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This work presents a low-temperature engineering strategy, from quantum dot (QD) synthesis to fabrication of a hybrid from a homogeneous dispersion to thermal annealing with elaborate use of a small organic molecule dopamine, for achieving a kind of ZnO QD-hybridized piezoelectric polymer film directly integrated into a flexible electrode and a plastic substrate. This strategy is the key for non-transfer assembly of flexible piezoelectric nanogenerators (FPENGs) with both mechanical robustness and high electrical performance via direct lamination. The rational addition of dopamine plays multiple roles of (1) significantly decreasing the size of ZnO particles to a QD level (3.77 nm), (2) formation of a stable and homogeneous dispersion of a ZnO QDs/piezoelectric polyvinylidene fluoride

Unconventional contact electrification between viscoelastic polymer adhesives and patterned silicone elastomers was developed for high-performance mechanical energy harvesters with unique frequency- and force-insensitive output characteristics.

Through full flexible realization of a new energy harvesting mode using only common fiber materials as active components by adopting a computerized knitting programme strategy, herein we developed a new kind of all-textile energy harvesters (A-TEHs) with a three-dimensional fabric structural integrity that can harvest and convert mechanical energy to electricity directly. The electric performance of obtained A-TEHs working at a single-electrode mode was extraordinary, which can generate a maximum power density of 1768.2 mW m−2 by 1200 N at a matched resistance load of 50 MΩ, and directly light up over 320 LEDs instantaneously by a single impact with an effective area of only 56.7 cm2. When A-TEH was used to charge a 200 µF commercial capacitor storage device with a bridge rectifier, its charging capacity increased with the triggering force, ranging from 6.7 mV s−1 at 100 N to 11.3 mV s−1 at 1400 N. Benefiting from the full structural integrity of fiber materials, A-TEHs, for the first time, truly realized the excellent textile properties that all wearable electronics try to achieve, including safety, lightweight, comfort, breathability, washability, and unique advantage of tailorability, leading to a kind of truly wearable energy harvesters with versatile product designability.

The conventional use of textiles as substrates for the incorporation of brick materials (i.e., polymers and nanomaterials) is ubiquitously developed with primary purposes for introducing desired technical/functional performance rather than maintaining the aesthetic/decorative characteristics and inherent advantages (i.e., flexibility and permeability) of textiles. Such kinds of modified textiles with typical solid coating layers, however, are becoming more and more unsuitable for some emerging applications, such as smart wearable devices. Herein, we presented a brand-new kind of modified textiles with brick materials formed contouring to the nonplanar fiber surfaces of a fabric substrate as a three-dimensional (3D) conformal layer of porous microstructures by a unique breath figure self-assembling strategy of employing water microdroplet arrays as soft dynamic templates that can be controlled, formed, and removed spontaneously. In this paper, the main influential factors such as solution concentration, relative humidity, temperature, brick materials, and fabric substrates were studied systematically to control and adjust the formation of 3D conformal porous microstructures (3CPMs). The obtained 3D conformal porous microstructured textiles (3CPMTs) hierarchically combining the inherent texture features of the porous network of textiles and honeycomb porous microstructures templated from water microdroplet arrays not only possess new functions of introduced brick materials (such as triboelectric performance and wettability) and maintain the excellent inherent advantages (such as flexibility, air permeability, water vapor permeability, and unique texture features) of fabrics but also enhance the tensile strength and thermal insulation performance of substrates. Taking advantage of the introduced functions, they can be either used for conventional applications (i.e., oil/water separation) with enhanced performance or explored for new applications (i.e., self-powered sensors with textile breathability and comfort) with truly wearable potential. We believe this efficient, robust, and versatile strategy opens up numerous possibilities for designing and developing a broad range of advanced multifunctional textiles upon end uses.

