On the 2H- to 3C-Type Transformation and Growth Mechanism of SiC Nanowires upon Carbothermal Reduction of Rice Straws.

SiC nanowires (NWs) and nanoparticles (NPs) fabricated by carbothermal reduction of rice straws with/without FeSi catalysts were characterized by transmission electron microscopy to study the catalyst-facilitated vapor-liquid-solid (VLS) growth against the oriented attachment of the crystals, which underwent 2H- to 3C-type transformation. The cotectic melt of the FeSi catalyst in the Fe-Si-C-O system turned out to promote the VLS growth to form straight and occasionally tapered NWs in contrast to the zigzag ones via the (hkl)-specific coalescence of the faceted NPs. The SiC NWs showed [0001]2H-directed growth more or less stacked with {111}3C interlayers following the optimum crystallographic relationship (0001)2H//{111̅}3C; [21̅1̅0]2H//⟨101⟩3C with zigzag {111}3C lateral steps and polysynthetic twins/faults near the (0001)2H/(111)3C interface. The FeSi-assisted VLS growth and twinning/stacking fault-coupled 2H to 3C phase change may be extended to novel green manufacturing and design of sustainable resources for other semiconductor NWs.

Magnetic and Magneto-Optical Oroperties of Iron Oxides Nanoparticles Synthesized under Atmospheric Pressure.

Magnetite nanoparticles were synthesized by a simple thermal decomposition process, involving only iron (III) nitrate nonahydrate as a precursor, and hexadecylamine as a solvent and stabilizer at reaction temperatures varied from 200 to 380 °C. The results of the structural analysis showed that the average crystallite size depends on the reaction temperature and increases from 4.8 to 13.3 nm. The behavior of the coercivity indicates that all synthesized samples are single domain; herewith, it was found that the critical size corresponding to the transition to the superparamagnetic state at room temperature is about 9 nm. The effect of the reaction temperature on changes in the saturation magnetization was studied. It was found that the size effect in the MCD spectra is observed for the IVCT transition and one ISCT transition, and the influence of the reaction temperature on the change in the MCD spectra was discussed.

Data on the identification of isoprene and Styrene triblock copolymers with difunctional t-BuLi initiator.

The data article refers to the paper "Synthesis of High-Vinyl Isoprene and Styrene Triblock Copolymers via Anionic Polymerization with Difunctional t-BuLi Initiator" [1]. Data presented here include the number average molecular weight (M n ), the weight average molecular weight (M w ), and polydispersity index (PDI) (M w /M n ) of the triblock copolymers poly(styrene)-b-poly(isoprene)-b-poly(styrene) (PS-b-PI-b-PS, SIS) and poly(isoprene)-b-poly(styrene)-b-poly(isoprene) (PI-b-PS-b-PI, ISI). M n of SIS and ISI were in the range of 208,000 to 274,000 (g/mol) and PDI of SIS and ISI are located at 1.18 to 1.2, respectively. The triblock copolymers were further identified with 2D HSQC NMR spectrum. Different vinyl content (1,2- and 3,4-addition units) of polyisoprene domains were characterized in the data.

Wearable Woven Triboelectric Nanogenerator Utilizing Electrospun PVDF Nanofibers for Mechanical Energy Harvesting.

Several wearable devices have already been commercialized and are likely to open up a new life pattern for consumers. However, the limited energy capacity and lifetime have made batteries the bottleneck in wearable technology. Thus, there have been growing efforts in the area of self-powered wearables that harvest ambient mechanical energy directly from surroundings. Herein, we demonstrate a woven triboelectric nanogenerator (WTENG) utilizing electrospun Polyvinylidene fluoride (PVDF) nanofibers and commercial nylon cloth to effectively harvest mechanical energy from human motion. The PVDF nanofibers were fabricated using a highly scalable multi-nozzle far-field centrifugal electrospinning protocol. We have also doped the PVDF nanofibers with small amounts of multi-walled carbon nanotubes (MWCNT) to improve their triboelectric performance by facilitating the growth of crystalline ß-phase with a high net dipole moment that results in enhanced surface charge density during contact electrification. The electrical output of the WTENG was characterized under a range of applied forces and frequencies. The WTENG can be triggered by various free-standing triboelectric layers and reaches a high output voltage and current of about 14 V and 0.7 µA, respectively, for the size dimensions 6 × 6 cm. To demonstrate the potential applications and feasibility for harvesting energy from human motion, we have integrated the WTENG into human clothing and as a floor mat (or potential energy generating shoe). The proposed triboelectric nanogenerator (TENG) shows promise for a range of power generation applications and self-powered wearable devices.

Electrochemical immunosensor utilizing electrodeposited Au nanocrystals and dielectrophoretically trapped PS/Ag/ab-HSA nanoprobes for detection of microalbuminuria at point of care.

