Graphene

Hydrogen embrittlement (HE) is an epidemic problem for high strength medium carbon low alloy steel causing reduction in mechanical strength and useful service lifetime. Hydrogen embrittlement of high strength steel is concern for various industrial components used in critical applications. Unpredictable & sudden failure of mechanical equipment/components made of high strength steel (HSS) below designed allowable stress and without appreciable deformation resulted in many catastrophic accidents. HSS being used in various engineering applications such as Aerospace, Nuclear, Marine and Transportation etc. Components typically affected by hydrogen embrittlement are pressure vessels, boilers, automobile frame, fasteners & hardware, shafts, axles, rotors, pipelines etc. Extensive research has been done by scientists & engineers to explore various ways to prevent hydrogen embrittlement. Some of them are i) addition of alloying elements ii) selection of material with less susceptibility to hydrogen iii) use of barrier layers to prevent hydrogen diffusion iv) change in manufacturing process and application environment v) use of advance Nano coatings to minimize hydrogen penetration etc. Out of all these methods of controlling hydrogen embrittlement, use of advance coatings appears to be more practical, less intricate and economical. In current decade Graphene has achieved a great attention from engineering world because of its excellent chemical, physical, mechanical & thermal properties. Graphene can act as a protective barrier against many environmental induced degradation of alloy steels because of its extraordinary impermeability. This review article summaries the current state of research & available commercial solutions for mitigations of hydrogen embrittlement using graphene based Nano-coatings. Authors have conducted experiments on several available coatings including graphene to investigate the behavior in an environment promoting hydrogen embrittlement and compared the effect on mechanical properties and ductility of high strength steel (EN24/AISI4340/34CrNiMo6)

In recent days, Polymer is very useful and important material for its unique properties and applications. A Polymer is a large molecule or macromolecule which is composed of several repeating subunits, called monomer. Polymers are classified depending on several parameters like chemical structure, polymeric structure, arrangement of monomer, tacticity etc. It has several applications in the field of industry, science and medical. Several properties of polymers can be tuned by embedding different materials with it. Among them graphene and carbon nanotube are most desirable material. Graphene is the latest discovery belonging to the group of carbon allotropes and a versatile material in nanotechnogy due to its unique electronic, optical and mechanical properties. It is a two dimensional material, a Single layer of graphite. It has several properties such as conductive, flexible, highly strong and transparent. On the other side, carbon nanotube is most valuable material in several applications for its unique electronic, mechanical and optical properties. Like graphene and graphite, it is also a carbon based material. Due to its high surface to volume ratio, even a low content of nanotube in polymer matrix can change the interphase or interface region which changes their properties significantly. The electromagnetism and microwave absorption properties of several material can be modified by incorporation of desired value of carbon nanotube with that material. Dielectric properties of several polymer materials also can be modified by embedding carbon nanotube with it. It is also acted as a filler material for introducing Piezoelectricity in some Polymer material. Here properties of polymer, graphene and carbon nanotube has been discussed in brief. Synthesis and applications of these three materials are also the key focus of this paper.

Polyurethane (PU) and its nanocomposites based gas barrier films and coatings have established a distinctive position among various technologically important materials due to their large-scale potential applications. This review aims at highlighting the gas barrier property of polyurethane nanocomposite (PUNC) based films, membranes and coatings containing platelet-shaped fillers such as clays and graphene in PU matrix. The other fillers such as CNT, POSS, metal nanoparticles and nanocellulose have also been reviewed for their contribution in improving gas barrier property of polymers. The probable transport-mechanism of small gas molecules through PU and PUNCs have been discussed. There is also a discussion on basic PU-chemistry and effect of structure and morphology of PU on its gas barrier property. Various factors which influence the gas permeability through PU and PUNC films and coatings have been scrutinized. Some aspects of improving the gas barrier property of PUNCs have also been discussed. An emphasis is given on various proposed models for prediction of gas permeability through polymer nanocomposites. It also reviews the existing literature related to modeling and prediction of gas permeability of different PUNC membranes, films and coatings. Finally, special attention has been paid to the potential industrial applications of PUNC based films and coatings.

