Poly(3-hexylthiophene)/hexamine modified ZnO hybrid nanocomposite: structural,optical, thermal and electrical transport studies

This paper reports the synthesis of poly(3-hexylthiophene) (P3HT)/HA@ZnO nanocomposite by in situ polymerization and demonstrates their thermal, morphological and optoelectronic properties. Zinc oxide (ZnO) nanoparticles were prepared by the simple approach of co- precipitation method using zinc acetate dihydrate as precursor modified by hexamine (HA) acting as a capping agent. Structural and photo physical studies shows that conjugated polymer chains intimately contact with the inorganic semiconductor. ZnO has wurtzite structure with average crystallite size of 40 nm. The emission spectra indicate that modified ZnO nanoparticles results in more efficient photo induced charge transfer than that of the simple nanocomposite of P3HT/ZnO. The morphological studies revealed that the transformation of granular morphology of P3HT to the clusters in P3HT/HA@ZnO hybrid nanocomposites. Cyclic voltammeter elucidates the electrochemical behavior and the HOMO–LUMO energy levels of the nanocomposites. The results indicate that the P3HT/HA@ZnO nanocomposite has energy gap of 0.72 eV, indicating this composite has potential for the fabricating hybrid organic–inorganic solid state solar cells. A solar to electric energy conversion efficiency of 0.1238 % was attained with the system.     

Polyaniline nanofiber/gold nanoparticle nonvolatile memory

A nonvolatile plastic digital memory device based on nanofibers of the conjugated polymer polyaniline decorated with gold nanoparticles is reported. The device has a simple structure consisting of the plastic composite film sandwiched between two electrodes. An external bias is used to program the ON and OFF states of the device that are separated by a 3-orders-of-magnitude difference in conductivity. ON-OFF switching times of less than 25 ns are observed by electrical pulse measurements. The devices possess prolonged retention times of several days after they have been programmed. Write-read-erase cycles are also demonstrated. The switching mechanism is attributed to an electric-field-induced charge transfer from the polyaniline nanofibers to the gold nanoparticles. The active polymer layer is created by growing nanometer size gold particles within 30-nm-diameter polyaniline nanofibers using a redox reaction with chloroauric acid. This device combines two exciting research areas--nanoparticles and conducting polymers--to form a novel materials system with unique functionality.     

Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors.     

Enhanced performance of Au/P3HT/ (bilayer dielectrics)/Si thin-film-transistor having gold nanoparticles chemically bonded to P3HT

The charge transport enhancement of using poly(3-hexylthiophene) covalently bonded with gold nanoparticles as an active layer in a bottom-gate/top contact, Au/(P3HT)/(bilayer dielectric)/Si OTFT device has been studied. P3HT was synthesized via the modified Grignard metathesis method and functionalized to have a thiol terminal (P3HT(SH)). Gold nanoparticles (AuNPs) with sizes ranging from 2 to 10 nm were then formed via a reduction of HAuCl4 in the presence of P3HT(SH). Compared to the pristine P3HT, the AuNPs-containing P3HT composite materials have a higher energy level of HOMO and a smaller electrochemical bandgap E(g)chem. The smaller bandgap enhances the charge carrier mobility and the higher HOMO energy level indicates a reduced barrier and an increased injection rate for charge carrier at the source contact. Furthermore, the threshold voltage V(T) of AuNPs-containing P3HT samples remain nearly unchanged and their saturation current I(D) and the field-effect mobility are higher. An OTFT device fabricated with a composite sample containing 1.30% AuNPs has a carrier mobility and saturation current nearly two time higher than pristine P3HT.     

Layered nanocomposites from gold nanoparticles for neural prosthetic devices

Treatments of neurological diseases, diagnostics of brain malfunctions, and the realization of brain-computer interfaces require ultrasmall electrodes that are "invisible" to resident immune cells. Functional electrodes smaller than 50 μm are impossible to produce with traditional materials due to high interfacial impedance at the characteristic frequency of neural activity and insufficient charge storage capacity. The problem can be resolved by using gold nanoparticle nanocomposites. Careful comparison indicates that layer-by-layer assembled films from Au NPs provide more than 3-fold improvement in interfacial impedance and 1 order of magnitude increase in charge storage capacity. Prototypes of microelectrodes could be made using traditional photolithography. Integration of unique nanocomposite materials with microfabrication techniques opens the door for practical realization of the ultrasmall implantable electrodes. Further improvement of electrical properties is expected when using special shapes of gold nanoparticles.     

