Newsflash

The drive for lightweight materials to reduce overall cost and environmental impact for automotive manufacturers is nothing new.  Fuel economy attracts car buyers too. That is how majority of steel parts have been replaced in F-150 pickup truck by aluminum parts, reducing overall weight over 500 pounds. Then there are alloys, carbon fiber and plastics composites.The ambition for lighter vehicles did not stop with alloys (magnesium, aluminum), and/or composites (glass, carbon fibers).  Recently, Japanese researchers at Kyoto University led by Professor Hiroaki Yano along with its industrial partners (Denso Corporation and Daikyo-Nishikawa Corporation) reported that they were developing cellulose nanofiber based materials for automotive as well as aircraft parts to reduce environmental footprint while increasing product performance.Inevitable questions are: 1) would these materials be cost effective? 2) What would be the service life of these products compared to the current ones? 3) How about the parts’ safety in situations like crash or fire?A final question that an automaker has to ask is: what would be the pay back time to replace current production line (machinery) to CNF based plastics line?Reference: https://www.japantimes.co.jp/news/2017/08/15/business/researchers-japan-use-wood-make-cellulose-nanofiber-auto-parts-stronger-lighter-metal/#.WbAIKeTXuUm...
We know polycarbonates mostly from its use in plastics water bottles, safety goggles, smart phones, structural panels (glazing) and the list goes on.  A quick look at Wikipedia gives a spectrum of applications.However, polycarbonates have its weaknesses along with the BPA (bis-phenol) controversy. Polymers such as polysulfates and polysulfonates have similar if not better mechanical properties than polycarbonates.  The issue has been how reliably scale-up the manufacturing process of polysulfates and polysulfonates?“Click chemistry” is a concept in organic chemistry by which highly reactive reactions provide high yielding products and require little to no purification.  The concept was introduced by Nobel Prize winner Professor K. Barry Sharpless in 2001.A recent work published in Nature Chemistry, by a team of researchers from The Scripps Research Institute (La Jolla), Lawrence Berkley National Laboratory (Berkley), California and Shanghai Institute of Organic Chemistry & Soochow University, China claimed that reduced cost of catalyst, product purity, and by-product recycling make their work ready to move from laboratory research to industrial process.Chemists are at work indeed!References:https://en.wikipedia.org/wiki/PolycarbonateK. Barry Sharpless et al; Nature Chemistry, 2017 DOI: 10.1038/nchem.2796...
In a recent The Atlantic interview Bill Gates made a wish on an energy miracle, “Here’s a source of energy that is cheaper than your coal plants, and by the way, from a global-pollution and local-pollution point of view, it’s also better”.  The race is on to find that source. One such energy source is solar energy. We all know that solar energy can be harnessed to generate thermal energy or electrical energy for use in the residential and/or in the commercial applications.  Any material that can store Solar Thermal Energy is called Solar Thermal Fuel (STF).  The quest to harvest solar energy, store the same and use it when needed has been the focus of research in industry and academia alike. For the first time, Professor Grossman’s team at MIT, Cambridge (USA) has come up with a new approach which uses polymer Solar Thermal Fuel (STF) storage platform utilizing STF in its solid-state.  According to the published article, researchers stated, “Closed cycle systems offer an opportunity for solar energy harvesting and storage all within the same material. This approach enables uniform films capable of appreciable heat storage of up to 30 Wh kg?1 and that can withstand temperature of up to 180 °C.”How the STF process works?Certain molecules (chemicals) can have 2 different stable structural forms. These structures are called conformations.  When original molecular conformation is exposed to sunlight, the molecule gets charged and the original conformation changes to the other and stay in that charged conformation for a long period.  The charged molecule snaps back to their original shape (conformation), when triggered by a very specific temperature or other stimulus generating heat in the process. Currently, developed polymeric film can release heat about 10 degree C above the surrounding temperature. Film property improvements are underway. German auto company BMW, has sponsored this research. Where the potential application lies - your guess is as good as mine.References:The Atlantic, p 56, November 2015Zhitomirsky, D., Cho, E. and Grossman, J. C. (2015), Solid-State Solar Thermal Fuels for Heat Release Applications. Adv. Energy Mater., 1502006. doi:10.1002/aenm.201502006...
In a recent The Atlantic interview Bill Gates made a wish on an energy miracle, “Here’s a source of energy that is cheaper than your coal plants, and by the way, from a global-pollution and local-pollution point of view, it’s also better”.  The race is on to find that source. One such energy source is solar energy. We all know that solar energy can be harnessed to generate thermal energy or electrical energy for use in the residential and/or in the commercial applications.  Any material that can store Solar Thermal Energy is called Solar Thermal Fuel (STF).  The quest to harvest solar energy, store the same and use it when needed has been the focus of research in industry and academia alike. For the first time, Professor Grossman’s team at MIT, Cambridge (USA) has come up with a new approach which uses polymer Solar Thermal Fuel (STF) storage platform utilizing STF in its solid-state.  According to the published article, researchers stated, “Closed cycle systems offer an opportunity for solar energy harvesting and storage all within the same material. This approach enables uniform films capable of appreciable heat storage of up to 30 Wh kg?1 and that can withstand temperature of up to 180 °C.”How the STF process works?Certain molecules (chemicals) can have 2 different stable structural forms. These structures are called conformations.  When original molecular conformation is exposed to sunlight, the molecule gets charged and the original conformation changes to the other and stay in that charged conformation for a long period.  The charged molecule snaps back to their original shape (conformation), when triggered by a very specific temperature or other stimulus generating heat in the process. Currently, developed polymeric film can release heat about 10 degree C above the surrounding temperature. Film property improvements are underway. German auto company BMW, has sponsored this research. Where the potential application lies - your guess is as good as mine.References:The Atlantic, p 56, November 2015Zhitomirsky, D., Cho, E. and Grossman, J. C. (2015), Solid-State Solar Thermal Fuels for Heat Release Applications. Adv. Energy Mater., 1502006. doi:10.1002/aenm.201502006...