In this study, we have fabricated a simple disposable electrochemical immunosensor for the point of care testing of microalbuminuria, a well-known clinical biomarker for the onset of chronic kidney disease. The immunosensor is fabricated by screen-printing carbon interdigitated microelectrodes on a flexible plastic substrate and utilizes electrochemical impedance spectroscopy to enable direct and label free immunosensing by analyzing interfacial changes on the electrode surface. To improve conductivity and biocompatibility of the screen-printed electrodes, we have modified it with gold nanoparticles, which are electrodeposited using linear sweep voltammetry. To enable efficient immobilization of HSA antibodies, we have developed novel PS/Ag/ab-HSA nanoprobes (polystyrene nanoparticle core with silver nanoshells covalently conjugated to HSA antibodies), and these nanoprobes are trapped on the electrode surface using dielectrophoresis. Each immunosensor has two sensing sites corresponding to test and control to improve specificity by performing differential analysis. Immunosensing results show that the normalized impedance response is linearly dependent on albumin concentration in the clinically relevant range with good repeatability. We have also developed a portable impedance readout module that can analyze the data obtained from the immunosensor and transmit it wirelessly for cloud computing. Consequently, the developed immunosensing platform can be extended to the detection of a range of immunoreactions and shows promise for point of diagnosis and public healthcare monitoring.

Preparing chelated copolymer membrane for fabrication of Ag dendrites.

A novel method to prepare Ag dendrites on the surface of polymer membranes, which was synthesized by using the soap-free emulsion copolymerization of n-butylacrylate (BA) and acrylonitrile (AN), as well as 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester (GMA-IDA) that was used as a chelating group, is presented in this study. The characteristics of polymer membranes were investigated by Fourier transform infrared (FT-IR) spectroscopy and elementary analysis (EA). The weight fraction of the chelating group (GMA-IDA) in the polymer was 4.2% as revealed by elemental analysis. The chelating group, -N(CH(2)COO(-)Na(+))(2) on the polymer was used to coordinate nickel(II) ions, whose chelating amount was estimated by an atomic absorption spectrophotometer (AA). The coordinated Ni(2+) ions were subsequently reduced to nickel nanoparticles, which functioned as templates for growing Ag dendrites from aqueous solution of Ag(+)/poly(vinyl pyrrolidone) (PVP) aqueous solution. The phase identification of the Ag dendrites was confirmed by X-ray diffraction (XRD). Scanning electronic microscopy (SEM) showed the averaged dimension of Ag dendrites was about 2-3 microm in length and ca. 100 nm in diameter. Moreover, the amount of Ag dendrites increased with the decreasing PVP concentration present in the aqueous solution. The energy dispersive X-ray spectrometer (EDX) reveals that the formation of the Ag dendrites was chiefly through the redox reaction of nickel nanoparticles and Ag(+) ions, namely galvanic reaction.

Synthesis of yttrium iron garnet using polymer-metal chelate precursor.

Two kinds of polymer-metal compounds, heterogeneous complexes (metal-chelating copolymer microspheres, MCP) and homogeneous complexes (water-soluble metal-chelating polymers, WSMCP), were synthesized to act as nucleation agents for YIG precursor preparation in this text. Both of the metal-chelating polymers have the same chelating group and high metal ion adsorption ability from the FTIR and ICP measurement. Furthermore, good YIG crystals can be obtained by treating the MCP precursor with a low calcination temperature at 600 degrees C from the XRD spectra and TEM micrograph. However, the YIG crystal obtained using a WSMCP precursor should be synthesized at a higher calcination temperature (>900 degrees C) due to the different components of the YIG precursor. In addition, the YIG crystal obtained by using the MCP precursor had nearly superparamagnetic behavior after VSM examination.

Polypropylene fibers modified by plasma treatment for preparation of Ag nanoparticles.

A novel method for preparing poly(propylene-graft-2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester)-silver fibers (PPG-IAg fibers) by plasma-induced grafting polymerization is presented in this study. The chelating groups, -N(CH2COO-)2 (GMA-IDA), on the surface of the PPG-I fibers are the coordination sites for chelating silver ions. At these sites, Ag nanoparticles were grown first by reduction with UV light with a wavelength of 366 nm, and second, through immersion in a 24% formaldehyde solution with pH values set variously at 2, 5, 8, and 11. The characteristics of the PPG-I fibers with differing durations of plasma treatment were monitored by using a Fourier transform infrared (FT-IR) spectroscope. Scanning electronic microscopy (SEM) and elemental analysis show that the percentage of GMA-IDA grafted onto PP fiber reaches a maximum when the plasma treatment time is 3 min. Plasma treatment time beyond a certain length of time results in an abundance of free radicals and causes considerable cross-linking on the fiber surface which thus decreases the extent of grafting. Moreover, the crystalline phase of Ag nanoparticles is identified by using X-ray diffraction (XRD). When the PPG-I fibers are reduced by the UV light method, SEM and TEM microscopes reveal that the size of the Ag nanoparticles on the fiber surface decreases significantly with the increase of pH values in aqueous solutions. Notably, in the reduction of formaldehyde solution, the particle size of Ag nanoparticles reaches a minimum at the lowest pH value. The TEM observations show that Ag nanoparticles are distributed both in the exterior and interior of the grafting layer. In addition, under high pH values the distribution of the Ag nanoparticles permeate more deeply in the GMA-IDA grafting layer due to the swelling effect of the GMA-IDA polymer.

