Covalent bonding of photochromic molecules to a polymer matrix, flexibility of the polymeric host, and also its nanofibrous state are appropriate conditions to enhance the switching rate, photofatigue resistance, sensitivity, and long-term performance of these photo-active groups. Herein, photoresponsive polymethyl methacrylate and poly(methyl methacrylate-cobutyl acrylate) chemically modified with spiropyran (MSP and MBSP, respectively) were prepared through emulsion polymerization. To improve photosensitivity and reduce response time, the corresponding nanofibers (MSP@NF and MBSP@NF) were prepared by an electrospinning technique. Smooth and beadless morphology, high porosity (above 85%), and uniform diameter size distribution of MSP@NF (169 ± 39 nm) and MBSP@NF (203 ± 47 nm) were identified. Time-dependent UV−vis spectra and photo-isomerization kinetics revealed that flexible MBSP@NF has remarkable enhancement in the SP to merocyanine isomerization rate (19 folds) relative to the corresponding film. Reversible responsivity to HCl and ammonia vapors showed a dramatic color change and maximum absorption peak displacement for nanofiber samples immediately, together with fluorescence switching "on" and "off", while this took about 10 min for the MBSP@F sample. This was attributed to the high surface area and porous structure of these nanofibers, providing enhanced diffusion and interaction with the photo-active groups. Reversible optical write−erase cycles with improved response time and color intensity approved photopatterning capability of MBSP@NF. Enhanced photochemical, photostability, and photofatigue resistance of MBSP@NF within 10 cycles of alternating exposure to HCl−ammonia vapors and also UV−vis irradiations revealed the potentiality of such nanofibers in visual reversible photopatterning and optochemical acidochromic and ammonia-chromic portable probes.

Quick transfer of sweat from skin to atmosphere and dryness of textile inner surface are of scientific and commercial interests. However, creating a balance between these two parameters remains a serious challenge. In this work, electrospun double-layered membranes constructed of poly(vinylidene fluoride) fibrous layer (as inner hydrophobic layer) and nylon6 nanofibrous layer (as outer hydrophilic layer) are produced. Once a thin hydrophobic layer is considered, the enhanced water pulling mechanism is balanced out by increased wetted area in the inner surface. This is handled through selecting an optimum thickness for the inner layer. The designed double-layered membrane is a promising candidate for developing modern breathable textiles with enhanced moisture management properties such as sportswear.

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Photoswitchable nanofibers and nanocomposite fibers containing plasmonic nanoparticles have attracted a great deal of interest in optical and plasmonic devices. Herein, photoswitchable poly(methyl methacrylate-co-vinylimidazole-co-spiropyran ethyl acrylate) (MVSP) and its copolymer with butyl acrylate (MBVSP) were prepared via emulsion polymerization, and the corresponding nanofibers (MVSP@NF and MBVSP@NF) and nanocomposite fibers (MVSP/Au@NF and MBVSP/Au@NF) containing AuNRs were fabricated through electrospinning. FTIR and 1 H NMR analyses confirmed the progress of the copolymerization reaction. The morphology of the prepared nanofibers containing AuNRs with an aspect ratio of 2.5 was identified by SEM and TEM techniques. The inclusion of vinylimidazole into the copolymer chains resulted in well-dispersed AuNRs. Photoisomerization studies revealed a higher photochromic efficiency for MBVSP@F (reflective intensity of 37.4%) with respect to MVSP@NF (reflective intensity of 62.5%) because of the greater flexibility of the chains. In addition, the presence of AuNRs in the nanocomposite fibers with high absorptivity intensified the photochromic properties for both samples. The polarization-dependent plasmonic band of AuNRs was switched between 650 and 634 nm through the photoisomerization of nonpolar SP to polar MC reversibly for MVSP/Au@NF. This displacement was just 4 nm for MBVSP/ Au@NF, owing to the limited coupling between AuNRs and MC isomers. Besides, the capability of both nanocomposite fibers for reversible optical patterning was investigated by fast write−erase cycles. Enhanced photofatigue resistance in those fibers and the photomodulation of the plasmonic band of AuNRs using SP to MC isomerization revealed their promising potential for optical patterning and on-demand real-time plasmonic devices.