Metal-polymer Hybrid Research Articles

One-pot green synthesis of gold nanoparticles and its supportive role in surface activation of non-woven fibers as heterogeneous catalyst

Development of eco-friendly and sustainable approaches for the synthesis of metallic nanoparticles are elucidating extensive research in the emerging interdisciplinary field of nanotechnology. Herein, we demonstrate a complete green chemistry and atom-economy route for the rapid production of noble metal-based nanoparticles by utilizing an aqueous extract solution of Chinese native Osmanthus fragrans leaves as reducing and capping agent, irradiated by natural sunlight. Success in the generation of gold nanoparticles (AuNPs) was initially monitored by optical absorption spectroscopy showing the surface plasma resonance (SPR) band around ca. 545 nm range. The size and morphology of AuNPs were controlled and systematically characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), and atomic force microscopy (AFM). Furthermore, the composition of the gold element was assured by energy dispersive X-ray spectroscopy (EDS). The crystallinity state and purity of AuNPs specimen was demonstrated by X-ray diffraction examination. Studying the infrared spectroscopy (FT-IR) revealed the presence of biomolecules on the surface of particles that are responsible for the reduction and stabilization process. Moreover, by adopting the metal-polymer hybrid synthetic approach for surface activation, in situ reduction of AuNPs on non-woven cellulosic fibers acted as support and facilitated catalytic reduction of p-nitrophenol to p-aminophenol via hydrogenation reaction in the presence of NaBH4. The micro-nanocomposite fibers are found advantageous in quick and energy-free recovery and stayed stable for numerous cycles. Overall, exclusion of toxic chemicals by the inclusion of plant extract as reducing agent and photo-energy as a driving force for the generation of AuNPs in aqueous medium makes this process eco-friendly, sustainable and economically viable for large-scale production.

Experimental and numerical investigation on the strength of polymer-metal hybrid with laser assisted metal surface treatment

The aim of this study was to evaluate the effect of laser assisted treating metal surface on the strength of polymer-metal hybrid. The oxide film on the metal surface was removed by caustic soda and nitric acid solution. After that, the metal surface was treated by fiber laser, and the hot pressing connection between polymer and metal was completed by plate vulcanizing machine. And then, the tensile strength was obtained by using universal testing machine. The effect of different laser power, different scanning line width and different scanning speed on the bonding strength of polymer-metal hybrid was investigated. The correlation between the characteristics of metal surface and the bonding strength of polymer-metal hybrid was analyzed based on the micro structure morphology and scanning electron microscope (SEM). The results show that the bonding strength of polymer-metal hybrid increases first and then decreases with the increase of laser power. With the increase of scanning line width, the strength of polymer-metal hybrid increases. When the scanning speed is 500 mm/s, the strength of polymer-metal hybrid is the lowest. Based on the experiment, a simplified model is established and analyzed. Through using ABAQUS to conduct the numerical simulations, the results are consistent with the theoretical analysis and experimental data.

Evaluation of Joint Formation and Mechanical Performance of the AA7075-T6/CFRP Spot Joints Produced by Frictional Heat.

The development of lightweight hybrid metal–polymer structures has recently attracted interest from the transportation industry. Nevertheless, the possibility of joining metals and polymers or composites is still a great challenge. Friction Spot Joining (FSpJ) is a prize-winning friction-based joining technique for metal–polymer hybrid structures. The technology is environment-friendly and comprises very short joining cycles (2 to 8 s). In the current work, aluminum alloy 7075-T6 and carbon-fiber-reinforced polyphenylene sulfide (CF-PPS) friction spot joints were produced and evaluated for the first time in the literature. The spot joints were investigated in terms of microstructure, mechanical performance under quasi-static loading and failure mechanisms. Macro- and micro-mechanical interlocking were identified as the main bonding mechanism, along with adhesion forces as a result of the reconsolidated polymer layer. Moreover, the influence of the joining force on the mechanical performance of the joints was addressed. Ultimate lap shear forces up to 4068 ± 184 N were achieved in this study. A mixture of adhesive–cohesive failure mode was identified, while cohesive failure was dominant. Finally, a qualitative comparison with other state-of-the-art joining technologies for hybrid structures demonstrated that the friction spot joints eventually exhibit superior/similar strength than/to concurrent technologies and shorter joining times.

Single-side resistance spot joining of polymer-metal hybrid structures

A new approach for resistance spot welding of hybrid polymer-metal components in overlap joint configuration is shown in this paper. The effect of welding current on the joining zone is demonstrated based on different process parameters. The results were transferred to a model concept of the joining zone geometry depending on current density and electrode arrangement. Furthermore, different surface conditions (corundum blasting, laser structuring) were applied and evaluated regarding mechanical properties.

