One-dimensional Fiber Research Articles

A note on flatness of some fiber type contractions

We discuss the flatness property of some fiber type contractions of complex smooth projective varieties of arbitrary dimensions. We relate the flatness of some morphisms having one-dimensional fibers with their conic bundles structures, also in the general case in which some mild singularities of the varieties are admitted.

Sound from aeroelastic vortex-fibre interactions.

The motion of a line vortex moving past a one-dimensional flexible fibre is examined theoretically. A Schwarz-Christoffel conformal mapping enables the analytical solution of the potential flow field and its hydrodynamic moment on the flexible fibre, which is composed of a rigid segment constrained to angular motions on a wedge. The hydroelastic coupling of the vortex path and fibre motion affects the noise signature, which is evaluated for the special case of acoustically compact fibres embedded in a half plane. Results from this analysis attempt to address how the coupled interactions between vortical sources and flexible barbules on the upper surface of owl wings may contribute to their acoustic stealth. The analytical formulation is also amenable to application to vortex sound prediction from flexible trailing edges provided that an appropriate acoustic Green's function can be determined. This article is part of the theme issue 'Frontiers of aeroacoustics research: theory, computation and experiment'.

Wettability Control in Tree Structure-Based 1D Fiber Assemblies for Moisture Wicking Functionality.

One of the fundamental properties of natural systems is their water transport ability, and living systems have efficient moisture management features. Here, a unique structure, inspired by the water transfer behavior in trees, was designed for one-dimensional (1D) fiber assemblies. In this 1D fiber assembly structure, a differential capillary effect enabling rapid water transfer at the interface between traditional cotton fibers and electrospun nanofibers was explored. A tree-like structure yarn was constructed successfully by novel electrospinning technology, and the effect was quantitatively controlled by precisely regulating the fibers' wettability. Fabrics based on these tree-like core-spun yarns possessed advanced moisture-wicking performance, a high one-way transport index (R) of 1034.5%, and a desirable overall moisture management capability of 0.88, which are over two times higher than those of conventional fabrics. This moisture-wicking regime endowed these 1D fiber assemblies with unique water transfer channels, providing a new strategy for moisture-heat transmission, microfluidics, and biosensor applications.

Design of Ethylene-Vinyl Acetate Copolymer Fiber with Two-Way Shape Memory Effect.

One-dimensional shape memory polymer fibers (SMPFs) have obvious advantages in mechanical properties, dispersion properties, and weavability. In this work, a method for fabricating semi-crystallization ethylene-vinyl acetate copolymer (EVA) fiber with two-way shape memory effect by melt spinning and ultraviolet (UV) curing was developed. Here, the effect of crosslink density on its performance was systematically analyzed by gel fraction measurement, tensile tests, DSC, and TMA analysis. The results showed that the crosslink density and shape memory properties of EVA fiber could be facilely adjusted by controlling UV curing time. The resulting EVA fiber with cylindrical structure had a diameter of 261.86 ± 13.07 μm, and its mechanical strength and elongation at break were 64.46 MPa and 114.33%, respectively. The critical impact of the crosslink density and applied constant stress on the two-way shape memory effect were analyzed. Moreover, the single EVA fiber could lift more than 143 times its own weight and achieve 9% reversible actuation strain. The reversible actuation capability was significantly enhanced by a simple winding design of the single EVA fiber, which provided great potential applications in smart textiles, flexible actuators, and artificial muscles.

Seeded Polymerization of an Amide-Functionalized Diketopyrrolopyrrole Dye in Aqueous Media.

The self-assembly of an amide-functionalized dithienyldiketopyrrolopyrrole (DPP) dye in aqueous media was achieved through seed-initiated supramolecular polymerization. Temperature- and time-dependent studies showed that the spontaneous polymerization of the DPP derivative was temporally delayed upon cooling the monomer solution in a methanol/water mixture. Theoretical calculations revealed that an amide-functionalized DPP derivative adopts an energetically favorable folded conformation in the presence of water molecules due to hydration. This conformational change is most likely responsible for the trapping of monomers in the initial stage of the cooperative supramolecular polymerization in aqueous media. However, the monomeric species can selectively interact with externally added fragmented aggregates as seeds through concerted π-stacking and hydrogen-bonding interactions. Consequently, the time course of the supramolecular polymerization and the morphology of the aggregated state can be controlled, and one-dimensional fibers that exhibit a J-aggregate-like bathochromically shifted absorption band can be obtained.

