simplicity of design. [10,11] Several requirements such as high stretchability, flexibility, a wide working strain range from a subtle region to a large region, durability, lightweight, and low energy consumption should be fulfilled for wearable devices. [12] To achieve the stretchable flexible devices, studies on stretchable elastomeric substrates consisting of highly conductive fillers have been reported. [13,14] Ding et al. demonstrated a scalable and facile preparation of the electrospun polyurethane (PU) nonwoven dip-coated with the conducting polymer poly(3,4-ethylened ioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), which possessed adjustable electrical conductivity in the range of 30-200 S m −1 and large stretchability of 400%. [15] Lu et al. reported a sandwich-structured strain sensor with a gauge factor (GF) of 12.9 (at 20% strain) and a sensing range of 0-50% based on attaching the silver nanowires (AgNWs) on the thermoplastic polyurethane electrospun membrane (TPUEM) by filtration, followed by spin-coating using the liquid polydimethylsiloxane (PDMS). [16] Recently, electrospinning has become an effective, facile, and scalable technique for preparation of micro/nanofibers applied in wide applications. [17][18][19] The electrospun fibers own numerous advantages such as large specific surface area, high porosity, fine diameter, and commendable mechanical flexibility, which is an ideal base material for functional composites. [20,21] Especially, thermoplastic polyurethane (TPU) was easily electrospun into fibrous membrane which displayed outstanding stretchability, flexibility, and mechanical strength. [22,23] However, the pristine TPUEM has no conductivity and cannot be serving as sensing materials solely. Diverse conductive fillers incorporate into TPUEM to be developed as stretchable strain sensors. Yan et al. fabricated electrospun TPU fiber yarns successively decorated with multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) for wearable strain sensors. [24] Wang et al. developed a novel strain sensor with an excellent 3D conductive network based on reduced graphene oxide (RGO)-decorated TPU mats. [25] Tian fabricated electrospun PU/polyaniline nanofibrous mat by in situ chemical polymerization of aniline monomers on the surface of electrospun PU nanofiber substrate for wearable device. [26] However, it is quite difficult to Highly stretchable, conductive, and sensitive strain-sensing materials have aroused wide interest owing to their potential in wearable devices. A facile and scalable method to fabricate a carbon-nanotube-(CNT-) bridged silver nanoparticles (AgNPs) strain sensor based on thermoplastic polyurethane electrospun membrane (TPUEM), which exhibits a large strain range with a high gauge factor simultaneously, is demonstrated. It exhibits a high stretchability with large workable strain range of up to 550%, high gauge factor of 7066, good durability over 1000 cycles, and comparable stability under various strains. Importantly, it can be used for human mo...

TitleCoaxial electrospun cellulose-core fluoropolymer-shell fibrous membrane from recycled cigarette filter as separator for high performance lithium-ion battery Permalink https://escholarship.org/uc/item/9gc5x56wJournal ACS Sustainable Chemistry and Engineering, 3(5)

Polyacrylonitrile (PAN) nanofibers were prepared by electrospinning and they were modified with hydroxylamine to synthesize amidoxime polyacrylonitrile (AOPAN) chelating nanofibers, which were applied to adsorb copper and iron ions. The conversion of the nitrile group in PAN was calculated by the gravimetric method. The structure and surface morphology of the AOPAN nanofiber were characterized by a Fourier transform infrared spectrometer (FT-IR) and a scanning electron microscope (SEM), respectively. The adsorption abilities of Cu2+ and Fe3+ ions onto the AOPAN nanofiber mats were evaluated. FT-IR spectra showed nitrile groups in the PAN were partly converted into amidoxime groups. SEM examination demonstrated that there were no serious cracks or sign of degradation on the surface of the PAN nanofibers after chemical modification. The adsorption capacities of both copper and iron ions onto the AOPAN nanofiber mats were higher than those into the raw PAN nanofiber mats. The adsorption data of Cu2+ and Fe3+ ions fitted particularly well with the Langmuir isotherm. The maximal adsorption capacities of Cu2+ and Fe3+ ions were 215.18 and 221.37 mg/g, respectively.

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