Effect of neat and reinforced polyacrylonitrile nanofibers incorporation on interlaminar fracture toughness of carbon/epoxy composite

This paper presents an experimental investigation on fracture behavior of epoxy resin-carbon fibers composites interleaved with both neat polyacrylonitrile （PAN） nanofibers and A1203-PAN nanofibers. In particular, the paper focuses on the effect of adding Al2O3 nanopartiles in PAN nanofibers, which were incorporated in unidirectional （UD） laminates. The effectiveness of adding a thin film made of Al2O3-PAN on the fracture behavior of the carbon fiber reinforced polymer （CFRP） has been addressed by comparing the energy release rates, obtained by testing double cantilever beam （DCB） samples under mode I loading condition. A general improvement in interlaminar fracture energy of the CFRP is observed when the both neat PAN nanofibers and Al2O3-PAN nanofibers are interleaved. However, higher interlaminar strength has been observed for the samples with a thin film of Al2O3-PAN nanofibers, suggesting a better stress distribution and stress transformation from resin-rich area to reinforcement phase of hybrid composites.

Assembly of CdS Nanowires from Solution Using Oriented Nanofibers

This paper presents an universal assembly approach,based on the oriented nanofibers,for the formation of large-scale ordered nanowire arrays.First,CdS NWs solution is dripped onto the substrate surface.Second,before the CdS NWs solution evaporates,the oriented nanofibers slides along the substrate surface to assemble the CdS nanowires.The mechanism involving ordered alignment of nanowires on the substrate surface was investigated based on our experimental results.The resulting nanowires arrays can be further used for the creation of massive nanoelectronic-device arrays.

Recent advances in novel aerogels through the hybrid aggregation of inorganic nanomaterials and polymeric fibers for thermal insulation

Aerogel is a nanoporous solid material with ultrahigh porosity,ultralow density,and thermal conductivity,which is considered to be one of the most promising high-performance insulation materials today.However,traditional pure inorganic aerogels(i.e.,silica aerogel)exhibit inherent structural brittleness,making their processing and handling difficult,and their manufacturing costs are relatively high,which limits their large-scale practical use.The recently developed aerogel based on polymer nanofibers has ultralow thermal conductivity and density,excellent elasticity,and designable multifunction.More importantly,one-dimensional polymer nanofibers are directly used as building blocks to construct the network of aerogels via a gelation-free process.This greatly simplifies the aerogel preparation process,thereby bringing opportunities for large-scale aerogel applications.The aggregation of inorganic nanomaterials and polymer nanofibers is considered to be a very attractive strategy for obtaining highly flexible,easily available,and multifunctional composite aerogels.Therefore,this review summarizes the recent advances in novel aerogels through the hybrid aggregation of inorganic nanomaterials and polymeric fibers for thermal insulation.The main processing routes,porous microstructure,mechanical properties,and thermal properties and applications of these aerogels are highlighted.In addition,various future challenges faced by these aerogels in thermal insulation applications are discussed in this review.

Filtration of fine particles in atmospheric aerosol with electrospinning nanofibers and its size distribution

In this study, the size distribution of atmospheric aerosol in Beijing was monitored by the scanning mobility particle sizer spectrometer and the optical particle sizer. The size of particles in atmospheric aerosol was primarily distributed in the range of less than 1 pm. It showed different changes with the mass concentrations of particulate matters with an aerodynamic diameter of 〈2.5 pm （PM2.5） for different sizes of fine particles. The amount of ultrafine particles （less than about 60 nm） decreased while the larger ones （〉60 nm） increased along with the mass concentration of PM2.5 in atmospheric aerosol. This was be- cause of the formation of the secondary atmospheric aerosol. The polylactic acid （PLA） nanofibers were prepared for filtering the aerosol by electrospinning. PLA nanofiber mats were used as the middle layer to design the composite filter membranes. Atmospheric aerosol was used as dust source in the filtration test. The results showed that the filtration efficiency of the com- posite filter media increased along with the thickness of nanofiber mats, which was controlled by the collection time during electrospinning. Filtration efficiency can be improved obviously by compositing with a thin layer of nanofibers.