Reliable and high performance lithium ion batteries commonly known as LIBS are highly sought after product by industries. We all have heard stories about laptops, electric vehicles, airplanes catching fires due to LIBS. Underlying problem is the battery overheating. Preventing batteries from overheating is crucial to the public safety.  Now a team of researchers at Stanford University designed a thermo-responsive (heat sensitive) plastic composite film made from polyethylene and spiky nickel microparticles coated with graphene which shuts down the battery if the temperature is too high.         In a recently published work led by Yi Cui and Zhenan Bao of Stanford University, USA concluded “Safe batteries with this thermoresponsive polymer switching (TRPS) materials show excellent battery performance at normal temperature and shut down rapidly under abnormal conditions, such as overheating and shorting.” How practical this design approach is? Time will tell.References: Y. Cui, Z. Bao et al Nature Energy vol.1, Article number: 15009 (2016); DOI: 10.1038/nenergy.2015.9Chemical & Engineering News, Page 7, January 18, 2016...
In aviation industry, the focus is how to improve fuel safety and handling. Mike Jaffe and Sahitya Allam gave their perspective on safer fuels by integrating polymer theory into design (Science, 350, No. 6256, p. 32, 2015).Mist (generated from the fuel) is much more flammable than the liquid and that is why anti-misting kerosene interferes with mist formation when a low percentage of a polymer is added into it.  The problem however, is that the polymer chain undergoes scission during handling and can’t assist in suppressing mist formation. The answer comes from a recent paper published in the Journal Science by Professor Julia Kornfield and her cross-functional team at Caltech, Pasadena, USA. The group designed a megasupramolecules having polycyclooctadiene backbones and acid or amine end groups (telechelic polymer) which is short enough to resist hydrodynamic chain scission while protecting covalent bonds through reversible linkages. Yes, polymers can be designed to suit our societal needs including aviation fuel safety.Reference: M-H Wei, B. Li, R.L. Ameri David, S.C. Jones, V. Sarohia, J.A. Schmitigal and J.A. Kornfield; Science, 350, (6256), pp. 72-75 (2015)...
At the TED conference, Carbon3D, a Vancouver based company touted a radical 3D printing technology and named it CLIP or Continuous Liquid Interface Product. CLIP grows parts instead of printing them layer by layer. It harnesses light and oxygen to continuously grow objects from a pool of resin.  The result: make commercial quality parts at game-changing speed.  CLIP is 25 to 100 times faster than traditional 3D printing technique.  To make the point, Carbon3D web site provides a head-to-head comparison of CLIP to Polyjet, SLS and SLA.[Press release: March 16, 2015, Vancouver, Canada.  www.carbon3D.com]...
Self-healing plastics has been around for a while. Applications include self-healing medical implants, self-repairing materials for use in airplanes and spacecrafts. Even scientists have made polymeric materials that can repair itself multiple times. A recent report in Science describes a significant advance in self-healing plastics. The authors describe a product that mimics how blood can clot to heal a wound. When the plastic is damaged a pair of pre-polymers in channels combines and rapidly forms a gel, which then hardens over 3 hours.The authors demonstrated that holes up to 8 millimeters wide can be repaired. The repaired parts can absorb 62% of the total energy absorbed by undamaged parts.  Science never stops.Reference:S. R. White, J. S. Moore, N. R. Sottos, B. P. Krull, W. A. Santa Cruz, R. C. R. Gergely; Science, Restoration of Large Damage Volumes in Polymers, Vol. 344 no. 6184 pp. 620-623; (9 May 2014). ...
Knowingly or unknowingly, flexible electronics has become a part of our daily life.  Transparent conductive films (TCFs) are used in mobile phones, tablets, laptops and displays.  Currently, Indium Tin Oxide or commonly known as ITO is the material of choice.  But use of ITO has some major disadvantages and these are brittleness, higher conductivity at greater transparency, and supply of Indium.  This is where non-ITO materials come into play. Based in St. Paul, Minnesota (USA), Cima NaoTech’s uses its SANTETM nanoparticle technology, a silver nanoparticle conductive coating which self-assembles into a random mesh like network when coated onto a flexible substrate such as PET and PC.  According to a recent press release, the company stated SANTETM nanoparticle technology enabled transparent conductors in a multitude markets from large format multi-touch displays to capacitive sensors, transparent and mouldable EMI shielding, transparent heaters, antennas, OLED lighting, electrochromic and other flexible applications.  Cima NanoTech is working with Silicon Integrated Systems Corp. (SIS) of Taiwan and using its highly conductive SANTE FS200TM touch films to develop large format touch screens.References: Press release, San Diego, June 03, 2014; www.cimananotech.com ; http://www.cimananotech.com/sante-technology ; http://www.sis.com/...