Fibers have been widely used for wearable textiles and fiber-reinforced composites owing to their unique structures and performances. However, design and fabrication of 1D advanced fiber materials with diversified surface microstructures and desired functionalities is still a considerable challenge. In this study, we present a novel one-dimensional confined breath figure (1D-cBF) approach for efficient preparation of a brand-new kind of 1D continuous fibers surface-engineered with conformal honeycomb porous microstructures (F@HPMs) and a novel kind of Hybrid F@HPMs (HF@HPMs) with functional nanomaterials incorporated in porous microstructures. The obtained F@HPMs demonstrated controllable surface microstructural morphologies by adjusting the experimental variables, and the main influential factors including solvents, concentrations, polymer bricks, and substrates in the 1D-cBF process were systematically studied. Moreover, various functional nanocomponents could be incorporated for developing HF@HPMs for customized functionalities. As a demonstration, TiO2/HF@HPMs that incorporate with TiO2 nanoparticles were fabricated for enhanced photodegradation of organic pollutants.

A fiber material is composed of a group of flexible fibers that are assembled in a certain dimensionality. With its good flexibility, high porosity, and large surface area, it demonstrates a great potential in the development of flexible and wearable electronics. In this work, a kind of nickel/active material-coated flexible fiber (NMF) electrodes, such as Ni/MnO2/reduced graphene oxide (rGO) NMF electrodes, Ni/carbon nanotube (CNT) NMF electrodes, and Ni/G NMF electrodes, is developed by a new general method. In contrast with previous approaches, it is for the first time that porous and rich hydrophilic structures of fiber materials have been used as the substrate to fully absorb active materials from their suspension or slurry and then to deposit a Ni layer on active material-coated fiber materials. The proposed processes of active material dip-coating and then Ni electroless plating not only greatly enhance the electrical conductivity and functional performance of fiber materials but also can be applie...

Flexible piezoelectric nanogenerators (FPENGs) have attracted a great attention owing to their promising applications in harvesting mechanical energy and driving portable devices. To develop high-performance FPENGs, the significant relationship among material, structure and performance inspired us a rational design of FPENGs from Pdop-BaTiO3@P(VDF-TrFE) nanocomposite fiber mats with a hierarchically architected microstructure. In contrast with previous approaches, the polydopamine (Pdop) modified barium titanate (BaTiO3, BT) nanoparticles have been anchored onto the surface of electrospun poly (vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) fibers to fabricate hierarchical micro-structured membrane in this study, which not only effectively avoids the agglomeration of nanofillers but also enhances the density of interfaces in the nanocomposites. As a result, the as-fabricated FPENGs show a significantly enhanced output of 6 V and 1.5 μA as compared to the PENG with only P(VDF-TrFE) membrane (1.25 V and 0.6 μA). Furthermore, output voltage of the new FPENGs is 40%–68% higher than that of composite membranes with nanoparticles at the interior of nanofibers. The improved output of the PENG is attributed to the high density of interfaces in the hierarchical microstructure and the corresponding enhancement of dielectric response. Then, electric performance of FPENGs was investigated in terms of force, frequency and load resistance. Finally, the FPENG was employed to efficiently detect human body movements as self-powered sensors. The hierarchical nanocomposite membrane designed in this study provides an effective approach for developing mechanical energy harvesters, wearable sensor network and self-powered devices.

Three-dimensionally conformal porous microstructured fabrics (3CPMFs) are a new kind of modified fabrics with three-dimensionally conformal porous microstructures of introduced materials recently developed for wearable technology. They can effectively introduce customized functional performance based on the choice of brick materials, while at the same time maintain the excellent inherent properties of textiles. In this paper, based on the introduction of polystyrene with low thermal conductivity at only 8 &times, 10&minus, 4 g cm&minus, 2, we developed a kind of polyester fabric-based 3CPMF with enhanced thermal insulation, while maintaining its unique fabric texture, flexibility, moisture permeability, and light weight. It was demonstrated to be a good textile material for the fabrication of wearable electrothermal textile (ET) devices with enhanced thermal management. Compared to pristine fabric-based ET devices, this kind of 3CPMF-based ET devices can obtain higher temperatures under the same input power to provide thermal comfort for human beings, while saving more electric power to achieve the same thermal equilibrium temperature. We believe that, based on the choice of different functional materials and textiles, a wide range of 3CPMFs with customized functionalities and properties can be designed and developed for the realization of a brand-new class of truly wearable devices with desired functional performance and daily garment-like safety and comfort.