In-situ preparation of nitrogen-doped carbon-modified lithium vanadium phosphate fibers with mesoporous nanostructure for lithium energy storage

Abstract To significantly enhance the lithium storage performance of lithium vanadium phosphate (Li3V2(PO4)3), nitrogen-doped carbon-modified Li3V2(PO4)3 fibers with mesoporous structure have been designed and prepared for the first time via a simple electrospinning technology. The obtained results demonstrate that the nanosized Li3V2(PO4)3 crystals (10–25 nm) are embedded into the one-dimensional carbon fibers. Meanwhile, the electrochemical tests indicate that the prepared electrode possesses outstanding rate performance for energy storage with a high capacity of 129.2 mAh g−1 over 400 cycles at 20 C. The good battery property can be attributed to the nanosized crystals and conductive mesoporous carbon nanofibers, which can decrease the Li+ diffusion pathway and improve the apparent conductivity of the active material.

Through-thickness thermal conductivity enhancement of carbon fiber composite laminate by filler network

This paper successfully introduces highly conductive filler network in composite laminate to enhance its through-thickness thermal conductivity (TC). The effects of filler type, filler content, filler dimension, and ply scheme on through-thickness TC are investigated. The results show that one-dimensional carbon fiber fillers occupy both interlaminar and inter-tow regions forming the river-pattern conductive network inside the modified composite. Hence, the through-thickness TC is enhanced effectively up to 2.21 W·m−1 K−1 for the carbon fiber filler modified composite, which increases with increasing filler content. The composites modified by shorter fiber fillers show higher through-thickness TCs than those modified by long fillers, due to relatively higher content of shorter fillers in inter-tow gap, easy orientation along through-thickness direction and higher filler volume faction in conductive path. These results prove the superiority of continuous conductive network with concentrated fillers, and guide the structural design of composite laminate to manage its through-thickness TC.

Highly Sensitive, Selective, and Flexible NO2 Chemiresistors Based on Multilevel Structured Three-Dimensional Reduced Graphene Oxide Fiber Scaffold Modified with Aminoanthroquinone Moieties and Ag Nanoparticles.

Highly sensitive, selective, and room-temperature-performing gas sensors have always been the pursuit in the sensing field for practical applications. However, the existing gas sensors can seldom satisfy the aforementioned requirements. Here, we integrate zero-dimensional Ag nanoparticles (AgNPs), one-dimensional polymer fibers, and two-dimensional aminoanthroquinone-functionalized reduced graphene oxide (AQRGO) sheets into a three-dimensional sensing scaffold (AgNP-3D-AQRGO) for high-performance NO2 sensing. The AQ moieties and AgNPs are decorated onto the RGO sheets through a wet chemical route. Electrospinning and self-assembly techniques are employed to assemble the polymer fibers and the functional RGO sheets into a three-dimensional scaffold. The resulting AgNP-3D-AQRGO-based gas sensor can perform at room temperature and exhibits excellent sensing performance for NO2, including an ultrahigh sensitivity (10.3 ppm-1), an ultralow limit of detection (0.6 ppb), and an extremely remarkable selectivity to solely NO2 molecules. Furthermore, the sensor is also highly flexible, demonstrating great potential for portable and real-time monitoring of toxic gas in personal mobile electronics.