静电纺丝法制备金纳米粒子/PVP复合纳米纤维

采用水合肼还原一定浓度氯金酸溶液的方法,在聚乙烯吡咯烷酮(PVP)作保护剂的乙醇/水溶液中,成功制备出粒度较小,且高度分散的金溶胶,紫外吸收光谱证实了溶液中金纳米粒子的存在.采用静电纺丝技术制备了AuNs/PVP复合纳米纤维.采用扫描电镜(SEM)和X射线衍射(XRD)等分析手段对纤维的表面形貌等进行了表征.由扫描电镜...     

Toward transparent nanocomposites based on polystyrene matrix and PMMA-grafted CeO2 nanoparticles

The association of transparent polymer and nanosized pigment particles offers attractive optical materials for various potential and existing applications. However, the particles embedded into polymers scatter light due to refractive index (RI) mismatch and reduce transparency of the resulting composite material. In this study, optical composites based on polystyrene (PS) matrix and poly(methyl methacrylate) (PMMA)-grafted CeO(2) hybrid particles were prepared. CeO(2) nanoparticles with an average diameter of 18 ± 8 nm were precipitated by treating Ce(NO(3))·6H(2)O with urea in the presence of a polymerizable surfactant, 3-methacyloxypropyltrimethoxy silane. PMMA chains were grafted on the surface of the nanoparticles upon free radical in situ solution polymerization. While blending of unmodified CeO(2) particles with PS resulted in opaque films, the transparency of the composite films was remarkably enhanced when prepared by PMMA-grafted CeO(2) hybrid particles, particularly those having a PMMA thickness of 9 nm. The improvement in transparency is presumably due to the reduction in RI mismatch between CeO(2) particles and the PS matrix when using PMMA chains at the interface.     

Furan-Based Bionanocomposites Reinforced with a Hybrid System of Carbon Nanofillers

Bionanocomposites based on poly(trimethylene 2,5-furandicarboxylate)-block-poly(tetramethylene oxide) (PTF-b-F-PTMO) with various contents of carbon nanofibers, graphene nanoplatelets and a hybrid system of these nanoparticles are synthesized via in situ polymerization. The dispersion of nanoparticles in the nanocomposites is determined using a scanning electron microscope and optical microscopy images. The thermal properties are studied employing differential scanning calorimetry, dynamic mechanical thermal analysis, and thermogravimetric analysis. The melt viscosity of the synthesized materials is determined using rheological measurements. Mechanical properties, along with the thermal and electrical conductivity, are also analyzed. The synthesized polymer nanocomposites are processed using injection molding and they display mechanical properties of elastomers during mechanical testing, which indicates that the obtained materials are, in fact, thermoplastic elastomers (TPE). Compared to a neat matrix (PTF-b-F-PTMO 50/50), the incorporation of nanoparticles causes an increase in the value of the degree of crystallinity and the value of the tensile modulus values (E) of the nanocomposites. Such reinforced bionanocomposites are especially interesting from an applicative point of view. They can be used as components of fuel systems, bumpers, or cupholders.     

Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O₂ gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites.     

Preparation,solubility, and electrorheological properties of carbon nanotubes/poly(methyl methacrylate) nanocomposites by in situ functionalization

Poly(methyl methacrylate) (PMMA) nanobeads-decorated multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) nanocomposites were prepared using two processing steps. Initially, spherical PMMA nanoparticles were synthesized using an emulsion polymerization method. Afterward, the PMMA nanobeads were decorated to MWNTs and SWNTs using benzoyl peroxide as an initiator in water during a high temperature refluxing process. The results confirmed the linkage of the nanotubes to the surrounding PMMA nanobeads via a covalent bond. The resultant nanocomposites showed high solubility in chloroform without flocculation after 24 h. In addition, the nanotubes/PMMA nanocomposites were characterized by electrical resistance measurements to analyze their electrical conductivity and examined as electrorheological (ER) materials when dispersed in silicone oil.     