In an article appeared today (January 29, 2014) in The Guardian newspaper, Stuart Dredge wrote, “From jet parts to unborn babies, icebergs to crime scenes, dolls to houses: how new technology is shaking up making things”1. Mr. Dredge was speaking about 3D printing technology.  The heart of this technology is the 3D printer itself. Stratasys, a company headquartered in Minneapolis, USA is the manufacturer of 3D printers.  It recently announced the launch of Color Multi-material 3D Printer, the first and only 3D printer to combine colors with multi-material 3D printing.  According to the press release2, by using cyan, magenta, and yellow, multi-material objects can be printed in hundreds of colors.  The technology is based on proven Connex technology.  While the base materials are plastics and elastomers, they can be combined and treated to make finished products of wide ranging flexibility and rigidity, transparency and opacity.  Designers, engineers and manufacturers can create models, mold, and parts that match the characteristics of the finished production part. This includes achieving excellent mechanical properties.  According to the manufacturer, print job in the newly revealed printer can run with about 30 kg of resin per cycle and prints as fine as 16 micron layers for models.  No wonder why some call the new Color Multi-material 3D printer a groundbreaking stuff.References: 1. www.theguardian.com.technology/2014/jan/29/3d-printing-limbs-cars-selfies (January 29, 2014)2. http://investors.stratasys.com/releasedetail.cfm?ReleaseID=821134 (August 3, 2014)...
Instead of stitches or skin staples, doctors use skin glue to close wounds. The glue joinsthe edges of a wound together while the wounds heal underneath. Most of the timeskin glue is used for simple cuts or wounds. According to the paper published inScience Translational Medicine, there are no clinically approved surgical glues thatare non-toxic, bind strongly to tissue, and work well in wet and highly dynamicenvironments within the body. This is the reason why this published work is promisingwhere infants born with heart defects would benefit tremendously. Researchers at the Brigham and Women’s hospital in Boston have engineered ‘bio-inspired’ gluethat can bind strongly to tissues on demand, and work well in the presence ofactively contracting tissues and blood flow. The authors of the paper show howthe glue can effectively be used to repair defects of the heart and blood vessels during minimally invasive procedures. [References: P. J. del Nido et al; Sci. Transl. Med., DOI: 10.1126/scitranslmed.3006557; See also, www.geckobiomedical.com/news/gecko-biomedicals-co-founde.html]...
Stability of organic electronics in water is a major research challenge. For this reason,organic electronics has yet to see any sensing application in aqueous environment.However, as understanding of underlying mechanism of stability aspect is becomingclearer, new developmental efforts to make water compatible organic polymer devicesare taking place. Recently, Professor Zhenan Bao’s group in the department of chemical engineering at Stanforduniversity revealed in a paper published in the journal of Nature Communications thatsolution- processable organic polymer could be stable under both in freshwater andin seawater. Developed organic field-effect transistor sensor is able to detect mercury ionsin the marine environment (high salt environment). Researchers believe that the work hasthe potential to develop inexpensive, ink-jet printed, and large-scale environmental monitoring devices. [References: O. Knopfmacher, M.L. Hammock, A.L. Appleton, G. Schwartz, J. Mei, T. Lei, J. Pei,and Z. Bao; Nature Communications, 5, 2954, January 6, 2014; DOI: 10.1038/ncomms3954]...
Insulin, the wonder medicine for diabetes was discovered about a century ago.Since insulin does not get into the blood stream easily, diabetes patients oftenhave injected themselves with insulin. Now a group of scientists led by Dr. Sanyog Jainat the Center for Pharmaceutical Nanotechnology of National Institute of Pharmaceutical Education and Research in Punjab, India has designed a polymerbased package for oral insulin administration. The package design addresses two major obstacles, 1) digestive enzymes must notdegrade insulin prior to its action and 2) the insulin gets into the blood stream.The package contained folic acid functionalized insulin loaded in liposomes.To protect the liposomes (lipids or fat molecules) they were alternately coated withnegatively charged polyacrylic acid (PAA), and positively charged poly allylamine hydrochloride. Studies were conducted to compare the efficacy of bothdelivery systems: designed polyelectrolyte based insulin and standard insulinsolution. Effects of oral administration lasted longer than that of injectedinsulin, authors reported in a recent article in Biomacromolecules. [Reference: A.K. Agarwal, H. Harde, K. Thanki, and S. Jain; Biomacrmolecules, Nov. 27, 2013;DOI: 10.1021/bm401580k]...
Research in the area of stretchable electronics is heating up!  Thanks to polymers. Led by Professor George M. Whitesides of Harvard University (USA), a team of researchers have demonstrated in a recently published paper in Science that ionic conductors can be used in devices requiring voltages and frequencies much higher than commonly associated with devices using ionic conductors.  The team showed for the first time that electrical charges carried by ions and not electrons, can be utilized in fast-moving, high voltage devices.As a proof of concept, the authors of the study built a transparent loudspeaker that produces sound across the full audible range i.e., 20 Hz to 20 kHz.  Components [such as VHB 4910 tape (acrylic tape with PE liner), polyacrylamide hydrogel containing NaCl electrolyte] used for the high speed, transparent actuators are described in the paper.Tissues and cells are soft and require stretchable conductors for biological systems. Many hydrogels are biocompatible which makes this work particularly an important one. The design of gel-based ionic conductors is highly stretchable, completely transparent and offer new opportunities for designers of soft machines.   [Reference: C.Keplinger, J-Y. Sun, C.C. Foo, P. Rothemund, G.M. Whitesides, and Z. Suo; Science, 341 (6149), pp. 984-987 (2013); DOI: 10.1126/science.1240228]...
Interweaving biological tissue with functional electronics, one can make bionic ears.  NASA has tested 3D-printed rocket engine part.  Then why not 3D print yourself?Well, Twinkind, a German start-up company is now offering enthusiasts statues of themselves for display.  How this works?  A full body scanner takes an image of the customer’s body, transfers the file to the printer after which 3D printer laser sinters a composite powder layer by layer into the customer image.Can we dare to say that Madame Tussauds wax figure of Voltaire can now be 3D printed in polymers soon!  [Reference: www.twinkind.com ]...