In this review article we discuss the recent progress in studying ballistic transport for charge carriers in graphene through highly inhomogeneous magnetic field known as magnetic barrier in combination with gate voltage induced electrostatic potential. Starting with cases for a single or double magnetic barrier we also review the progress in understanding electron transport through the superlattices created out of such electromagnetic potential barriers and discuss the possibility of experimental realization of such systems. The emphasis is particularly on the analogy of such transport with propagation of light wave through medium with alternating dielectric constant. In that direction we discuss electron analogue of optical phenomena like Fabry–Perot resonances, negative refraction, Goos–Hänchen effect, beam collimation in such systems and explain how such analogy is going to be useful for device generation. The resulting modification of band structure of Dirac fermions, the emerg...

Silver nanoparticles (Ag NPs) play important roles in the development of plasmonic applications. Combining these nanoparticles with graphene can yield hybrid materials with enhanced light–matter interaction. Here, we report a simple method for the synthesis of graphene–silver nanoparticle hybrids on highly oriented pyrolytic graphite (HOPG) substrates. We demonstrate by scanning tunneling microscopy and local tunneling spectroscopy measurements the electrostatic n-type doping of graphene by contact with silver. We show by UV-Vis reflectance investigations that the local surface plasmon resonance (LSPR) of Ag NPs partially covered with graphene is preserved for at least three months, i.e., three times longer than the LSPR of bare Ag NPs. The gradual loss of LSPR is due to the spontaneous sulfurization of non-covered Ag NPs, as revealed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. We show that the Ag NPs completely sandwiched between graphene and HOPG do n...

Geopolymer is now a more advanced alternative to cement and available substitute for OPC while graphene nanoplatelets (GnP) are new nanomaterials with extraordinary properties that can enhance and improve the strength of cementitious materials. Although graphene reinforced concrete has intriguing potential, its implementation in construction requires better knowledge of the impact of GnP on the properties of concrete related to durability. Studies on the compressive and tensile strength performance of geopolymer concrete (GPC) containing GnP are needed. The present study investigated the influence of reinforcing GPC with varying percentages of GnP on the compressive and split tensile strengths of GPC. The addition of GnP ranged from 0.0%, 0.25% and 0.5% by weight of total binder. It has been observed that the addition of GnP increased the compressive strength by 30% and the tensile strength by 22% in comparison to a reference sample with a specified composition of fly ash and sodium metasilicate. In addition, the effect of GnP on enhancing the compressive strength of the geopolymer was shown to diminish as the amount of sodium metasilicate increased.

Environmental contamination and human exposure to dyes have dramatically increased over the past decades because of their increasing use in such industries as textiles, paper, plastics, tannery and paints. These dyes can cause deterioration in water quality by imparting color to the water and inducing the photosynthetic activity of aquatic organisms by hindering light penetration. Moreover, some of the dyes are considered carcinogenic and mutagenic for human health. Therefore, efficient treatment and removal of dyes from wastewater have attracted considerable attention in recent years. Photocatalysis, due to its mild reaction condition, high degradation, broad applied area and facile manipulation, is a promising method of solving environmental pollution problems. In this paper, we report the synthesis of graphene oxide-tin oxide (GO-SnO2) nanocomposite and the effectiveness of this composite in decolorizing Methylene Blue. Tin oxide was prepared by liquid phase co-precipitation meth...

A new way of making large sheets of high-quality, atomically thin graphene could lead to ultra-lightweight, flexible solar cells, and to new classes of light-emitting devices and other thin-film electronics. [45]
Graphene-based computer components that can deal in terahertz “could be used, not in a normal Macintosh or PC, but perhaps in very advanced computers with high processing rates,” Ozaki says. This 2-D material could also be used to make extremely high-speed nanodevices, he adds. [44]

A flexible graphene field-effect transistor (Gr-FET) biosensor for ultrasensitive and specific detection of miRNA without labeling and functionalization is reported. The flexible biosensor presents robust performance even after multiple cycles bending to cylinder with 8 mm radius. DNA probe is designed with partial segment complementary to target miRNA, and immobilized on the graphene surface though π-π stacking interaction. After capture of target miRNA, Dirac point shift in Gr-FET is induced, which shows a linear relationship with target miRNA concentration in semi-log scale. Gr-FET based biosensor finishes miRNA detection in 20 min, and is able to achieve a miRNA detection limit as low as 1 fM without any functionalization and labeling. The interaction processes of DNA-graphene and DNA-miRNA are confirmed through surface enhanced Raman scattering technology. The proposed biosensor will have prospective applications in wearable electronics for health monitoring and diseases diagnosis.