Electrospun light-emitting nanofibers

We have electrospun light-emitting nanofibers from ruthenium(II) tris(bipyridine)/polyethylene oxide mixtures. The electroluminescent fibers were deposited on gold interdigitated electrodes and lit in a nitrogen atmosphere. The fibers showed light emission at low operating voltages (3-4 V), with turn-on voltages approaching the band gap limit of the organic semiconductor. Because of the fiber size, emission from electrospun light-emitting nanofibers is confined to nanoscale dimensions, an attractive feature for sensing applications and lab-on-a-chip integration where highly localized excitation of molecules is required.     

Synthesis of core-shell Au@polypyrrole nanocomposite using a dendrimer-template approach

Conducting polymeric nanostructures have been reported recently, which were produced from polypyrrole (PPy), including hollow nanocapsules, nanofibers, nanoporous membranes, nanowires, and nanofilms. In most cases, new synthetic routes were used aimed at controlling specific properties of these conducting nanostructures at the molecular level. In this communication we present a new chemical route to synthesize polypyrrole-based nanocomposites, in which polyamidoamine (PAMAM) dendrimers encapsulating Au nanoparticles are used as template. The two-step synthesis comprises the reduction of Au nanoparticles inside PAMAM molecules followed by PPy polymerization around the PAMAM-Au nanoparticles. The structure of the core-shell PAMAM-gold@polypyrrole nanospheres comprises a 40 nm PPy shell enclosing a core of 3 nm gold nanoparticles, as revealed by Transmission Electronic Microscopy (TEM). This new, environmentally-friendly approach may be suitable to produce hybrid nanomaterials for applications in catalysis, batteries, sensors, and micro/nanoelectronic devices.     

Investigation of structural, optical, and electrical properties of regioregular poly(3-hexylthiophene)/fullerene blend nanocomposites for organic solar cells

We investigated the influence of thermal annealing on the structural and optical properties of two variations of organic nanocomposite materials; 1) poly [3-hexylthiophene] and [6,6]-phenyl C₆₁ butyric acid methyl ester ( P3HT:PC₆₁BM), and 2) poly [3-hexylthiophene] and [6,6]-phenyl C₇₁ butyric acid methyl ester) (P3HT:PC₇₁BM). The evolution of surface roughness and morphology was investigated using atomic force microscopy while device electrical properties were investigated by measuring current-voltage (I-V) characteristics. Upon thermal treatment, results show that P3HT:PC₇₁BM nanocomposites produce a more homogeneous mixture of finer grain size than P3HT:PC₆₁BM. Furthermore, stronger optical absorption in the visible region is observed in P3HT:PC₇₁BM compared to P3HT:PC₆₁BM. Since optical absorption is closely related to film crystallinity, it is inferred that P3HT:PC₇₁BM composites undergo more extensive crystallization upon annealing. Photoluminescence spectra of both P3HT:PC₆₁BM and P3HT:PC₇₁BM nanocomposites (dissolved in chlorobenzene) show that each has excellent quenching effects. I-V characteristic curves show that P3HT:PC₇₁BM registers higher current density under AM 1.5 illumination than does P3HT:PC₆₁BM. For the devices described in this paper having active areas of approximately 12 mm², efficiency is approximately 33% better for C₇₁-based solar cells than that observed for devices made using C₆₁ fullerene.     