Polymer membranes have become a leading contender in numerous separation processes.  Be it in gas (air, hydrogen etc.) or be it in water purifications (salinated water, waste water etc.).  Not only polymer membrane technology helps reducing the environmental impact but also it is cost-effective.  Fracking in shell gas is one of many examples. New advances in drilling technology (such as horizontal drilling) have led to new hydraulic fractures called fracking.  Hydraulic fracturing requires about 2.5 to 5 million gallons of water per well.  Water management and its disposal are major costs for producers.One major challenge, however, of the membrane technology is the fouling (damage caused by contaminants) mitigation.  This has been recently studied by a group of researchers from University of Texas at Austin led by Professor Benny Freeman to address efficiency and reuse of water for fracking in shale gas plays.Researchers modified polydopamine coated UF (ultrafiltration) module by grafting polyethylene glycol brushes onto it.  The result is more hydrophilic surfaces which in turn improved cleaning efficiency relative to unmodified modules. The coating improves the membrane life, and can easily be applied to membrane surface by rinsing it through the recycling system.[References: D.J. Miller, X. Huang, H. Li, S. Kasemset, A. Lee, D. Agnihotri, T. Hayes, D.R. Paul, and B. Freeman; J. Membrane Sci., 437, pp. 265-275 (2013); Also see www.advancedhydro.net ]...
Flexible electronics can change the way we use electronic devices.  It is a term used for assembling electronic circuits by mounting electronic devices on a flexible plastic. A recent review article captured the advancement of CNT and graphene based flexible thin film transistors from material preparation, device fabrication to transistor performance control compared to traditional rigid silicon1. Silicon is used almost exclusively in electronic devices.Now Prof. Ali Javey led a team at the University of California, Berkley to develop a printing process to make nanotube transistors at room temperature with gravure printer.  The plastics used is polyethylene terephthalate (PET). The device exhibited excellent performance with mobility and on/off current ratio of up to ~9 cm2/ (V s) and 105 respectively.  Also, maximum bendability is observed.  The paper authors conclude that this high-throughput printing process serves as enabling nanomanufacturing scheme for range of large-area electronic applications based on nanotube networks2. References:1. D-M. Sun, C. Liu, W-C. Ren and H-M Cheng; Small, DOI: 10.1002/smll.2012031542. P.H. Lau, K. Takei, C. Wang, Y. Zu, J. Kim, Z. Yu, T. Takahashi, G. Cho, and Ali Javey; Nano Letters, 13 (8), pp. 3864-3869 (2013); DOI. 10.1021/nl401934a...
Drinking coffee from paper cups are as common as drinking water from plastics bottle. The issue however, is recycling of disposable cups. The disposable cups are made up of 90-95% of high strength paper (fibers) with a 5% thin coating of plastic (PE).To address the recycling issue, James Cropper Speciality Papers of UK have developed a process which involves softening the cup waste, and separating the plastic coating from the fiber.  After skimming off the plastic, remains are pulverised and recycled, leaving water and pulp behind.  According to the company news release, the high grade pulp is reused in luxury papers and packaging materials.An innovative approach to address a common problem.[Reference: www.jamescropper.com/news ]...
A search for an alternative to rigid silicon wafers gave birth to the area of flexible or bendable electronics. Research has been intense for the past few years in the area flexible electronics as it opens up multitude of new applications. Polymers play an important role to exciting field of flexible electronics.In a recent research report, a team of scientist led by Prof. Ali Javey of University of California, Berkeley (USA)  has shown for the first time user-interactive electronic skin or e-skin can conformally wrap irregular surfaces and spatially map and quantify various stimuli through a built-in active matrix OLED display.  Three electronic components namely thin film transistor (uniform carbon nanotube based), pressure sensor, and OLED arrays (red, green, and blue) are integrated over a plastic substrate.  Spin coated and cured polyimide on a silicon wafer is used as the flexible substrate.  Details are in the paper.This work essentially provides a technology platform where integration of several components (organic and inorganic) can be done at a system level on plastic substrates. According to the paper, this e-skin technology could find applications in interactive input/control devices, smart wallpapers, robotics, and medical/health monitoring devices.    [Ref: C. Wang, D. Hwang, Z. Yu, K. Takei, J. Park, T. Chen, B. Ma, and Ali Javey; Nature Materials, Published online July 21, 2013; DOI: 10.1038/NMAT3711]...
Recent buzz in the technology world is 3D printing.  Researchers to designers are creating new products everyday using 3D printing technology.  Even eBay has unveiled its services to those looking to make their own creations using 3D printing App.Since ages composites have played a crucial role in our society. Inspired by natural (biological) composites such as bone or nacreous abalone shell, researchers from MIT (USA) and Stratasys have developed composite materials that have fracture behaviour similar to bones.  Using computer model with soft and stiff polymers, the team has come up with a specific topological arrangements (hierarchical structures) of polymer phases to boost the mechanical behaviour in the composites.Interestingly, the team has been able to manufacture (thanks to 3D printing) a composite material that is more than 20 times larger than its strongest constituent.  The referenced paper showed that one can use computer model to design composite materials of their choice, tailor the fracture pattern and then use 3D printing technology to manufacture the composites.[Ref: L.S. Dimas, G.H. Bratzel, I. Eylon, and M.J. Buehler; Advanced Functional Materials, Published online June 17, 2013; DOI: 10.1002/adfm.201300215]...