Apstrakt: Grafen je altrop ugljenika u obliku dvo-dimenzione rešetke debljine jednog atoma. Skoro je u potpunosti providan i istovremeno toliko gust da ni najmanji atomi gasa ne mogu da prođu kroz njega. Dobro provodi elektricitet, kao i bakar, i veoma je jak (100 puta je jači od čelika, a može da se rastegne i do 20%). Ujedno predstavlja najtanji i najjači poznati materijal. U radu su prikazane osnovna svojstva grafena i neke od varijanti njegove primene. Ključne reči: Grafen, ugljenik, nano-materijali, tranzistor od grafena (GT).
How to cite this article: Dašić, P. & Mirjanić, D.: Osnovna svojstva i primene grafena. U: Zborniku radova Naučnog skupa "Savremeni materijali" / Proceedings of the Conference "Contemporary Materials", Knjiga 35; Banja Luka, Republika Srpska, Bosna i Hercegovina; 9-10 novembar 2017. Banja Luka (Republika Srpska - Bosna i Hercegovina): Akademija nauka i umjetnosti Republike Srpske (ANURS) / Academy of Sciences and Arts of the Republic of Srpska, 2018, str. 557-568. ISBN 978-99938-21-98-4.

In photovoltaics, research is aiming to investigate new materials able to push the efficiency limit for solar cells towards the highest values without increasing the fabrication cost. This paper presents a review about graphene material and its potential use in all technological fields. Due to its high conductivity, transparency and amazing properties. It seems that it has an important place in the next generation of solar cells instead of silicon or thin film based solar cells, researchers found diverse applications for graphene in nanoelectronics, aviation, industry, transport, biomedecine and others. This paper present a review about the state of art about the graphene material in photovoltaic solar cells where very interesting efficiencies were recorded.

This article analyses research trials on noteworthy features and technological impact of the polystyrene/graphene nanoplatelet nanocomposites. In polystyrene matrix, graphene nanoplatelets have been used as remarkable nanofiller. Substantial improvements in polystyrene physical properties occurs by adding low nanofiller content. Simple in situ, emulsion, solution, or melt synthesis strategies have been used to develop polystyrene/graphene nanoplatelet nanocomposite. The polystyrene/graphene nanoplatelet nanocomposites possess enhanced structural features, morphology, glass transition temperature, thermal stability, mechanical strength, electrical characteristics, sensing, capacitance, and other physical properties. The performance of the polystyrene/graphene nanoplatelet nanocomposites have been explored for the practical applications in the fields of sensing, electromagnetic interference shielding, and flame retardant materials.

Now, research from University of Toronto Engineering shows that graphene is also highly resistant to fatigue-able to withstand more than a billion cycles of high stress before it breaks. [48] "The junctions were reproducible over several devices and operated from 20 Kelvin up to room temperature. Our approach represents a simple but powerful strategy for the future integration of molecule-based functions into stable and controllable nanoelectronic devices." [47] The team has turned graphene oxide (GO) into a soft, moldable and kneadable play dough that can be shaped and reshaped into free-standing, three-dimensional structures. [46] A team of researchers based at The University of Manchester have found a low cost method for producing graphene printed electronics, which significantly speeds up and reduces the cost of conductive graphene inks. [45] Graphene-based computer components that can deal in terahertz "could be used, not in a normal Macintosh or PC, but perhaps in very advanced computers with high processing rates," Ozaki says. This 2-D material could also be used to make extremely high-speed nanodevices, he adds. [44] Printed electronics use standard printing techniques to manufacture electronic devices on different substrates like glass, plastic films, and paper. [43] A tiny laser comprising an array of nanoscale semiconductor cylinders (see image) has been made by an all-A*STAR team. [42] A new instrument lets researchers use multiple laser beams and a microscope to trap and move cells and then analyze them in real-time with a sensitive analysis technique known as Raman spectroscopy. [41]

The Graph is a powerful mathematical tool applied in many fields as transportation, communication, informatics, economy, … In an ordinary graph, the weights of edges and vertexes are considered independently where the length of a path is the sum of weights of the edges and the vertexes on this path. However, in many practical problems, weights at a vertex are not the same for all paths passing this vertex but depend on coming and leaving edges. The presented paper develops a model of the extended linear multi-commodity multi-cost network that can be more exactly and effectively applied to model many practical problems. Then, maximal limit cost flow problems are modeled as implicit linear programming problems. On the base of dual theory in linear rogramming, an effective approximate algorithm is developed.