Quantum dot sensitized solar cell based on poly (3-hexyl thiophene)/CdSe nanocomposites

The optoelectronic properties of P3HT–CdSe nanocomposites prepared by insitu chemical oxidative polymerization were studied. CdSe QDs were synthesized by hot injection method using tri octyl phosphine oxide (TOPO) as capping ligand whereas the P3HT polymer was prepared by chemical oxidative polymerization. FTIR studies confirmed the regioregularity of the P3HT and revealed the chemical interaction of P3HT and CdSe in nanocomposite. Absorption studies showed blue shift for the nanocomposites as compare to pristine P3HT, the electron transfer from conducting polymer to the CdSe was detected by the measurements of quenching of photoluminescence from conducting polymer after the addition of semiconductor nano crystals which confirmed that an optimum amount of nanoparticles provide networking in hybrid composites. The optimal result for device prepared by P3HT–CdSe nanocomposites was open circuit voltage (V_oc) 0.5, short circuit current density (J_sc) 0.66, Fill factor (FF) 0.6855 and efficiency (η) 0.22%.     

静电纺丝法制备PAN/Fe3O4磁性纳米纤维

采用化学共沉淀法制备纳米四氧化三铁,选用曲拉通X-100为分散剂,利用静电纺丝法制备PAN/Fe3O4磁性纳米复合材料。X射线衍射仪(XRD)验证了四氧化三铁在复合纳米纤维中的存在。同时使用扫描电镜(SEM)和透射电镜(TEM)对复合纳米纤维的微观形貌和Fe3O4在纤维中的分布进行了观察,利用热重(TGA)对纳米复合材料的热稳定性进行分析;通过磁性实验分析了纳米复合材料的磁性性能。结果表明,所制备PAN/Fe3O4磁性纳米纤维成型良好,且Fe3O4磁性颗粒在纤维中分散均匀,其与PAN是物理复合。纳米复合材料具有一定磁性,并可由磁性颗粒的加入量进行控制。     

Monodisperse α-Fe(2)O(3)@SiO(2)@Au core/shell nanocomposite spheres: synthesis, characterization and properties

A new hybrid spherical structure α-Fe(2)O(3)@SiO(2)@Au with a size of about 141?nm was designed, with a hematite cubic core surrounded by a thick silica shell and further decorated with gold nanoparticles. The monodisperse α-Fe(2)O(3)@SiO(2) spheres were first prepared by a sol-gel process based on the modified St?ber method. Subsequently, the surface of the α-Fe(2)O(3)@SiO(2) particles was functionalized by-NH(2) functional groups. The electrostatic attraction of -NH(2) groups will attach the negatively charged Au nanoparticles to the amino-functionalized α-Fe(2)O(3)@SiO(2) nanospheres in order to prepare α-Fe(2)O(3)@SiO(2) monodisperse hybrid spheres. The M(H) hysteresis loop for α-Fe(2)O(3)@SiO(2) and α-Fe(2)O(3)@SiO(2)@Au spheres indicates that the nanocomposite spheres exhibit superparamagnetic characteristics at room temperature. The optical properties and the application of these hybrid nanocomposites as catalysts for the conversion of CO to CO(2) have also been studied.     

Preparation of composite nanofibers containing gold nanoparticles by using poly(N-vinylpyrrolidone) and β- cyclodextrin

We report a new method for preparing β-cyclodextrin/poly(N-vinylpyrrolidone) composite nanofibers containing gold nanoparticles by electrospinning. β-Cyclodextrin is mixed into fibers as a new material, and it acts as stabilized reagent and reducing reagent in the synthesis of gold nanoparticles. TEM observation confirms that the gold nanoparticles are completely encapsulated within the composite nanofibers.     