graphite figure_01         Here we go again. After intercalated compounds of graphite (1974), fullerenes (1985), and carbon nanotubes (1991), it is time for another allotrope of elemental carbon to be at the forefront of scientific curiosity (Boehm 2010). The allotrope is: “graphene”. By graphene, we mean the basal plane of graphite, a one atom thick two dimensional honeycomb layer of sp2 bonded carbon. Conversely, when many graphene layers are stacked regularly in three dimensions, graphite is created.

 

In the introductory chapter of the book, Graphite, Graphene, and Their Polymer Nanocomposites; editors have laid out their vision for this nascent and exciting area of research. They have also briefly described the contents of the each of the chapters and explained the logic that binds them into a compelling book. This allows the readers to derive the maximum benefit from the developing story of the most sought after carbonaceous nanomaterial, graphene. Clearly, there are a very large number of both challenges and opportunities in the area of graphene research. Plasticstrends is pleased to provide to its readers a revealing look at the contents of this book. 

 

 

 

Why such an interest in graphene? It’s all about the digital world, and the search for materials which will make integrated circuits smaller, faster and cheaper! Graphene is a semiconductor with a zero band gap and an exceptionally-high charge mobility. In fact, electron mobilities in graphene could reach values that are more than an order of magnitude higher than those encountered in a Si transistor. This opens up the tantalizing possibility that one day graphene might replace silicon as the building block of the electronic industry and revolutionize nanoelectronics. Although the existence of graphene
had been known for a long time, the material had never been actually synthesized. This had to await the work of Andre K. Geim and Konstantin S. Novoselov of the University of Manchester, UK who were awarded the 2010 Nobel Prize in Physics for their ability to isolate a defect free, single sheet of carbon atoms through micromechanical cleavage of graphite whereby monolayers are peeled from graphite crystals (Novoselov 2004). This method, however, produces a very small amount of pristine graphene which makes it unsuitable for efficient and scalable high volume manufacturing. Nevertheless, this pioneering work paved the way to the rise of intense graphene research. Important characteristics of graphene are that it is nano-scale in dimension, and it is derived from graphite, an inexpensive precursor. Consequently, a key goal of world-wide research has been to produce a large enough volume of pristine graphene safely and in a cost efficient manner. Other researchers are seeking practical
applications of graphene that will benefit society, especially in the electronics area.

 

In the technical literature, a number of methods have been described for producing graphene. These can broadly be classified as 1) micro-mechanical exfoliation, 2) epitaxial growth of graphene films, 3) chemical vapor deposition, 4) Unzipping of carbon nanotubes, and 5) reduction of graphene oxides. Each method has its own benefits and related drawbacks. A “bottom-up” approach using chemical synthesis is an interesting strategy (Choucair 2009, Cai 2010). However, scaling-up to produce large quantities remains a formidable challenge. Research efforts have, so far, established that an easier route to
manufacture large amounts of graphene is via the chemical exfoliation strategy. During chemical exfoliation, such as oxidation and subsequent reduction of graphite oxides, one produces partially or highly reduced graphene oxides. From a chemical viewpoint, these graphene sheets contain various types of residual oxygen-containing species. From a physical viewpoint, graphene sheets become
corrugated, and the graphene platelets can contain a variety of defects such as topological, adatoms, edges/cracks, vacancies, loops, adsorbed impurities and so on within the graphene-like structures (Terrones 2010). When the dimensions of these platelets fall in the nano-scale range, they are commonly termed “graphene nano-platelets” (GNPs). One of the most technologically promising
applications of nano-graphene materials is in polymer reinforcement. Studies have shown that stress transfer takes place from the polymer matrix to mono-layer graphene, indicating that graphene acts as a reinforcing phase (Gong 2010).

 

Polymers have been combined with other polymers to form blends and copolymers, mixed with talc, calcium carbonates and clays to give filled systems and extruded and molded with fibers and other anisotropic reinforcements to yield composites and hybrid materials. This simple “mix and match” approach has allowed the polymer scientists and engineers to utilize a small library of polymers to produce a bewildering array of useful products capable of possessing extremes of property values. Traditional filled-polymer composites typically utilize high loadings of micron sized filler particles to obtain desired properties. If the filler particle size is reduced to its nano-scale dimension from its micron size, similar properties are achieved but with a drastically reduced filler loading level to achieve percolation.
Primarily, this is due to the surface area to volume ratio of the nanoparticles which is several orders of magnitude larger than that of micron-sized fillers. To qualify to be called a “nanoparticle”, the particle has to have at least one dimension in the nanometer range. Therefore, when nanometer particles are dispersed in a polymer matrix the result is termed as “Polymer nanocomposite” (PNC); the matrix itself can be single or multiphase. The critical reinforcing effects of nanosized particles come from its aspect ratio, very large specific surface area, and the particle-matrix interactions. The original concepts for PNCs owe their origin to the invention of polyamide-clay composites in the Toyota Research Corporation in 1985 (Okada 1988). At that time, the objective was to make plastics used in under-the-hood applications be heat resistant and lighter than metal. Since then, the list of nano-particles has grown and PNCs have seen numerous commercial applications ranging from auto parts to packaging to coatings (Ashton 2010).