An aramid-assisted acid spinning strategy was developed for rapid fabrication of continuous macroscopic multi-walled carbon nanotube (MWCNT) fibers by dispersing MWCNTs and Kevlar into most widely used concentrated sulfuric acid (>95%). The resultant fibers comprising over 85 wt% MWCNTs had a high strain rate of approximately 11.90%, and held enough mechanical strength for further twisting. The twisted three-ply yarns maintained the high-elastic character of single fibers (up to 13.18%), meanwhile possessed a high tensile load capacity of 360.24 mN, and a good conductivity of 154.43 S · cm−1, which were believed to have promising applications for wearable electronics, energy conversion and storage devices in harsh environments.

A robust asphalt-assisted breath figure templating approach has been developed for general fabrication of ordered porous polymer films and functional hybrid films with hierarchical microstructures. The incorporation of desired non-polymeric components, such as titanium dioxide nanoparticles and silver nanowires, shows little influence on the regularity of the pore arrays.

Breath figures (BFs) are a kind of water droplet arrays that can be formed by condensing aqueous vapor onto a cold surface, such as dewy phenomenon on a spider web. This study developed a BF-inspired approach for direct introduction of desired materials onto the textile surfaces with three-dimensionally conformal porous microstructures by the evaporation of solution-coated fabric under high humidity environment, which brings a brand-new kind of modified textiles, three-dimensionally conformal porous microstructured fabrics (CPMFs). Such kind of CPMFs can possess customized multifunctional properties of introduced materials, and meanwhile maintain the inherent properties and unique texture features of fabrics. This nature-inspired BF approach is robust and versatile for customized preparation of CPMFs based on different fabrics with different common polymers. Moreover, it is also feasible for one-step functionalization of CPMFs by the incorporation of nanoparticles (such as titanium dioxide nanoparticles, TiO2 NPs) into the porous microstructures during the BF process. Comparing to the sample modified without porous microstructures, the resultant TiO2 NPs-incorporated CPMFs show an obviously enhanced performance on photocatalytic degradation of pollutants under the same ultraviolet irradiation conditions.

A triboelectric nanogenerator (TENG) is an innovative kind of energy harvester recently developed on the basis of organic materials for converting mechanical energy into electricity through the combined use of the triboelectric effect and electrostatic induction. Polymeric materials and their microstructures play key roles in the generation, accumulation, and retainment of triboelectric charges, which decisively determines the final electric performance of TENGs. Herein we report a simple and efficient breath figure (BF) micromolding approach to rapidly regulate the surface microstructures of polymeric films for the assembly of TENGs. Honeycomb porous films with adjustable pore size and dimensional architectures were first prepared by the BF technique through simply adjusting the concentration of the polymer solution. They were then used as negative molds for straightforward synthesis of polydimethylsiloxane (PDMS) films with different microlens arrays (MLAs) and lens sizes, which were further assembled for TENGs to investigate the influence of film microstructures. All MLA-based TENGs were found to have an obviously enhanced electric performance in comparison with a flat-PDMS-film-based TENG. Specifically, up to 3 times improvement in the electric performance can be achieved by the MLA-based TENG with optimal surface microstructures over flat-PDMS-film-based TENG under the same triggering conditions. A MLA-based TENG was further successfully used to harvest the waste mechanical energy generated by different human body motions, including finger tapping, hand clapping, and walking with a frequency ranging from 0.5 to 5.5 Hz.

A silicon-containing graft copolymer, poly(dimethylsiloxane)-graft-polyacrylates, was explored as single-source precursor for the preparation of silicon oxycarbide (SiOC) with honeycomb microstructures by a novel reliable approach composed of breath figure (BF) process, plasma modification and pyrolysis. Multilayer ordered porous films prepared by a static BF process were treated by oxygen plasma at room temperature, and used as templates for in situ formation of honeycomb microstructured SiOC sheets by further pyrolysis. Plasma modification is believed to play a key role in templating the formation of patterned SiOC sheets because no special features were found when pyrolysing the unmodified films. The formed sheets possess a nanometer-thickness top layer with an average pore diameter of 1.893 µm.