Preparation of urchin-like carbon fibers/AlSi12 and their growth mechanism investigation

Abstract In this paper, urchin-like carbon fibers/AlSi12 (CFs/AlSi12) are synthesized by in-situ growth of one-dimensional carbon fibers on the surface of AlSi12 microspheres. Copper metal catalyst for the growth of carbon fibers is inlaid within microcracks and micropores on the surface of AlSi12 microspheres, which are produced by corrosion via hydrochloric acid and subsequent displacement reaction between aluminum and copper dichloride. For subsequent chemical vapor deposition (CVD), argon/hydrogen gas and acetylene are used as pretreatment gas and carbon source, respectively. Lots of carbon fibers are formed on the surface of AlSi12 microspheres, and urchin-like CFs/AlSi12 are obtained finally. In addition, the growth mechanism of urchin-like CFs/AlSi12 is discussed briefly.

Contractions and deformations

Suppose that f is a projective birational morphism with at most one-dimensional fibres between d-dimensional varieties X and Y , satisfying Rf∗OX = OY . Consider the locus L in Y over which f is not an isomorphism. Taking the scheme-theoretic fibre C over any closed point of L, we construct algebras Afib and Acon which prorepresent the functors of commutative deformations of C, and noncommutative deformations of the reduced fibre, respectively. Our main theorem is that the algebras Acon recover L, and in general the commutative deformations of neither C nor the reduced fibre can do this. As the d = 3 special case, this proves the following contraction theorem: in a neighbourhood of the point, the morphism f contracts a curve without contracting a divisor if and only if the functor of noncommutative deformations of the reduced fibre is representable.

Insights into a novel class of azobenzenes incorporating 4,6-O-protected sugars as photo-responsive organogelators.

A novel class of 4,6-O-butylidene/ethylidene/benzylidene β-d-glucopyranose gelator functionalized with photo-responsive azobenzene moieties were designed and synthesized and also characterized using different spectral techniques. These azobenzene-based organogelators can gel even at lower concentrations (critical gelation concentration – 0.5% and 1%). A morphological study of the gels shows one-dimensional aggregated bundles and helical fibres. The main driving force for the self-assembly is through cooperative interactions exhibited by the different groups viz., sugar hydroxyl (hydrogen bonding interaction), azobenzene (aromatic π–π interaction) and alkyl chain of the protecting group (van der Waals interaction).

Synergistic improvement of electrical and thermal conductivities of carbon-based nanocomposites and its prediction by Mori-Tanaka scheme with interfacial resistances

Carbon-based nanomaterials have widely been used to enhance the thermal and electrical properties of polymer composites with the aid of miniaturization of electronic devices that require fast heat dissipation and electromagnetic interference shielding at a desired level. A combination of different carbon nanofillers can lead to a strong synergistic effect by creating the electron hopping pathway and conductive network. Here, we fabricate the hybrid nanocomposites composed of two-dimensional graphite nanoplatelets, one-dimensional microscale carbon fibers, and one-dimensional nanoscale multiwalled carbon nanotubes. The synergistic improvement of electrical and thermal conductivities of the hybrid nanocomposites is achieved by a three-dimensional network formation among the microscale and nanoscale fillers. A Mori-Tanaka averaging scheme with perfect and imperfect interfacial resistances under uni-directional and random fiber orientations is presented to predict the synergistic improvement of thermal conductivity of the nanocomposites. A transient temperature response in the nanocomposites is investigated to evaluate heat dissipation capability in which heat transfer rate is enhanced in the case of hybrid nanocomposites. Finite element simulation results are in a good agreement with the transient temperature response experimentally obtained.

PANI coated microporous graphene fiber capable of subjecting to external mechanical deformation for high performance flexible supercapacitors

Graphene based composites have been recognized as one of the most important classes of free-standing electrodes for supercapacitors. Herein, one-dimensional microporous graphene oxide fiber (MG) was designed with polystyrene sulfonate (PSS) microspheres as hard-template through a simple mass production method. The MG fiber exhibited outstanding flexibility and excellent tensile strength of 183.7 MPa. Then the polyaniline (PANI) coated microporous graphene (MGP) fibers were prepared by in-situ electropolymerization of aniline. Benefiting from the unique microporous structure, the optimized MGP fiber electrode exhibited remarkable electrochemical characteristics, such as highest specific capacitance of 36.95 mF/cm at current density of 0.25 mA/cm (204.2 F/cm3 at current density of 1.38 A/cm3), as well as excellent capacitance retention of 96.31% after 2000 cyclic voltammetry cycles. More than that, the MGP fiber electrode remained high retention rate of its initial specific capacitance even under tensile stress or bending, indicating its good tolerance to external damage.