A novel electrospun silk fibroin/hydroxyapatite hybrid nanofibers

A novel electrospinning of silk fibroin/hydroxyapatite hybrid nanofibers with different composition ratios was performed with methanoic acid as a spinning solvent. The silk fibroin/hydroxyapatite hybrids containing up to 30% hydroxyapatite nanoparticles could be electrospun into the continuous fibrous structure. The electrospun silk fibroin/hydroxyapatite hybrid nanofibers showed bigger diameter and wider diameter distribution than pure silk fibroin nanofibers, and the average diameter gradually increased from 95 to 582 nm. At the same time, the secondary structure of silk fibroin/hydroxyapatite nanofibers was characterized by X-ray diffraction, Fourier transform infrared analysis, and DSC measurement. Comparing with the pure silk fibroin nanofibers, the crystal structure of silk fibroin was mainly amorphous structure in the hybrid nanofibers. X-ray diffraction results demonstrated the hydroxyapatite crystalline nature remained as evidenced from the diffraction planes (002), (211), (300), and (202) of the hydroxyapatite crystallites, which was also confirmed by Fourier transform infrared analysis. The thermal behavior of hybrid nanofibers exhibited the endothermic peak of moisture evaporation ranging from 86 to 113 °C, and the degradation peak at 286 °C appeared. The SF/HAp nanofibers mats containing 30% HAp nanoparticles showed higher breaking tenacity and extension at break for 1.1688 ± 0.0398 MPa and 6.55 ± 1.95%, respectively. Therefore, the electrospun silk fibroin/hydroxyapatite hybrid nanofibers should be provided potentially useful options for the fabrication of biomaterial scaffolds for bone tissue engineering.     

Dispersion characteristics and properties of poly(methyl methacrylate)/multi-walled carbon nanotubes nanocomposites

The preparation, characterization, and properties of poly(methyl methacrylate) (PMMA)/multi-walled carbon nanotubes (MWCNTs) nanocomposites are described. Nanocomposites have been prepared by melt-blending in a batch mixer. Both unmodified and surface modified MWCNTs have been used for the nanocomposites preparation. Using both unmodified and modified MWCNTs, the effect of surface modification in nanocomposites is investigated by focusing on three major aspects: dispersion characteristics, mechanical properties, and electrical conductivity measurements. Dispersion of the MWCNTs in the PMMA matrix is examined by scanning and transmission electron microscopy that revealed a homogeneous distribution-dispersion of MWCNTs in the PMMA matrix for both unmodified and modified MWCNTs. Thermomechanical behavior is studied by dynamic mechanical analyzer and results showed a substantial improvement in the mechanical properties of PMMA in conjunction to an increase in the elastic behavior. The tensile properties of neat PMMA moderately improved after nanocomposites preparation with both modified and unmodified MWCNTs, however, electrical conductivity of neat PMMA significantly improved after nanocomposites preparation with 2 wt% unmodified MWCNTs. For example, the through plane conductivity increased from 3.6 x 10(-12) S x cm(-1) for neat PMMA to 3.6 x 10(-9) S x cm(-1) for nanocomposite. The various property measurements have been conducted and results have shown that, in overall, surface modifications have very little or no effect on final properties of neat PMMA.     

静电纺纤维素纳米晶体/壳聚糖-聚乙烯醇复合纳米纤维的制备与表征

通过探索纤维素纳米晶体（CNC）添加量对壳聚糖-聚乙烯醇（CS-PVA）基体性能的影响,为静电纺CNC/CS-PVA复合纳米纤维的制备提供理论支撑。以CNC、CS和PVA为原料,采用静电纺丝法成功制备不同CNC含量（质量分数）的静电纺CNC/CS-PVA复合纳米纤维,并通过SEM、TGA和FTIR等分析手段对CNC/CS-PVA复合纳米纤维的微观结构和性能进行了表征。结果表明：添加CNC后静电纺CNC/CS-PVA复合纳米纤维直径变大,表面变粗糙,力学性能和热学性能提高;随着CNC含量的增加,静电纺CNC/CS-PVA纤维的杨氏模量（E）和抗拉强度（σ）先增强后减弱,而外延起始温度继续上升。当CNC含量为3wt%时,静电纺CNC/CS-PVA复合纳米纤维力学性能最好,相比于CS-PVA复合纳米纤维,E和σ分别提高了43.9%和24.8%;当CNC含量为20wt%时,静电纺CNC/CS-PVA复合纳米纤维直径分布不均匀,可以观察到单根纤维表面存在少量的球状结构物质,同时外延起始温度达到328.83℃;FTIR分析得出,CNC与CS和PVA之间只存在分子间的相互作用而没有发生化学反应;随着溶液的酸性减弱,碱性增强,不同CNC含量的静电纺CNC/CS-PVA复合纳米纤维稳定性逐渐提高,而CNC含量对其稳定性影响不大。