Interfacial interaction and joining property of direct injection-molded polymer-metal hybrid structures: A molecular dynamics simulation study

Polymer-metal hybrid structures have been increasingly used to replace metallic components. Direct injection joining is one of the most promising technologies in fabricating polymer-metal hybrid structure. In this study, molecular dynamics method was used to study the interfacial interaction and joining property. Interfacial models with different surface structures on aluminum (Al) substrate were constructed. The influences of surface structure, non-bonded interaction strength, and pull-out force during the separation were systematically explored. Simulation results show that an obvious difference in polymer structure along z-axis is observed during the joining process. Influenced by the interfacial interaction, the atomic density is at its largest near the interface. As the separation continues, growing voids are observed near the interface. Polymer chains close to the Al substrate are greatly stretched, while the chains far away from the interface are relatively steady. Nevertheless, the changes in radius of gyration during the separation are much higher regardless of the substrate structures. The contact area mainly contributes to the interaction energy, whereas the mechanical interlocking formed in the undercut area contributes to the maximum inner force and work of separation. Moreover, the interfacial interaction is also affected by the non-bonded interaction strength and the pull-out force.

Metal nanowire–polymer matrix hybrid layer for triboelectric nanogenerator

In this work, we studied the surface potential of a metal–polymer hybrid layer and its effect on the performance of a triboelectric nanogenerator (TENG). Ag nanowires (AgNWs) separately embedded in two different polymers–one with a positive tribopotential and the other with a negative tribopotential–were prepared as model hybrid systems. The surface potentials of the hybrid system were systematically investigated by Kelvin probe force microscopy. The results demonstrated that each component of the hybrid layer affected the other component because of the difference in their work functions. The following two important findings were obtained. First, the surface potential of each polymer shifted drastically toward that of Ag and the surface potential of Ag shifted toward that of each polymer. Second, higher density of AgNWs led to higher Ag-induced charge density in the polymer, which consequently resulted in larger shift in the surface potential of the polymer. TENG performance measurements revealed that the tribopotential difference between the contact surfaces of the AgNW–polymer hybrid layer and the perfluoroalkoxy alkane (or Nylon) used as the top triboelectric layer governed the TENG performance. Our systematic investigation of the surface potential of a hybrid surface consisting of two materials with different surface potentials provides insight into the design of triboelectric layers for high-performance TENGs.

Achieving Better Greenhouse Effect than Glass: Visibly Transparent and Low Emissivity Metal-Polymer Hybrid Metamaterials

Achieving Better Greenhouse Effect than Glass: Visibly Transparent and Low Emissivity Metal-Polymer Hybrid Metamaterials

Irradiation Effects on Polymer-Grafted Gold Nanoparticles for Cancer Therapy.

In the context of cancer treatment, gold nanoparticles (AuNPs) are considered as very promising radiosensitizers. Here, well-defined polymer-grafted AuNPs were synthesized and studied under gamma irradiation to better understand the involved radiosensitizing mechanisms. First, various water-soluble and well-defined thiol-functionalized homopolymers and copolymers were obtained through atom transfer radical polymerization. They were then used as ligands in the one-step synthesis of AuNPs, which resulted in stable hybrid metal-polymer nanoparticles. Second, these nano-objects were irradiated in solution by γ rays at different doses. Structures were fully characterized through size exclusion chromatography, small-angle X-ray scattering, and small-angle neutron scattering measurements, prior to and after irradiation. We were thus able to quantify and to localize radiation impacts onto the grafted polymers, revealing the production sites of reactive species around AuNPs. Both external and near-surface scissions were observed. Interestingly, the ratio between these two effects was found to vary according to the nature of polymer ligands. Medium-range and long-distance dose enhancements could not be identified from the calculated scission yields, but several mechanisms were considered to explain high yields found for near-surface scissions. Then cytotoxicity was shown to be equivalent for both nonirradiated and irradiated polymer-grafted NPs, which suggested that released polymer fragments were nontoxic. Finally, the potential to add bioactive molecules such as anticancer drugs has been explored by grafting doxorubicin onto the polymer corona. This may lead to nano-objects combining both radiosensitization and chemotherapy effects. This work is the first one to study in details the impact of radiation on radiosensitizing nano-objects combining physical, chemical, and biological analyses.

