized fibrous color dosimeter into a clothlike color dosimeter. The clothlike color dosimeter was mounted on a stuffed bear, and its coloring behavior was demonstrated upon X-ray exposure. After exposure with X-ray, a blue colored and shaped in the form of the letter "[Formula: see text]" clearly appeared on the surface of the clothlike color dosimeter. The proposed fibrous color dosimeters having excellent workability will be an unprecedented dosimetry and contributed to all industries utilizing radiation dosimeters. This new fibrous "composite resin dosimeter" should be able to replace traditional, wearable, and individual radiation dose monitoring devices, such as film badges.

A polystyrene (PS)-based composite resin dosimeter (CRD) film comprising 2-(phenylamino)-6-(dipentylamino)-3-methylspiro[9 H -xanthene-9,3′-phthalide] (Black305) fluoran leuco dye, cerium-doped yttrium aluminum perovskite YAlO 3 :Ce (YAP:Ce) scintillator, and 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine (MBTT) photoacid generator was developed for the visualization of X-ray exposure doses in the range of 18–170 Gy. The color of the CRD film changed from yellow to black within this range based on the X-ray exposure dose. A CRD film based on Black305/YAP:Ce/MBTT/PS could be used to produce a dosimeter with various color change sensitivities by controlling the thermodynamic parameters of the constituent materials. A CRD film is a promising tool for measuring the X-ray exposure dose and can be used as an alternative to the existing radiochromic dosimeters.

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