The microstructure of asphalt materials on photocatalytic performance was studied in this work. Firstly, asphalt composite coatings with highly ordered honeycomb microstructures were fabricated by a bottom-up approach through adjusting the solution concentration and the content of polystyrene (PS) additive. Further incorporation of titanium dioxide (TiO2) nanoparticles endows the porous coatings with photocatalytic functionality. SEM images demonstrate that TiO2nanoparticles disperse and decorate on the pore walls of coating. In comparison to the compact coatings prepared by traditional method, the obtained honeycomb microstructured asphalt/PS/TiO2coatings possess an enhanced and sustainable efficiency of removing NOx. Specifically, when introducing porous microstructures to the coating, the NOxreduction efficiency is 16% higher than that of traditional compact sample and shows no attenuation in continuous use.

The intense interest surrounding asymmetrical microparticles originates from their unique anisotropic properties and promising applications. In this work, direct self-assembly of polymeric microspherical caps without the assistance of any additives has been achieved by using low-surface-tension methanol (MeOH) and high-surface-tension water as binary breath figures (BFs). With the evaporation of polystyrene (PS) solution containing low-boiling-point solvent in the binary vapors, the formed MeOH BFs could quickly diffuse into solution, while water BFs tended to remain at the solution surface. This led to the formation of a gradient nonsolvent layer at the vapor/solution interface, which induced the formation of nuclei and guided further asymmetrical growth of polymer particles. After the spontaneous removal of MeOH, water and residual solvent by evaporation, polymeric microspherical caps were left on the substrate. Through controlling the proportion of water introduced by adjusting the ratios of MeOH and water, polymeric microspherical caps with a range of controllable shapes (divided at different positions of a sphere) were successfully obtained. The formation mechanism was explained based on the difference of vapor pressure, surface tension and miscibility between the employed solvents and nonsolvents. A solvent possessing a high vapor pressure, low surface tension and good miscibility with MeOH contributed to the formation of microspherical caps. This flexible, green and straightforward technique is a nondestructive strategy, and avoids complicated work on design, preparation and removal of hard templates and additives.

Here, we present the static breath figure process for constructing 3-dimensionally conformal microporous films on nonplanar substrates, with a commercially available triblock polymer, polystyrene-b-polyisoprene-b-polystyrene. The polymer can cover the surface of nonplanar substrates with ordered porous morphology despite the sharp corners and irregular shapes, which was ascribed to the fluid-like character of the matrix. In the subsequent vulcanization, the micro-patterned polymer films were effectively crosslinked and became self-supported even after removing the sacrificial templates. The 3D structures became resistant to a wide range of organic solvents and thermally stable up to 350 °C, an increase of more than 300 K as compared to the un-crosslinked films. The surface features on the 3D structures along the direction of the descending solvent level were investigated in detail by scanning electron microscopy. Furthermore, the versatility of this patterning method was also demonstrated by forming hierarchical micro-structures on bas-relief Si substrates with different patterns. Particularly, hydroxy groups were introduced into another commercially available triblock polymer, polystyrene-b-polybutadiene-b-polystyrene by hydroboration. The functionalized 3D micro-patterns feasible for site-directed grafting were created by the hydroxyl-containing polymers.