A Room‐Temperature High‐Conductivity Metal Printing Paradigm with Visible‐Light Projection Lithography

AbstractFabricating electronic devices require integrating metallic conductors and polymeric insulators in complex structures. Current metal‐patterning methods such as evaporation and laser sintering require vacuum, multistep processes, and high temperature during sintering or postannealing to achieve desirable electrical conductivity, which damages low‐temperature polymer substrates. Here reports a facile ecofriendly room‐temperature metal printing paradigm using visible‐light projection lithography. With a particle‐free reactive silver ink, photoinduced redox reaction occurs to form metallic silver within designed illuminated regions through a digital mask on substrate with insignificant temperature change (<4 °C). The patterns exhibit remarkably high conductivity achievable at room temperature (2.4 × 107 S m−1, ≈40% of bulk silver conductivity) after simple room‐temperature chemical annealing for 1–2 s. The finest silver trace produced reaches 15 µm. Neither extra thermal energy input nor physical mask is required for the entire fabrication process. Metal patterns were printed on various substrates, including polyethylene terephthalate, polydimethylsiloxane, polyimide, Scotch tape, print paper, Si wafer, glass coverslip, and polystyrene. By changing inks, this paradigm can be extended to print various metals and metal–polymer hybrid structures. This method greatly simplifies the metal‐patterning process and expands printability and substrate materials, showing huge potential in fabricating microelectronics with one system.

Direct injection molding and mechanical properties of high strength steel/composite hybrids

Metal polymer hybrid technology is a promising way of automotive weight reduction and safety improvement. In this study, high strength steel and glass-fiber reinforced PA66 composite were integrated by direct injection molding process. The mechanical properties and failure behavior of steel/composite hybrids under tension, bending, mode I and II fracture loads were investigated experimentally, theoretically and numerically. The properties of the interface between steel and composite were measured using double cantilever beam and end-notched flexure tests for the first time. The analytical model and finite element simulation considering the interface mechanical behavior were proposed and validated. They can be utilized to predict the mechanical properties and progressive failure process of hybrid material cost-effectively and accurately. It is found that the cracks initiate at the interface, and then propagate through composite until the hybrid material loses load-carrying capacity completely. The steel dominates the load-bearing capacity, and the interface dominates the failure process. The results obtained in this study offer a scientific guidance and theoretical basis for the engineering application of metal polymer hybrid materials.

In-situ formation of polymer stabilized copper nanoparticles: A hybrid system with non-volatile switchable resistive property

In this report, we discuss about the preparation of a metal-polymer hybrid system (poly-aminosalicylic acid encapsulated copper nanoparticles) using an in-situ method, where the copper sulphate and aminosalicylic acid were used as the precursors for the metal and the polymer, respectively. The composite system was used as an active material for a device to demonstrate the electrical property. The system exhibited a nonvolatile switchable resistive behaviour with a constant ON-OFF current ratio of 2 × 103. The current-voltage behaviour of the metal-polymer based device was followed by the Poole-Frenkelemission and ohmicconduction mechanism.

Experimental and numerical investigations on low-velocity impact response of high strength steel/composite hybrid plate

Low-velocity impact tests were carried out on steel/short glass-fiber reinforced thermoplastic hybrid plates fabricated by a direct injection molding process. The impact response such as absorbed energy, peak force, dent depth and damage area was studied. A finite element model based on the data obtained from the dynamic and static tests of the constituent materials has been proposed to predict the response and failure behavior of hybrid plates under low-velocity impact loading, which is validated by comparing experimental results. Using the validated model, the damage process of the thin interface between steel and composite was analyzed conveniently and cost-effectively. It is found that the plastic deformation of steel, the fracture of composite and the interface delamination are three main failure modes. After the minor plastic deformation of constituent materials, the interface delamination occurred and propagated rapidly. In addition, the finite element model is developed successfully to investigate the effects of the impact velocity, the incident angle as well as the constituent material thickness on the impact behavior of hybrid plates. The results obtained in this study can support the design and optimization of load-bearing metal-polymer hybrid (MPH) structures.

Warpage and bending behavior of polymer–metal hybrids: experimental and numerical simulations

In this study, the amount of warpage occurring in a polymer–metal hybrid during its manufacturing process and the mechanical properties of the warped hybrid under bending load were investigated both experimentally and numerically. The cohesive zone model was employed to define contact between the polymer and the metal layer which the cohesive parameters were obtained from experimental tests. The effect of different injection process parameters including packing time, injection time, and melt temperature on the amount of warpage was also investigated. The results showed that the amount of warpage decreases by increasing injection time and increases by boosting melt temperature. Moreover, the results indicated that the amount of warpage decreases and then remains approximately constant as packing time is increased. In addition, packing time and melt temperature have the greatest impact on the amount of warpage. The results showed that there is a good agreement between simulated and experimental warpage and also between bending modulus obtained from experimental tests and simulation.