A new strategy for hydrogen sulfide removal by amido-functionalized reduced graphene oxide as a novel metal-free and highly efficient nanoadsorbent Rahighi (2015) A new strategy for hydrogen sulfide removal by amido-functionalized reduced graphene oxide as a novel metal-free and highly efficient nanoadsorbent, Journal of Sulfur Chemistry, 36:6, 660-671,

This thesis contains a theoretical treatment of the time-dependent quantum transport of electrons through molecular junctions. In particular, the nonequilibrium Green's function (NEGF) method is used to obtain the time-dependent current and current fluctuations in response to an arbitrarily time-dependent spatially homogeneous bias in the leads and molecular region. All subsystems in the nanojunction are assumed to be noninteracting throughout, and in addition the wide-band limit approximation (WBLA) is made in order to simplify the treatment of the lead-molecule coupling.

The theoretical work involves a complete analytical solution in the two-time plane of the Kadanoff-Baym equations for all components of the molecular region Green's function defined on the imaginary time Konstantinov-Perel' contour. This enables the derivation of expressions for time-dependent quantities such as the particle number in the molecular region and a generalized time-dependent Landauer-Büttiker (LB) formula for the current through an arbitrarily large conducting molecule. The partition-free approach is assumed for the switch-on of a bias in the leads, which enables us to study the effects on the transient transport of the initial coupling between the subsystems of the nanojunction.

The analytical expression for the full two-time Green's function is then used to study the quantum correlations between currents in the different leads. Using many-body methods, the two-time current correlation function is expressed in terms of a matrix product of Green's functions which are all known exactly. Therefore, in similar fashion to the generalized LB current, the current correlations generalize the LB theory of shot and thermal noise so that it is (i) partition-free and (ii) valid for an arbitrary time-dependent bias. To check its generality, this formula is shown to reproduce results for the zero- and finite-frequency current noise that are known from the literature on this topic.

The formulas for the current and current fluctuations are originally obtained in terms of integrals over the frequency and time planes. To render these formulas useful for calculations on large molecules they are then re-expressed with all frequency integrals replaced with special functions, which may be computed via the Padé expansion of the Fermi function. This results in a formalism which is ideally multiscale in time, i.e. which does not get more expensive with increasing number of time steps, and which can therefore be used to study the short-time transient and steady-state transport quantities with identical computational expense. Some numerical calculations of the current and noise response to the switch-on of a time-dependent bias are then performed.

The first kind of time-dependent driving considered in this thesis is periodic. Some preliminary calculations are performed on periodically-driven quantum dots, and the effect on the current of varying the driving frequency, temperature, lead-molecule coupling and driving amplitude is studied. Next, the problem of quantum pumping is considered, and sufficient conditions are found for a periodically driven system with zero time-average bias to generate a net time-averaged current through the system. The effects of finite size on the current response to static and periodic biases are investigated, again using the molecular wire as an illustrative model. Next, calculations of the quantum pump current are presented for a particular biharmonic bias model, and in particular the effect on this current of breaking the sinusoidal shape of the driving field. Finally, the discussion turns to calculations of the cross-lead current correlations in extended systems in response to static and periodic biases. By investigating molecular wires of different lengths and internal hopping parameters, a signature of the traversal time for electrons crossing the sample is found in both the transient and steady-state cross-lead current correlations.

As there are no restrictions on the nature of the time-dependent bias driving the system out of equilibrium, one can use this formalism to study the electronic response to a classically fluctuating bias in the leads. The second kind of time-dependent driving studied in this thesis is therefore non-deterministic, and exact formulas for the bias-averaged current response to a stochastic bias are derived for the first time. This problem is formally analogous to the use of the Langevin equation approach to obtain a relation between the conductance in a classical circuit and the strength of fluctuations in an external driving bias: the so-called Nyquist theorem. An exact quantum version of the Nyquist theorem is derived for a driving bias with colour noise which relates the strength of fluctuations, the correlation time of fluctuations, the temperature and conductance in a molecular junction. Due to the nonlinear relation between current and driving bias in these junctions, it is not always true that the conductance will decrease with increasing fluctuation strength. Instead, there can be particular intermediate values of the fluctuation strength at which peaks in the conductance are observed, in a stochastic resonance effect.