Effect of chelating functional polymer on the size of CdS nanocluster formation.

Chelating poly(acrylates-co-2-methylacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester) microspheres of diameter 250-310 nm were prepared by the soap-free emulsion polymerization method for varying amounts of GMA-IDA. Then CdS/copolymer composite was generated by chemical deposition on the surface of the copolymer microspheres. By XRD analysis it is found that the chelated CdS nanoparticles are a pure cubic zinc blende structure. The CdS/copolymer composite is examined by UV-vis absorbance, photoluminescence, and TEM observation. Average CdS nanoparticle size calculated from Henglein's empirical curve is in the range of 3.0-8.0 nm and varies according to the GMA-IDA molar ratio during polymerization, pH value during chelation, and postchelation annealing temperature. Higher ratio of chelating group, pH value, and annealing temperature produce larger CdS nanoparticles. As GMA-IDA ratio increases, photoluminescence exhibits a red shift from 510 to 520 nm, photoluminescence increases, and bandwidth decreases. Photoluminescence of the CdS nanoparticle becomes negligible when diameter exceeds 5 nm.

Modification of polypropylene fibers by plasma and preparation of hybrid luminescent and rodlike CdS nanocrystals/polypropylene fibers.

A simple method for the preparation of hybrid luminescence and rodlike CdS nanoclusters/poly (propylene-grafted-(2-methylacrylic acid 3-(bis-carboxymethyl amino-2-hydroxy-propyl ester) (GMA-IDA fibers, by plasma induced method following chemical deposition method, is presented in this study. GMA-IDA chelating groups which are grafted onto the poly(propylene) fibers are the coordination sites for chelating Cd+2, on which nano-sized CdS nanocrystals grew. TEM observations demonstrate that the mean diameter of CdS nanocrystals inside the poly(PP-graft-GMA-IDA) fibers alters from 2 nm to 8 nm at various concentrations of S2- solution. Additionally, SEM presents that the CdS nanocrystals on the surface have rod-like structure. The UV-vis absorption spectra provide the information of the absorption edges, band-gaps, and average diameter of CdS nanocrystals, the results of which are coincidence with the TEM observations. Furthermore, the photoluminescence (PL) shows the maximum peaks are 495 nm, 571 nm, 657 nm, and 675 nm corresponding to the mean particle sizes 2.6 nm, 3.5 nm, 4.8 nm, and 7.7 nm, respectively, at an excitation wavelength of 366 nm.

Modification of multi-walled carbon nanotubes by plasma treatment and further use as templates for growth of CdS nanocrystals.

In this study, we present a novel method for preparing multi-walled carbon nanotubes (MWCNTs) grafted with a poly(2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester) (GMA-IDA)-cadmium sulfide complex (CNTs-G-ICdS complex) through plasma-induced grafting polymerization. The characteristics of the MWCNTs after being grafted with the GMA-IDA polymer were monitored by a Fourier transform infrared (FT-IR) spectroscope. Scanning electronic microscopy (SEM) shows that the amount of GMA-IDA grafted onto the MWCNTs increases with the concentration of GMA-IDA monomer. The complex resulting from GMA-IDA polymer grafting onto the MWCNTs, CNTs-G-I (15%), shows excellent dispersion properties in aqueous solution and has high Zeta potential values over a wide range of pH values, from 2 to 12. Moreover, Raman spectroscopy was used to confirm the successful chemical modification of MWCNTs through the plasma treatment. The chelating groups, -N(CH(2)COO(-))(2) in the GMA-IDA polymer grafted on the surface of the CNTs-G-I, are the coordination sites for chelating cadmium ions, and are further used as nano-templates for the growth of CdS nanocrystals (quantum dots). Moreover, TEM microscopy reveals that the size of the CdS nanocrystals on the CNT surfaces increases with increasing S(2-) concentration. In addition, high resolution x-ray photoelectron (XPS) spectroscopy was used to characterize the functional groups on the surface of the MWCNTs after chemical modification by the plasma treatment and grafting with GMA-IDA polymer.