An Extended Kalman Filter as an Observer in a Control Structure for Health Monitoring of a Metal–Polymer Hybrid Soft Actuator

This paper presents an innovative nonlinear model of a self-sensing soft actuator and a switching extended Kalman filter, which is used as an observer for health monitoring such as a virtual sensor. Hardware-in-the-loop simulations and measurements justify the observation strategy. An adaptive position control structure based on the discrete wavelet packets transform method is proposed. Stimulus-responsive polymers are relevant for the realization of smart systems (capable of both sensing and actuating) in the context of soft actuators, for example, in bioinspired robotics, orthotic, and prosthetic technology. A real-time implementation of health monitoring techniques is important to guarantee a gentle, fault-free operation of the soft actuator in the presence of loads. The presented case shows a microrobotic application and measured results show the effectiveness of the developed observer regarding the soft actuator temperature to guarantee its longevity. The latter is necessary for normal operation without a test bench, because the states cannot be measured, but they need to be known for the implementation of the proposed health monitoring algorithms.

Cathode Nanostructuring and Separator Modification for High-Performance Lithium-Sulfur Batteries

Battery technologies involving Li-S chemistry are promising approaches to realize inexpensive and high energy density storage for sustainable energy applications. However, current Li-S batteries still suffer from short life-time due to active material loss through the soluble polysulfide molecules shuttling between battery cathode and anode.[1] We present herein our recent advances in the understanding of the electrochemical reactions at Li-S battery cathode and addressing the shuttle effect by polysulfide trapping. Specifically, an in-operando characterization technique based on optical microscopy is developed to intuitively visualize the selective deposition of sulfur and Li2S in battery cathodes, and the critical roles of current collectors and additives, including different metals and semiconductors, are demonstrated. Accordingly, innovative cathode architectures are designed to control the oriented deposition and diffusion of sulfur-containing species. In particular, an ultrathin and compact blocking layer of 2D MoS2 and WS2 nanoflakes, with a thickness of ca. 15 nm, are deposited on separator through a solution based self-assembly method,[2] which effectively adsorb polysulfide molecules and thus suppress their diffusion to the battery anode. In addition, Li2S-metal composites and polymer-metal hybrid networks are fabricated as hosts for sulfur cathodes to enable rapid battery charge-discharge processes given the large active surface area and better control of charge (or discharge) product deposition.[3] Combining these two strategies, we report greatly enhanced specific capacity (over 1200 mAh g-1) and cyclability (over 500 cycles) for the nanostructured sulfur cathodes compared to the conventional carbon-sulfur based cathode, and the routes to further improving high-energy and long-life Li-S battery are discussed. [1] Seh, Z. W.; Sun, Y.; Zhang, Q.; Cui, Y. Chem. Soc. Rev. 2016, 45, 5605. [2] Yu, X.; Prévot, M. S.; Guijarro, N.; Sivula, K. Nat. Commun. 2015, 6, 7596. [3] Zhou, G. M.; Sun, J.; Jin, Y.; Chen, W.; Zu, C. X.; Zhang, R. F.; Qiu, Y. C.; Zhao, J.; Zhuo, D.; Liu, Y. Y.; Tao, X. Y.; Liu, W.; Yan, K.; Lee, H. R.; Cui, Y. Adv. Mater. 2017, 29, 1603366

Huge Enhancement of Luminescence from a Coaxial-Like Heterostructure of Poly(3-methylthiophene) and Au.

Recently, the light-matter interaction at nanoscale has attracted great interest from physicists, chemists and material scientists, as it gives peculiar optical properties that couldn’t be observed at the bulk scale. The synthesis and characterization of organic-inorganic heterostructures forming quantum dots, nanowires or nanotubes provide opportunities to understand their photophysical mechanism and to apply optoelecronic devices. Herein, we report a huge enhanced luminescence in a coaxial-like heterostructured poly (3-methylthiophene) (P3MT) with Au. We electrochemically synthesized P3MT nanowires (NWs) on a nanoporous template, and sequentially deposited Au on the surface of P3MT NWs. The diameter of heterostructured P3MT/Au NWs was about 200 nm, where the cladding-shape Au were about 10 nm. The visible range absorbance, with two new absorption peaks of P3MT/Au NWs, was significantly increased compared with that of P3MT NWs. Accordingly, the photoluminescence (PL) of a P3MT/Au NW was enormously increased; up to 170 times compared to that of P3MT NWs. More interestingly, an unexpected enhancement of PL was observed from cross-junction point of P3MT/Au NWs. The abnormal PL properties of P3MT/Au NWs were attributed to the charge transfer and the surface plasmon resonance between the cladding-shape Au and the core-shape P3MT, which resulted in the enhanced quantum yield. This incites us to reconsider the light-matter interaction in polymer-metal hybrid structures applicable for high-performance optoelectronic devices.