Rapid advances in functional electronics bring tremendous demands on innovation toward effective designs of device structures. Yarn supercapacitors (SCs) show advantages of flexibility, knittability, and small size, and can be integrated into various electronic devices with low cost and high efficiency for energy storage. In this work, functionalized stainless steel yarns are developed to support active materials of positive and negative electrodes, which not only enhance capacitance of both electrodes but can also be designed into stretchable configurations. The as-made asymmetric yarn SCs show a high energy density of 0.0487 mWh cm-2 (10.19 mWh cm-3 ) at a power density of 0.553 mW cm-2 (129.1 mW cm-3 ) and a specific capacitance of 127.2 mF cm-2 under an operating voltage window of 1.7 V. The fabricated SC is then made into a stretchable configuration by a prestraining-then-releasing approach using polydimethylsiloxane (PDMS) tube, and its electrochemical performance can be well maintained when stretching up to a high strain of 100%. Moreover, the stretchable cable-type SCs are stably workable under water-immersed condition. The method opens up new ways for fabricating flexible, stretchable, and waterproof devices.

Patterning is of paramount importance in many areas of modern science and technology. As a valuable part in miniaturized devices, large-scale aligned CNTs with serial port configuration is highly desirable. Here, we reported that the synthesis of a pair of patterned carbon nanotubes with the shape of serial port by CVD starting from different breath figure templates, cross-linked polymer matrix and ferrous inorganic micropatterns. The growth mechanism of the isolated CNT bundles is attributed to the selectively interfacial aggregation of the ferrocene to the walls of the cavities, a so-called Pickering-emulsion effect, whereas the honeycomblike skeleton of the dense CNT arrays develop from the catalytically functionalized hexagonal edges. This synthesis strategy exemplifies a new possibility for making use of CNTs to fabricate functional carbons with unique geometry or specific properties in a controllable way. We expect that the methodology can be also applied onto the fabrication of patterned graphene.

Wireless Sensor Network (WSN) is the hot research topic. In order to adapt to the future development direction of WSN, this paper presented a movement control strategy based on virtual repulsion in Multi-tier Mobile Sensor Network. The strategy first used a hierarchical node aggregation algorithm to divide all sensor nodes into many communication clusters in the monitoring area. It combines virtual repulsive force to distribute nodes uniformity in every cluster. Finally, using aggregation algorithm again based on the nodes uniform distribution to design fusion nodes' optimal movement route for data collection. The simulation results show that the strategy can ensure the efficiency of network data collection, reduce data loss rate, and nodes power consumption.

Self-localization of sensor nodes is one of the important technologies in wireless sensor networks. APIT is a range-free localization algorithm; it has the advantages of high localization accuracy and low communication overhead. However, the localization coverage of APIT is low, and when the proportion of anchor nodes is low, APIT is prone to OutToIn and InToOut error. To solve the above problems, this paper proposed a new point-in-triangulation test method based on cosine theorem according to APIT's basic idea to prevent OutToIn and InToOut error, and added RSSI model to locate the unknown nodes which are judged outside the triangles through trilateral measurement method to improve the localization coverage. Simulation results shows that compared with APIT algorithm, the new algorithm has higher localization accuracy and coverage.

In Qiao's previous report, only star polymers with T(g) (glass transition temperature) below 48°C were found forming homogeneous honeycomb coatings on the nonplanar substrates. The polymers with high T(g) are believed not able to duplicate nonplanar substrate due to their brittleness. This article presents a comprehensive study on the construction of macroporous polymeric films on various nonplanar substrates with static breath figure (BF) technique, using linear polymers with high T(g). Two kinds of linear polymers with high T(g), polystyrene-b-poly(acrylic acid) and polystyrene without polar end groups, are employed to prepare 3-dimensional macroporous films on different nonplanar substrates. Scanning electronic microscopy views on the side wall in addition to views in-plane prove that polymer films with BF array perfectly replicated the surface features of these substrates. The formation processes of macropores on these substrates are analyzed in detail, and it demonstrates that neither molecular topography nor T(g) of polymers is the critical factor contouring nonplanar substrate. A new hypothesis involving polymer plasticization and conformation during the solvent evaporation is formulated.