 

The latest addition to this palette of nanomaterials is graphene. Graphene layers could be stacked, functionalized, and modified to provide numerous types of graphene-based nano-scale materials. Rolled-up graphene, known as carbon nanotubes (CNTs) also has some structural flexibility. However, the performance and cost advantages of graphene challenge CNTs in nanocomposites, coatings, sensors, and energy storage device applications. For instance, the quality of graphene’s crystal and band structures yields uniquely low noise levels, increasing the sensitivity of the sensors (Yang 2010). While incorporation of CNTs in large scale integrated electronic architectures is a daunting task, graphene is highly amenable to microfabrication (de Heer 2007).  On the other hand, the cost advantage of graphene, graphene oxides or its nanoplatelets over CNTs stems from easy access to the graphitic precursor material, the cost, and the scalable method. In addition, due to its structure, graphene raises fewer toxicity issues as compared to carbon nanotubes.

 

This book attempts to compile, unify and present the emerging research trends in graphene-based polymer nanocomposites (GPNC). Researchers from several disciplines across the continents share their expertise and research knowledge about graphene, its properties, and the behavior of graphene-based composites. To the best of our knowledge, there is no other published monograph that provides this kind of a comprehensive snapshot of graphite, graphene, and their polymer nanocomposites. Without a broad perspective of the underlying physics and the chemistry of graphene, the full story of GPNC
remains untold. That is indeed our premise, and this is where the story begins.

 

Organization of the chapters

 

In chapter 1, John Zondlo from West Virginia University (USA) introduces us to natural and synthetic graphite, their properties and characterization techniques; graphite, after all, is the precursor to graphene.
The chapter lucidly describes where natural graphite is found and how synthetic graphite is manufactured. The author lists the prominent commercial applications of graphite in this chapter.

 

graphite figure 1 graphite figure 2

A graphite replacement heart valve (left), and graphite piston for a high-performance racing
engine (right). (Reproduced with permission from CRC Press)

 

It is evident that societal growth would be impeded without the use of graphite. Applications range from graphite electrodes in the electric arc furnace to graphite refractories in the steel and aluminum industries to nuclear reactors as both a moderator and a reflector.

 


graphite figure 3

Prismatic graphite structures in the core of a high-temperature nuclear reactor. (Reproduced with
permission from CRC Press)

 

 

A description of the importance of the different forms of graphite provides the link to the next few chapters.

 

Chapters 2 and 3 prepare us about graphene and its unique characteristics. Pierre Carmier of CEA-INAC / Université Joseph Fourier, Grenoble (France) elaborates in chapter 2 as to what has made graphene to climb to the top of the materials research chart. The author enumerates the electronic transport properties of graphene and explains how graphene's bipartite Bravais lattice and its gapless band structure make graphene so exotic! While delving into the theoretical issues of graphene, the author reminds us about the obstacles that have to be overcome for real carbon-based electronics. Most of us will agree that characterization of graphene is one of the most critical tasks in graphene research. Once graphene is synthesized, there are numerous techniques for its characterization. However, some of these are still evolving as technology advances. In chapter 3, Viera Skakalova and Dong Su of Max-Planck Institute, Stuttgart (Germany) and Alan B. Kaiser of Victoria University of Wellington (New Zealand) address this critical task. Not only do the authors summarize different characterization techniques available in microscopy (AFM, SEM, TEM, STM), and in spectroscopy (Raman, Augur, ARUPS, XPS) but they also discuss unique features of electrical conduction properties depending on the degree and the nature of defects in graphene.

 

graphite figure 4

 

SEM image of a CVD-grown graphene sheet on a nickel-coated SiO2/Si substrate (a) for 30
seconds and (b) for 7 minutes, and (c) Raman spectra of a CVD-grown graphene sheet on a
nickel-coated SiO2/Si obtained from different positions on the sample (scale bar: 1?m). (From
Park, H.J. et al., Carbon, 48, 1088-94, 2010. With permission)

 

The authors conclude this chapter by highlighting thermal conduction properties of graphene and how the thermoelectric power of graphene could aid in thermoelectric conversion of heat to electrical energy.

 

In the “top-down” approach, exfoliation of graphite is the key to the preparation of single or multiple graphene nanosheets. The quality of graphene materials can vary depending on the preparative methods. In reality, only cost-effective approaches to produce graphene sheets in large quantities would have commercial importance. In chapter 4, Martin Matis, Urszula Kosidlo, Friedemann Tonner, Carsten Glanz, and Ivica Kolaric of Fraunhofer Institute for Manufacturing Engineering and Automation, Stuttgart (Germany) detail electrochemical exfoliation of graphite and recent advances in the process. In addition to low cost, this exfoliation process has the advantage of producing functionalized graphene nano-platelets (GNP) in bulk quantities which is crucial to graphene-based nanocomposites manufacturing. In chapter 5, Weifeng Zhao and Guohua Chen of Huaqiao University (China) discuss different exfoliation routes to producing graphene and graphite nano-platelets for their use in polymer composites.

