Synthesis and characterization of immobilized PAMAM dendrons

Controllable Fabrication of Hydrophilic Surface Micro/Nanostructures of CFRP by Femtosecond Laser

Carbon fiber reinforced polymer (CFRP), a highly engineered lightweight material with superior properties, is widely used in industrial fields, such as aerospace, automobile, and railway transportation, as well as medical implants and supercapacitor. This work presents an effective surface treatment method for the controllable fabrication of hydrophilic surface micro/nanostructures of CFRP through femtosecond laser processing. Selective removal of the epoxy resin and leaving the carbon fibers exposed are achieved when CFRP is weakly ablated by a femtosecond laser. The diameters and structures of the carbon fibers can be controlled by adjusting the laser processing parameters. Three-dimensional surface micro/nanostructures are processed when CFRP is strongly ablated by a femtosecond laser. Meanwhile, the transformation of the sp2 orbitals to sp3 orbitals of graphitic carbons of carbon fibers is induced by a femtosecond laser. Moreover, the investigation of surface roughness and wettability of femtosecond laser-processed CFRP indicates increased roughness and excellent hydrophilicity (a contact angle of 28.1°). This work reveals the effect of femtosecond laser processing on the regulation of the physicochemical properties of CFRP, which can be applicable to surface treatment and performance control of other fiber-resin composites. The excellent hydrophilicity will be conducive to the combination of CFRP with other materials or to reducing the friction resistance of CFRP used in medical implants.

Copper(I)-alkylamine mediated synthesis of copper nanowires

Formation of a Cu(i)-alkylamine complex is found to be the key step for Cu(ii) ions to reduce to Cu(0) in the presence of glucose. Also, alkylamines in Cu nanowire synthesis serve triple roles as a reducing, complexation and capping agent. Alkylamines reduce Cu(ii) to Cu(i) at above 100 °C and protect the Cu(i) by forming a Cu ion-alkylamine coordination complex with a 1 : 2 ratio in an aqueous solution. With respect to the 1 : 2 complex ratio, the additional free alkylamines ensure a stable Cu(i)-alkylamine complex. After completion of Cu(i)-Cu(0) reduction by glucose, alkylamines remain on Cu(0) seeds to regulate the anisotropic growth of Cu nanocrystals. Long-chain (≥C16) alkylamines are found to help produce high-quality Cu nanowires, while short-chain (≤C12) alkylamines only produce CuO products. Furthermore, Cu nanowire synthesis is found to be sensitive to additional chemicals as they may destabilize Cu ion-alkylamine complexes. By comparing the Cu(i)-alkylamine and Maillard reaction mediated mechanism, the complete Cu nanowire synthesis process using glucose is revealed.

Effects of grafting low-generation poly(amido amine) onto carbon fiber surface by in situ polymerization on the mechanical properties of fiber composites

Low-generation poly(amido amine) (PAMAM)-grafted carbon fibers (CFs) emerged as a new reinforcement for improving the mechanical properties of fiber composites. In this work, hybrid reinforcement, which could greatly enhance the surface roughness and wettability of CF, was prepared via growing PAMAM onto fiber surface by in situ polymerization.The modified surface morphology and chemical composition were investigated by scanning electron microscopy, atomic force microscopy, dynamic contact angle analysis test, and X-ray photoelectron spectroscopy. Experimental results indicated PAMAM dendrimers grown on the CF significantly enhanced interfacial properties of the resulting composites. In addition, compared with the desized CF composites, the CF grafted with PAMAM composites exhibited 34.65% enhancement in the interfacial shear strength.

Low-Temperature Oxidation-Free Selective Laser Sintering of Cu Nanoparticle Paste on a Polymer Substrate for the Flexible Touch Panel Applications

Copper nanomaterials suffer from severe oxidation problem despite the huge cost effectiveness. The effect of two different processes for conventional tube furnace heating and selective laser sintering on copper nanoparticle paste is compared in the aspects of chemical, electrical and surface morphology. The thermal behavior of the copper thin films by furnace and laser is compared by SEM, XRD, FT-IR, and XPS analysis. The selective laser sintering process ensures low annealing temperature, fast processing speed with remarkable oxidation suppression even in air environment while conventional tube furnace heating experiences moderate oxidation even in Ar environment. Moreover, the laser-sintered copper nanoparticle thin film shows good electrical property and reduced oxidation than conventional thermal heating process. Consequently, the proposed selective laser sintering process can be compatible with plastic substrate for copper based flexible electronics applications.

Enhanced Electrocatalytic Activities of PtCuCoNi Three-Dimensional Nanoporous Quaternary Alloys for Oxygen Reduction and Methanol Oxidation Reactions

Control of morphology and composition could precisely and efficiently alter the catalytic properties of Pt-based materials, improving the electrocatalytic activity and durability. Here we proposed a rapid, controllable synthesis of three-dimensional PtCuCoNi quaternary alloys with low Pt-group metal, which were directly synthesized by reducing metal precursors in aqueous solution. The resultant quaternary alloys show excellent oxygen reduction and methanol oxidation reaction activities in acid solution. By rational tuning of the composition of PtCuCoNi alloys, they achieved a mass activity of 0.72 A/mgPt on the basis of Pt mass for oxygen reduction reaction. Moreover, the durability is also higher than that of commercial Pt/C catalyst. These PtCuCoNi quaternary alloys characterized by three-dimensional porous nanostructures hold attractive promise as substitutes for carbon-supported Pt catalysts with improved activity and stability.

PtCu bimetallic alloy nanotubes with porous surface for oxygen reduction reaction

PtCu bimetallic alloy nanotubes with porous surface were synthesized in aqueous solution using Te NWs as templates. The nanotubes with optimized composition present enhanced electrocatalytic performance for oxygen reduction reaction.

Thermoelectric properties of nanocrystalline Cu3SbSe4 thin films deposited by a self-organized arrested precipitation technique

Ternary Cu₃SbSe₄ thin films prepared by an arrested precipitation technique using non-toxic tartaric acid exhibit good thermoelectric properties.

Grafting of poly-L-lysine dendrigrafts onto polypropylene surface using plasma activation for ATP immobilization - Nanomaterial for potential applications in biotechnology

The present work describes a new environmental friendly strategy for the development of surfaces with high amine density via the grafting of native or modified poly-L-lysine dendrigraft (DGL G3) onto plasma activated polypropylene (PP), polystyrene (PS), polyimide, and polytetrafluoroethylene (PTFE) surface. Modified DGL G3 was prepared by replacement of few peripheral amines by various functionalities. Grafting efficiency was determined by wettability measurements, IRTF, XPS, AFM, and by colorimetry using optimized Coomassie Brilliant Blue method tailored for surface analysis. It was shown that a 4-7nm DGL G3 monolayer with 4×10(14)aminecm(-)(2) was covalently grafted onto various surfaces. Immobilization of adenosine triphosphate on the DGL-g-PP material from dilute solution was studied by bioluminescence and proved the ability of the material to interact with polyanionic biological compounds: 1 ATP complex with 5 amine groups. So, this material has a potential use in diagnostic and more widely for biotechnology due to its high capacity for biomolecule immobilization.