Experimental investigation into metal micro-patterning by laser on polymer-metal hybrid joining

Surface modification pretreatment on laser direct joining of glass fibre reinforced polyamide to steel was studied to assess its effect on the joint's mechanical performance. The steel part was structured by laser radiation to accomplish a proper mechanical interlock when joining with the polymer. In a second step, the opposite side of the micro-structured metal was irradiated by a continuous wave (cw) fibre laser system until reaching the melting temperature of the polymer in both materials interface. The metal micro-structuring was produced by two different laser sources (nanosecond pulses (ns) and cw) in order to study the effect of different groove geometries on the joint's failure force under tensile-shear tests. The impact of structure density and clamping pressure was also assessed. A tight dependence of aspect ratio and recast material height of patterns on joint’s failure force was found for the micro-patterns that were produced by nanosecond pulses. The greatest strength was achieved in the case of patterns produced by ns-pulses. The trend concerning the effect of structure density was validated for the patterns that were produced by ns-pulses and cw-radiation. The changes in clamping pressure did not evidence a significant influence on the joint quality. The morphological features of the detached surfaces showed that the micro-geometric structure aspect ratio has a meaningful effect on the failure mode in the case of structures that were generated by nanosecond pulses.

Aluminum/polypropylene composites produced through injection molding

The contact angles of molten polypropylene on metals with different surface conditions were examined. A quantitative relation between the surface topography and mechanical strength as well as the optimum dimensional scope of the topography feature for achieving good mechanical performance was determined. High metal temperatures facilitated the filling of the surface features by the polymer melt. The interfacial strength between the metal surface and polymer was dramatically improved by increasing the metal temperature approximately to the heat-distortion temperature of polypropylene. The fracture mechanism of the polymer-metal hybrid structures as well as the correlation between the crystallinity of polypropylene near the interface and the bonding strength was examined. The β-crystals were found to have a significant effect on the mechanical performance of the polymer-metal hybrid structures.

AddJoining: A novel additive manufacturing approach for layered metal-polymer hybrid structures

A novel assembling technique based on additive manufacturing and materials joining principles has been introduced for layered metal-polymer hybrid structures. The AddJoining technique produces layered hybrid structures, using polymer 3D printing methods. The feasibility of the technique was demonstrated using fused deposition modeling for single-lap joint configuration. Microstructure and mechanical strength of the joints were studied using two combinations of materials; aluminum 2024-T3 with acrylonitrile butadiene styrene and aluminum 2024-T3 with alternate layers of polyamide-6 and carbon-fiber-reinforced polyamide-6. The latter reached an average ultimate lap-shear strength of 21.9 ± 1.1 MPa, showing 19% superior performance to the adhesively bonded joints. This exploratory investigation showed the potential of AddJoining to produce metal-polymer layered structures.

React‐on‐Demand (RoD) Fabrication of Highly Conductive Metal–Polymer Hybrid Structure for Flexible Electronics via One‐Step Direct Writing or Printing

AbstractAs a fast prototyping technique, direct writing of flexible electronics is gaining popularity for its low‐cost, simplicity, ultrahigh portability, and ease of use. However, the latest handwritten circuits reported either have relative low conductivity or require additional post‐treatment, keeping this emerging technology away from end‐users. Here, a one‐step react‐on‐demand (RoD) method for fabricating flexible circuits with ultralow sheet resistance, enhanced safety, and durability is proposed. With the special functionalized substrate, a real‐time 3D synthesis of silver plates in microscale is triggered on‐demand right beneath the tip in the water‐swelled polyvinyl alcohol (PVA) coating, forming a 3D metal–polymer hybrid structure of ≈7 µm with one single stroke. The as‐fabricated silver traces show an enhanced durability and ultralow sheet resistance down to 4 mΩ sq−1 which is by far the lowest sheet resistance reported in literatures achieved by direct writing. Meanwhile, PVA seal small particles inside the film, adding additional safety to this technology. Since neither nanomaterials nor a harsh fabrication environment are required, the proposed method remains low cost, user friendly, and accessible to end users. With little effort, the RoD approach can be extended to various printing systems, offering a particle‐free, sintering‐free solution for high‐resolution, high‐speed production of flexible electronics.