 

 

graphite figure 5

 

Dispersion properties of electrochemically derived graphite oxides before and after organic
modification with CTAB. Reproduced from H.W. Hu, G. Chen et al. Synthetic Met. 2009,
59:1505-1507.

 

Numerous studies on polymer based graphene nanocomposites are discussed. Ways to bring graphene nanomaterials into the real world of polymer processing were critically examined. The chapter authors propose the use of the wet ball-milling method to further exfoliate graphite nano-platelets into graphenes. Both chapters 4 and 5 describe possible routes to bringing graphene in bulk quantities to the market.

 

Chapters 6 through 9 showcase how graphene as the newest nano-materials can be used in numerous applications of commercial interest. Most of us will agree that clean energy is essential for securing the future of our planet. Chapter 6 deals with emerging clean energy applications of graphene-based materials in solar cells, lithium ion batteries, supercapacitors, and catalysis. Bin Luo, Minghui Liang, Michael Giersig, and Linjie Zhi of the National Center for Nanoscience and Technology, Beijing (China) discuss each of the clean energy applications in depth and provide a glimpse of graphene’s applications in the domain of clean energy technology.

 

 

graphite figure 5 a

 

Schematic illustration of the synthesis and structure of SnO2/GNS. (Reprinted with permission
from S.M. Paek, E. Yoo, et al. Nano Letters. 2009. 9(1): 72-75. Copyright 2009 American
Chemical Society)

 

These authors cite an impressive number of studies available in the current literature to capture the progress and future directions of each of these technologies. Because of its versatile application potential, the authors surmise that graphene could be used as a base material for various optoelectronic devices in the future. Martin Pumera of Nanyang Technological University (Singapore) delves into the electrochemistry of graphene-based nano-materials in chapter 7. It is known that chemical activity drastically changes at the edges of graphene depending on their carbon termination.  However, the author argues that there is no significant difference between the electrochemical response of single-, few-, and multi-layer graphene sheets. He discusses the importance of electrochemical performance of graphene
nano-structures in applications such as sensing and bio-sensing, supercapacitors and batteries.

 

Chapter 8 examines the fabrication of graphene-polymer nanocomposites and their applications as saturable absorbers for pulse lasers. Both graphene-based Q-switched lasers and mode-locked laser are examined. In this chapter, Kian Ping Loh, Qiaoliang Bao, Dingyan Tang, and Han Zhang of Nanyang Technological University (Singapore) show that the functionalization of graphene via covalent linking of a dye to the basal plane, and non-covalent attachment of aromatic molecules, aids in tuning the optical properties. The authors believe that electrospun graphene-polymer nanocomposites are promising candidates for practical and efficient photonic materials in the generation of high energy or ultrashort pulses.

 

graphite figure 6

Schematic illustration of the fabrication of graphene-polymer nanofiber composite by
electrospinning. (From Bao, Q. et al., Adv. Funct. Mater., 20, 782-791, 2010. With permission.) 

 

Epoxies are a class of thermoset polymers utilized extensively in products ranging from floor coatings to aircraft fuselages. Chapter 9 written by Iti Srivastava, Mohammad A. Rafiee, Fazel Yavari, Javed Rafiee, and Nikhil Koratkar of Rensselaer Polytechnic Institute, New York (USA) discusses the potential of graphene as a nanofiller in epoxy-based composite materials technology. The practical relevance of the nanocomposites’ mechanical properties such as tensile strength, Young’s modulus, buckling resistance, and ductility to material properties including fracture toughness and fatigue resistance are examined. The authors demonstrate that the graphene content required to significantly boost the mechanical properties of epoxy systems is 1-2 orders of magnitude lower than with the use of other competing nanofillers such as carbon nanotubes, nano-clays as well as silica/aluminum/titania nano-particles. The process of making hierarchical graphene/epoxy/E-glass fiber composites and their properties is also discussed. Finally, the authors have summarized technical issues that require attention in order to realize the full potential of graphene-based epoxy nanocomposites.

 

Nanoparticles come in different shapes and sizes. Chapter 10 provides an overview of the various types of nanofillers (ranging from metallic nanoparticles to silicates to bio-source nanoparticles to CNTs and graphenes) and reviews issues related to their polymer nanocomposites. This chapter authored by Musa R. Kamal and Jorge Uribe-Calderon of McGill University, Montreal (Canada) discusses challenges during the preparation of polymer nanocomposites. Chapters 11 and 12 address two distinctly different methods of GPNC preparation. Instead of employing the conventional route to polymer nanocomposites preparation, such as solution or melt mixing, Chapter 11 reveals how a robust and yet a simple technique for controlled polymerization, namely Atom Transfer Radical Polymerization (ATRP), is utilized to produce graphene-based polymer nanocomposites. Chapter 11 written by Arun K. Nandi, Rama K. Layek, Sanjoy Samanta, and Dhruba P. Chatterjee of the Indian Institute
for the Cultivation of Science, Kolkata (India) discusses the work of these authors and suggests that the ATRP method has the potential to fine tuning various properties of graphene-based polymer nanocomposites. Chapter 12 deals with the synthesis of GPNCs in a biodegradable polymer matrix and utilizes a solution mixing procedure. In this chapter, Gui Lin and James E. Mark of the
University of Cincinnati (USA) and Isao Noda of The Procter & Gamble Company, Ohio (USA) report on the structure-mechanical properties relationships of PHBHx reinforced by expanded graphite, graphene oxide and reduced graphene oxide.

 

Chapters 13 through 15 are devoted to the specialized properties of graphene-based polymer nanocomposites.