Mechanical alloying has been widely utilized to break down the clustered CNTs for incorporation in the metal matrix composites. However, the breakage of CNTs during the ball milling process degrades their effectiveness. Due to the challenges in collecting the CNTs for measurement, quantitative study of CNT breakage has been difficult. In this study, the CNTs with Al6061 powder were mechanically alloyed with high energy milling equipment. The CNTs from the surface of mechanically alloyed particles were collected and measured. Due to the difficulty in obtaining the CNTs embedded inside the particles, a mathematical model has been developed to predict the overall CNT length distribution in the composite. Significant CNT breakage occurred during the initial phase of the mechanical alloying due to the crushing of the clusters. The model predicted that no further change occurred in the overall CNT length during time greater than 1 h of mechanical alloying because most of the CNTs had already become embedded within the particles and were thus protected from further milling media impacts. A faster dispersion of CNTs and lower particle fracturing rate may help preserve the original CNTs.

The present study was aimed at improving the mechanical performance of epoxy based structural joints in aerospace, automotive, construction and marine industries. Epoxy adhesives have many applications in various industries, due to their exceptional material properties like flexibility, low maintenance, uniform stress distribution, durability and cost effectiveness. Single lap joints were prepared from Aluminum 2014-T3 and Magnolia 6380 epoxy adhesive. These single lap joints were tested according to specifications of ASTM-D1002 to evaluate the mechanical performance mainly shear strength of epoxy adhesive. The surface preparation procedures were carried out to enhance the adhesion between epoxy and aluminum test specimens. Graphene nano-flakes were added into the epoxy at 0, 0.5, 1, 2, and 3 weight percentages (wt%), to improve the load carrying capacity and efficiency of adhesive joints. Three test specimens of single lap joints were prepared for each sample and shear tests were conducted using MTS-Tensile machine to evaluate shear strength of an adhesive joint. It was observed that the load bearing capacity and shear strength of the adhesive joints were improved due to the inclusion of graphene nano-flakes into the epoxy. The major improvements were observed at 0.5wt% and 1wt% graphene inclusions by 1.37% and 10.43% increase in shear strength, when compared with baseline test coupons.

We present a combined experimental and theoretical quantification of the adsorption enthalpies of seven organic molecules (acetone, acetonitrile, dichloromethane, ethanol, ethyl acetate, hexane, and toluene) on graphene. Adsorption enthalpies were measured by inverse gas chromatography and ranged from −5.9 kcal/mol for dichloromethane to −13.5 kcal/mol for toluene. The strength of interaction between graphene and the organic molecules was estimated by density functional theory (PBE, B97D, M06-2X, and optB88-vdW), wave function theory (MP2, SCS(MI)-MP2, MP2.5, MP2.X, and CCSD(T)), and empirical calculations (OPLS-AA) using two graphene models: coronene and infinite graphene. Symmetry-adapted perturbation theory calculations indicated that the interactions were governed by London dispersive forces (amounting to ∼60% of attractive interactions), even for the polar molecules. The results also showed that the adsorption enthalpies were largely controlled by the interaction energy. Adsorption enthalpies obtained from ab initio molecular dynamics employing non-local optB88-vdW functional were in excellent agreement with the experimental data, indicating that the functional can cover physical phenomena behind adsorption of organic molecules on graphene sufficiently well.

MXenes are the emerging class of 2D materials, widely explored as supercapacitor electrodes with their explicit properties. Using the pseudocapacitive nature of the widely reported MXene-Ti 3 C 2 T x, an asymmetric cell is designed with Ti 3 C 2 T x as the negative electrode and Vanadium nitride/Porous carbon as the positive electrode. The asymmetric cell provides a high cell voltage of 1.8 V with a specific capacitance of 105 F/g at 1 A/g in 6 M KOH. It also presents a capacitance retention of 73% even after 10,000 charge-discharge cycles. The asymmetric cell exhibits a high potential window, which is about 3 times higher when compared to symmetric supercapacitors. The asymmetric electrode system exhibits an energy density of 12.81 Wh/kg and a corresponding power density of 985.8 W/kg at 1 A/g. This value of energy density is greater when compared to various symmetric supercapacitors. Thus Ti 3 C 2 T x MXene electrodes can effectively replace the conventional carbon electrodes used...