Facile 1D graphene fiber synthesis from an agricultural by-product: A silicon-mediated graphenization route

A one-dimensional (1D) graphene fiber with a novel structure has been prepared by a heat treatment of rice husk, a natural by-product that contains high amounts of silica. A step-by-step heat treatment of rice husk revealed that (i) carbonization yields porous carbon and silica, (ii) 1D β-SiC nanowires are formed by the carbothermic reduction of silica, (iii) finally 1D graphene fibers are created by silicon sublimation from 1D β-SiC nanowires. Raman spectroscopy and electron microscopy studies revealed that the graphene fiber is composed of a turbostratic multilayer structure. The SiC-derived material exhibits a large crystalline size and turbostratic stacking making each layer as quasi-free-standing graphene, which is confirmed by the 3.9 times higher Raman G′-band intensity over the G-band intensity. Molecular dynamics simulations revealed a high diffusion rate of Si atoms and a volume reduction of the SiC structure at the sublimation temperature. Since the silicon sublimation occurred from multiple points of the SiC nanowire, this led to radially-collapsed fibers and faceted structures with thick-graphitic-layer that are inter-connected (deflated-balloons and inter-connected balloon-like fibers). This facile synthesis route opens up a new avenue to the cost-effective and etching-free production of self-standing graphene for its bulk usage.

Living Supramolecular Polymerisation of Perylene Diimide Amphiphiles by Seeded Growth under Kinetic Control.

The controlled solution self-assembly of an amphiphilic perylene diimide (PDI), with a hydrophobic perylene core and hydrophilic imide substituents with polydisperse oligo(ethylene glycol) (OEG) tethers is presented. It was possible, by a seeded-growth mechanism, to form colloidally stable, one-dimensional fibres with controllable lengths (from 400 to 1700 nm) and low dispersities (1.19-1.29) via a living supramolecular polymerisation process. Under the solvent conditions used, it was found that molecularly dissolved material (unimer) was present in samples of the fibre-like supramolecular assemblies. The free unimer may be present in a conformationally derived kinetically trapped state and/or may represent a more soluble PDI fraction with longer hydrophilic tethers. Significantly, it was also possible to form segmented supramolecular block copolymers by the addition of PDI unimer to chemically distinct PDI seeds, yielding fibres with controlled lengths. These results represent a significant advance in the ability to form PDI-based supramolecular polymers with precisely controlled lengths and architectures.

Polymorphism in Benzene-1,3,5-tricarboxamide Supramolecular Assemblies in Water: A Subtle Trade-off between Structure and Dynamics.

In biology, polymorphism is a well-known phenomenon by which a discrete biomacromolecule can adopt multiple specific conformations in response to its environment. The controlled incorporation of polymorphism into noncovalent aqueous assemblies of synthetic small molecules is an important step toward the development of bioinspired responsive materials. Herein, we report on a family of carboxylic acid functionalized water-soluble benzene-1,3,5-tricarboxamides (BTAs) that self-assemble in water to form one-dimensional fibers, membranes, and hollow nanotubes. Interestingly, one of the BTAs with the optimized position of the carboxylic group in the hydrophobic domain yields nanotubes that undergo reversible temperature-dependent dynamic reorganizations. SAXS and Cryo-TEM data show the formation of elongated, well-ordered nanotubes at elevated temperatures. At these temperatures, increased dynamics, as measured by hydrogen–deuterium exchange, provide enough flexibility to the system to form well-defined nanotube structures with apparently defect-free tube walls. Without this flexibility, the assemblies are frozen into a variety of structures that are very similar at the supramolecular level, but less defined at the mesoscopic level.