Functionalized polymer nanofibers: a versatile platform for manipulating light at the nanoscale

As an organic optical fiber with a diameter comparable to or less than the wavelength of light,polymer nanofibers have been attracting increasing attention as a platform for manipulating light at the nanoscale.A variety of applications for polymer optical nanofibers,including waveguides,light sources and sensors,have been reported in recent years.In this article,the recent progress in the field of polymer optical nanofibers is reviewed in terms of their fabrication,characterization and applications.In particular,we focus on functionalized polymer nanofibers doped with functional materials,such as dye molecules,noble metal nanoparticles,quantum dots and rare earth ions,which greatly expand their capabilities of generating,propagating,converting and modulating light at the nanoscale.

One-pot synthesis of hierarchical CoS/NC@MoS/C hollow nanofibers based on one-dimensional metal coordination polymers for enhanced lithium and sodium-ion storage

Multicomponent metal sulfides have been recognized as promising anode materials for lithium/sodiumion storage given their enticing theoretical capacities. However, the simplification of synthetic processes and the construction of heterogeneous interfaces of multimetal sulfides remain great challenges. Herein,a hierarchical 1T-MoS2/carbon nanosheet decorated Co1–xS/N-doped carbon(Co1–xS/NC@MoS2/C) hollow nanofiber was designed and constructed via a one-pot hydrothermal method using a cobalt-based coordination polymer nanofiber. This nanofiber can transform in-situ into conductive N-doped carbon hollow fibers embedded with active Co1–xS nanoparticles, enabling the epitaxial growth of MoS2 nanosheets.Consequently, the Co1–xS/NC@MoS2/C composites achieve exceptional lithium/sodium-ion storage performance. Compared to MoS2/C microspheres and Co1–xS/NC hollow nanofibers alone, the Co1–xS/NC@MoS2/C hollow nanofibers deliver higher discharge capacities(1085.9 mAh g^-1 for lithium-ion batteries(LIBs) and 748.5 mAh g^-1 for sodium-ion batteries(SIBs) at 100 mA g^-1), better capacity retention(910 mAh g^-1 for LIBs and 636.5 mAh g^-1 for SIBs after 150 cycles at 100 mA g^-1), and increased cycling stability(407.2 mAh g^-1 after 1000 cycles for SIBs at 1000 m A g^-1). Furthermore, the kinetic analysis shows that the lithium/sodium-ion storage processes of the Co1–xS/NC@MoS2/C electrode are mainly controlled by pseudocapacitance behavior. The excellent electrochemical properties can thus be ascribed to the synergy of the MoS2/C nanosheets with the enlarged interlayer spacing, good conductivity of the carbon layers, and the Co1–xS nanoparticles embedded in the hollow nanofibers with extensive reaction sites.

Electroactive polymeric nanofibrous composite to drive in situ construction of lithiophilic SEI for stable lithium metal anodes

Uncontrolled lithium dendrite growth hinders the practical application of lithium metal batteries(LMBs).Herein,we report a novel Li^(+) flux distributor achieved by placing an electroactive polyvinylidene fluoride/polymethyl methacrylate(PVDF/PMMA)composite nanofiber interlayer on a current collector,inducing uniform lithium deposition to mitigate the dendrite problem.Specifically,the released PMMA reacts with Liþto form abundant C–O–Li bonds and generate in situ a stable lithiophilic PMMA-Li solid electrolyte interphase layer.Theoretical calculations reveal that polar C–F groups in the PVDF framework and lithiophilic PMMA-Li provide homo-dispersed Li^(+) migration pathways with low energy barriers.Consequently,uniform Li nucleation is achieved at the molecular level,resulting in ultrahigh cycling stability with dendrite-free Li deposition at 5 mA cm^(-2) and 5 mAh cm^(-2)for over 500 h.The PVDF/PMMA||Li||LiFePO_(4)(LFP)full cell presents an increased rate capacity of 110 mAh g^(-1) at 10 C.In addition,a soft-package battery demonstrates a high energy density of 289 Wh kg^(-1).This work provides a facile design for stable lithium metal anodes to promote the practical use of LMBs and other alkali metal batteries.