Multi-level carbon nanotube (CNT) arrays with adjustable patterns were prepared by a combination of the breath figure (BF) process and chemical vapor deposition. Polystyrene-b-poly(acrylic acid)/ferrocene was dissolved in carbon disulfide and cast onto a Si substrate covered with a transmission electron microscope grid in saturated relative humidity. A two-level microporous hybrid film with a block copolymer skeleton formed on the substrate after evaporation of the organic solvent and water. One level of ordered surface features originates from the contour of the hard templates; while the other level originates from the condensation of water droplets (BF arrays). Ultraviolet irradiation effectively cross-linked the polymer matrix and endowed the hybrid film with improved thermal stability. In the subsequent pyrolysis, the incorporated ferrocene in the hybrid film was oxidized and turned the polymer skeleton into the ferrous inorganic micropatterns. Either the cross-linked hybrid film or the ferrous inorganic micropatterns could act as a template to grow the multi-level CNT patterns, e.g. isolated and honeycomb-structured CNT bundle arrays perpendicular to the substrate.

Here, we present the preparation of thermally stable and solvent resistant micro-patterned polymeric films via static breath-figure process and sequent vulcanization, with a commercially available triblock polymer, polystyrene-b-polyisoprene-b-polystyrene (SIS). The vulcanized honeycomb structured SIS films became self-supported and resistant to a wide range of organic solvents and thermally stable up to 350°C for 2h, an increase of more than 300K as compared to the uncross-linked films. This superior robustness could be attributed to the high degree of polyisoprene cross-linking. The versatility of the methodology was demonstrated by applying to another commercially available triblock polymer, polystyrene-b-polybutadiene-b-polystyrene (SBS). Particularly, hydroxy groups were introduced into SBS by hydroboration. The functionalized two-dimensional micro-patterns feasible for site-directed grafting were created by the hydroxyl-containing polymers. In addition, the fixed microporous structures could be replicated to fabricate textured positive PDMS stamps. This simple technique offers new prospects in the field of micro-patterns, soft lithography and templates.

We describe a facile method to micropattern solid substrates: breath figure lithography (BFL). A honeycomb structured gold mask was prepared by sputter-coating a micro-porous polymer film with BF arrays, and then inductively coupled plasma reactive ion etching (ICP-RIE) transferred the patterns onto silicon wafer. The large etching rate selectivity between golden mask and substrate plays an important role in the effective transfer of the patterns. The versatility of the method was demonstrated by forming micropatterns on various solid substrates with adjustable sizes. Furthermore, the micropatterns on solid substrate could be replicated by PDMS stamp.

Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO(2)-expanded liquid (CXL), CO(2)-methanol. The phase behavior of the CO(2)-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO(2), forming homogeneous CXL under the experimental conditions. When treated with the CO(2)-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a temperature range of 45-60 °C. The formation mechanism of the network, involving plasticization of PS and selective swelling of P4VP, was proposed. Because the diblock copolymer diffusion process is controlled by the activated hopping of individual block copolymer chains with the thermodynamic barrier for moving PVP segments from one to another, the formation of the network structures is achieved in a short time scale and shows "thermodynamically restricted" character. Furthermore, the resulting polymer networks were employed as templates, for the preparation of polypyrrole networks, by an electrochemical polymerization process. The prepared porous polypyrrole film was used to fabricate a chemoresistor-type gas sensor which showed high sensitivity towards ammonia.

Here, we show a facile and versatile method preparing highly ordered ceramic microstructures on solid substrates by pyrolyzing UV cross-linked copolymer films to circumvent the expensive lithographic technique. The employed block copolymer, poly(dimethylsiloxane)-block-polystyrene (PDMS-b-PS), in this study was synthesized by controlling radical polymerization. The highly ordered microporous polymer films were formed using a static breath figure process. After 4 h UV irradiation, the PS composition was effectively cross-linked. The cross-linked microporous polymer matrix served as a structure-directing agent in the following pyrolysis process, in which the PDMS composition was converted into silica to form honeycomb structured micropatterns on the substrate. The chemical components of the ceramic microstructures were adjusted by simply mixing different functional precursors. Moreover, the ceramic microstructures on substrate could be replicated to prepare textured PDMS stamps. This simple technique offers new prospects in the fields of micropatterns, soft lithography and templates.