In this work, graphene was used as a filler for banyan aerial root fibers
reinforced epoxy composites at various compositions. The synergetic effect of graphene and banyan fibers, on the physical and mechanical characteristics of the epoxy thermoset, was studied. The mechanical tests, hardness, water absorption behavior and morphology of the composites were studied. Significant improvement in tensile strength, flexural strength, shore D hardness and substantial reduction in the percentage of water absorption was observed. This paper also discusses the ideal proportion of banyan fibers with graphene powder for the development of the improved epoxy composites. The optimum concentration of the composites was observed at 4% of graphene powder in the 40% banyan fiber-reinforced hybrid epoxy composites. From the results, it is proved that graphene combined with 40% banyan fiber-reinforced epoxy hybrid composites will efficiently improve the strength of the composites.

Since chemical vapor deposition of carbon-containing precursors onto transition metals tends to develop as the preferred growth process for the mass production of graphene films, the deep understanding of its mechanism becomes mandatory. In the case of nickel, which represents an economically viable catalytic substrate, the solubility of carbon is significant enough so that the growth mechanism proceeds in at least two steps: the dissolution of carbon in the metal followed by the precipitation of graphene at the surface. In this work, we use ion implantation to dissolve calibrated amounts of carbon in nickel thin films and grow graphene films by annealing. Observations of those graphene films using transmission electron microscopy , directly on the growth substrate as well as transfered on TEM grids, allowed us to precisely study the mechanisms that lead to their formation.

Contact engineering, especially at the interface between metal and 2D semiconductors, to enable high‐performance devices remains a formidable challenge due to the inevitable chemical disorder and Fermi‐level pinning at the interface. Here, the authors report the InSe–Se vertical van der Waals (vdW) heterostructures to achieve high field‐effect mobility and electrical stability in 30 nm InSe field‐effect transistor (FET), which has a low lattice mismatch of 1.1% and form 2D/2D low‐resistance contacts, creating an InSe contact interface that substantially limits chemical disorder and Fermi‐level pinning. The Se layer forms a vdW contact to prevent the damage induced by direct metallization and acts as a tunneling layer as well as a protective encapsulation layer. Using this approach, heterojunction devices with a high field‐effect mobility of ≈2500 cm2 (V s)−1 and an excellent on‐state current of ≈10−3 A at room temperature is achieved. Furthermore, the device field‐effect mobility degrades by only 3.46% following two months of storage time in open air, which represents the best electrical stability reported to date. In particular, the heterojunction devices exhibit a better photoresponsivity compared with InSe devices in practical application. This study provides a highly valuable strategy to improve the contact condition of metal/2D semiconductors for high‐performance, 2D‐based electronics and optoelectronics.

Motivated by the success and exhaustive research on carbon nanotubes (CNTs) based drug delivery, graphene, a two-dimensional; honeycomb crystal lattice has emerged as the rising star in recent years. Graphene is a flat monolayer of carbon atoms that holds many promising properties such as unparalleled thermal conductivity, remarkable electronic properties, and most intriguingly higher planar surface and superlative mechanical strength, which are attractive in biotechnological applications. Delivery of anti-cancer drugs using graphene and its derivatives has sparked major interest in this emerging field. The anti-cancer therapies often pose a limitation of insolubility, administration problems and cell-penetration ability. In addition, systemic toxicity caused by lack of selective targeting towards cancer cells and inefficient distribution limits its clinical applications. Graphene nanocomposite is a promising tool to address these drawbacks. This review will focus on various synthesis and functionalization of graphene and graphene oxide for providing better solubil-ity and targeted drug delivery at cancer cells. A more advanced and 'smart' graphene hybrid nanostructures that have several functionalities such as stimulus-response mediated delivery, imaging at release sites as well as transfection into cancer cells are also presented. A brief description on the challenges and perspectives for future research in this field is also discussed.

We present results of molecular dynamics simulations of
graphene on Cu surfaces. Interactions were modelled with the
charge-optimized many-body potential, which gives a
reasonable though not flawless description of the graphene–Cu
system. The interaction between Cu and complete graphene
sheets is characterized by an ‘averaged out’ interaction at a large bonding distance. Many bonding characteristics are indifferent to the details of how the Cu surface atoms are arranged, including the surface orientation and even if the
surface is solid or molten. Graphene edges have a strong interaction with the Cu substrates. Systems were modelled at various temperatures, ranging from 0 K to the Cu melting
temperature. At high temperature we find that the presence of graphene slightly stabilizes the Cu surface and retards surface melting. After cooling down to room temperature, the Cu substrate is 1.7% smaller than the graphene due to difference thermal expansion coefficients. This leads to the formation of wrinkles in graphene. Single wrinkles experience only small migration barriers and are quite mobile. When multiple wrinkles intersect, they form immobile knots that hinder further movement of the connected wrinkles. The elastic energy of the wrinkles and knots due to bending of the graphene is determined.