Biharmonic Riemannian submersions

In this paper, we study biharmonic Riemannian submersions. We first derive bitension field of a general Riemannian submersion, and we then use it to obtain biharmonic equations for Riemannian submersions with one-dimensional fibers and Riemannian submersions with basic mean curvature vector fields of fibers. These are used to construct examples of proper biharmonic Riemannian submersions with one-dimensional fibers and to characterize warped products whose projections onto the first factor are biharmonic Riemannian submersions.

Micrometre-long covalent organic fibres by photoinitiated chain-growth radical polymerization on an alkali-halide surface.

On-surface polymerization is a promising technique to prepare organic functional nanomaterials that are challenging to synthesize in solution, but it is typically used on metal substrates, which play a catalytic role. Previous examples on insulating surfaces have involved intermediate self-assembled structures, which face high barriers to diffusion, or annealing to higher temperatures, which generally causes rapid dewetting and desorption of the monomers. Here we report the photoinitiated radical polymerization, initiated from a two-dimensional gas phase, of a dimaleimide monomer on an insulating KCl surface. Polymer fibres up to 1 μm long are formed through chain-like rather than step-like growth. Interactions between potassium cations and the dimaleimide's oxygen atoms facilitate the propagation of the polymer fibres along a preferred axis of the substrate over long distances. Density functional theory calculations, non-contact atomic force microscopy imaging and manipulations at room temperature were used to explore the initiation and propagation processes, as well as the structure and stability of the resulting one-dimensional polymer fibres.

Superior piezoresistive strain sensing behaviors of carbon nanotubes in one-dimensional polymer fiber structure

The fabrication of piezoresistive strain sensor with unified and balanced properties of high sensitivity, stretchability, and durability still remains a great challenge due to the oversimplified thin film structure of strain sensor. In this work, a high-performance strain sensor based on conductive poly(styrene-butadiene-styrene)/carbon nanotube fiber (SBS/CNT fiber, SCF) was prepared via wet-spinning. Then, the morphology, mechanical property, piezoresistive performance and sensing mechanism of the SCF-based sensors were systematically investigated. The resultant SCF-based sensors simultaneously demonstrated superior sensitivity (with a gauge factor of 175 under 50% deformation), wide workable range (>260%) and excellent durability due to the excellent flexibility of SBS polymer (the breaking elongation of pure SBS fiber > 1300%), high conductivity of CNT (105 S/cm) and the strong π-π interaction between CNT and SBS. These properties make the composite fiber a perfect fit to monitor various large deformation in a wide range of applications. Moreover, the associated sensing mechanism was also systematically explained by tunneling theory and the evolution of the conductive network during the stretching-releasing process.

Durable superhydrophobic nanocomposite materials

The study of superhydrophobicity began with the observation and imitation of the superhydrophobic surface in nature. With the development of material characterization and fabrication techniques, more and more artificial superhydrophobic surfaces have been created, which show a broad prospect in application, such as self-cleaning, anti-icing, anti-fogging, anti-corrosion, oil-water separation and so on. The superhydrophobic surfaces in nature, including the leaf surfaces or skins, always play an important role in the survival of plants and animals. However, in contrast, the research of artificially fabricated biomimetic superhydrophobic surfaces still remains at an initial stage in laboratory. To date, the major challenge for the practical application of superhydrophobic surfaces is their durability, which hence arouse more attention. The improvement of surface durability is of great significance for the application of superhydrophobic materials in real world. According to the difference in the dimensions of superhydrophobic materials and the differences in the dimensions of superhydrophobic structure units, the superhydrophobic materials are divided into five categories, namely the two-dimensional (2D) superhydrophobic surface based on zero-dimensional (0D) particle; the three-dimensional (3D) superhydrophobic material based on zero-dimensional (0D) particle; the two-dimensional (2D) superhydrophobic surface based on one-dimensional (1D) fiber; the three-dimensional (3D) superhydrophobic material based on one-dimensional (1D) fiber and the three-dimensional (3D) superhydrophobic material based on three-dimensional (3D) bulk material. The preparation methods and the studies of surface durability of each category are introduced. According to the research progress of durable superhydrophobic materials in recent years, the mechanisms for improving the durability of superhydrophobic materials are studied and the guidance to advance the application of superhydrophobic materials in real world are offered.