Graphene has emerged as the most popular topic in the active research field since graphene's discovery in 2004 by Andrei Geim and Kostya Novoselov. Since then, graphene research has exponentially accelerated because of its extraordinary properties, which have attracted the interest of researchers all over the world. For example, among the key properties are its thermal conductivity, electrical conductivity, optical transparency, and mechanical properties. These remarkable properties of graphene show its promise for applications in different industries including optical electronics, photovoltaic systems and others. However, the large-scale production and transfer method onto target substrates of monolayer graphene for commercial and industrial applications are still under study in the improvement stage. Therefore, this review presents the state-of-the-art research activities and latest advancement in the synthesis of graphene using various carbon precursors including solid, liquid and gas carbon feedstocks. The characterization methods have also been critically discussed in this review. In addition, the advancement in the transfer methods onto target substrates for achieving clean and high-quality transferred graphene have been thoroughly reviewed. Furthermore, the current growth mechanisms of single and multilayer graphene have also been discussed.

This chapter focuses on the nanocomposite of an important type of thermoplastic - polyvinyl chloride (PVC). Carbon nanomaterials have gained significant research interest as polymer reinforcement. PVC/nanocarbon nanocomposites possess excellent electrical conductivity, thermal stability, glass transition temperature, strength, toughness, modulus, and other physical properties. Dispersal of nanocarbons in a matrix is crucial to attaining high performance materials. Among the various nanocarbons, graphene and graphene oxide nanofillers have fine dispersion in the matrix. Various techniques have been used to forming the uniformly dispersed polyvinyl chloride-based nanocomposite. Moreover, the molecular level interactions between the PVC matrix and graphene may improve the nanocomposite performance. The polyvinyl chloride/graphene nanocomposite have found potential in solar cell, fuel cell, supercapacitor, sensor, batteries, microelectronics, electromagnetic shielding, and aerospace fields. Applications of these materials are continuously increasing due to the light weight, tunable features, and straightforward processing techniques. Another aim of this article is to reveal the obscured properties of the PVC-based nanocomposite for the future advance technical applications.

Graphene features an array of extraordinary mechanical, physical and electrical properties, and it is of great interest to impart such properties to polymeric materials by use of graphene and its derivatives as filler materials. The focus of this comprehensive review is on the preparation of graphene-based polymeric nanocomposite materials by use of synthetic approaches involving aqueous emulsions of polymer (nano)particles. These techniques can be broadly categorized as in situ polymerization (where the monomer(s) is/are polymerized in the presence of the composite phase) and solution blending, where an aqueous dispersion of polymer particles is prepared separately and subsequently mixed with an aqueous dispersion of graphene-based material. Many of these techniques involve the use of derivatives of graphene such as graphene oxide and “reduced” graphene oxide. The fundamental challenge is that graphene as well as graphene oxide have low compatibility with most synthetic polymers, and it is consequently difficult to prepare homogeneous polymer nanocomposites without aggregation and restacking. One of the important features of graphene oxide is that it can act as a surfactant in oil-water emulsions, which has been exploited extensively for preparation of a range of composite particles/materials. Polymer/graphene nanocomposite synthesis via emulsion-based approaches is an active field of research with plenty of opportunities for significant future advancement with a range of potential applications.

Multifunctional cotton fabric with high electrical conductivity and ultrastrong UV radiation protection
properties was successfully fabricated by coating graphene oxide (GO) nanosheet dispersion on fabric
surface via vacuum
filtration deposition (VFD) method, and then the treated fabric was assembled with
polyaniline (PANI) by in-situ chemical polymerization process. The structure and morphological studies
showed that the deposition of GO nanosheet is benefit to enhance the uniformity of aniline
polymerization on the surface of PANI-GO-cotton fabric. Furthermore, the electrical resistivity of PANI-
GO-cotton decrease approximately 106 times compared with control cotton, reached at 48.35 V cm.
PANI-GO-cotton also performed ultrastrong UV radiation protection ability with a UPF value of 445.21,
which is superhigher than that of control fabric (UPF rating at 6.86). Moreover, even repeated 10 times
water laundering showed nearly no effect on electrical conductivity and UV radiation protection
efficiency.