 

In chapter 13, Olga Shepelev and Samuel Kenig of Shenkar College of Engineering & Design, Ramat Gan (Israel), explore the opportunities to modify graphene nanoplatelets via surface treatment.

 

 

graphite figure 7

 

SEM image of PP / GNP nanocomposites containing modified GNP with polyol/silica
combination. (Reproduced with permission from CRC Press)

 

The authors compounded treated graphene into a polypropylene matrix to prepare polymer nanocomposites and showed that the treatments improved nanocomposite properties. Chapter 14 deals with water vapour barrier properties of GPNCs. In this chapter, Mathew Thompson, Sushant Agarwal, Rakesh K. Gupta of West Virginia University (USA), and Prithu Mukhopadhyay of IPEX Technologies Inc., Verdun (Canada) describe the process of molecular diffusion through polymers and show that graphene based PNCs have similar barrier behavior to clay-based PNCs, but the loading level of graphene needed is much lower. However, the authors question if the permeability reduction in the nanocomposite is due to diminished diffusion coefficients or lowered solubility of the diffusing molecule! These results
make out a case for the development of an appropriate theory for diffusion through PNCs. Chapter 15, authored by J.S. van der wal of Composite Agency, Amsterdam (The Netherlands), addresses chemically driven expansion of polymers within a composite structure, another important issue for long term service life of a product. Using methanol as a diffusing molecule, the author shows how a small amount of functionalized graphene sheets enhances the interfacial robustness of an epoxy composite.

 

In chapter 16, a review of graphene/polymer nanocomposites is reproduced. Here, Hyunwoo Kim, Ahmed A. Abdala (The Petroleum Institute, Abu Dhabi, UAE), and Christopher W. Macosko of the University of Minnesota, Minneapolis (USA) provide a lucid perspective of graphene based polymer nanocomposites research. Chapter 17 is concerned with preparation, properties and limitations of highly filled graphite-polymer composites. Improved electrical conductivity of graphite is attractive for the preparation of bipolar plates for the proton exchange membrane (PEM) used in fuel cells. This chapter coauthored by Sadhan C. Jana and Ling Du of University of Akron, Ohio (USA) employed a synergistic combination of expanded graphite and electrically conductive carbon black in epoxies to examine both in-plane and through-plane electrical conductivity.

 

The Opportunities and the Challenges

 

Graphene research has caught the world’s attention. Start-upcompanies that supply graphene materials are emerging in different parts of the world, and nanomaterials providers are adding graphene into their
product portfolio. Market research entities are totaling graphene sales numbers and projecting encouraging future sales volumes. Even governments are allocating money for funding graphene research. From a commercial standpoint, this is indeed good news for graphene-based polymer nanocomposites. This new material is entering a crucial segment in its product lifecycle from innovation to applications. But challenges still need to be overcome in order to bring about synergy between graphene research and its myriad anticipated applications.

 

The chemistry part of graphene and its derivatives has, however, begun to unfold. Graphene sheets are individually very strong, but, in graphite, sheets slide past one another making the material soft as is the case with pencil lead. Likewise, the thermal conductivity of suspended graphene differs considerably from graphene grown via chemical vapor deposition (CVD). Although composed of identical atoms, only differently arranged, the material properties are drastically different. Can the basal surface of graphene be made reactive? A knowledge of the interactions at the liquid-graphene interfaces is crucial to the application of graphene in electrochemical energy storage systems. So is the understanding and control of hydrophobic interactions in the field of protein folding and self-assembly. Studies are being conducted to examine the controllable interaction of water with epitaxial graphene films of different thickness values (Zhou 2012). Indeed, graphene’s wetting transparency comes from its extreme thinness. How one can exploit the wetting response in the design of conducting, conformal, and impermeable surface coatings (Rafiee 2012)? Only future studies will tell! Curiosity will find one day what happens to graphene when it is subjected to high compression. These new pieces of information will allow researchers to continue to address fundamental questions that go to the very core of our understanding of chemical interactions in
materials while simultaneously opening the doors to innovative applications.

 

The synthesis and properties of graphene nanoplatelets, its oxides, and the control of type and quantity of oxygen containing species have been the research foci of the graphene-based nanocomposites community (Terrones 2011, Mukhopadhyay 2011, Potts 2011). Strategies such as electrolytic exfoliation, ball milling or microwave heating are being advanced as the means of obtaining single, few and multi-layered graphene flakes in bulk quantities. Spectroscopic techniques (Raman, SEM, TEM, AFM, XPS, Auger, ARUPS) are being used to understand surface and edge chemistry of graphene. The various techniques are needed since the morphology of graphene sheets changes when they are derived from different synthetic routes. A proper characterization of graphene is critical to understanding and exploiting GPNC properties. To tailor polymer chain length and molecular weight, modern synthetic tools (ATRP, RAFT, NMRP) could be used to develop application-specific GPNCs.

 

Graphene-based composites could be used in well-established technologies (cars, aircrafts, fuel cells etc.) as well as in emerging green-technologies (solar cells, batteries, catalysis). For instance,
transparent and conducting GPNCs could replace indium tin oxide one day. While not necessarily transparent, highly-conducting GPNCs could find applications in nano-electromechanical systems. In structural applications, the buckling resistance of a composite material is of immense practical interest. So is the load transfer and understanding of fatigue life. Studies are piling up to develop engineering data and design guidelines for GPNCs. Then there are applications that can only be dreamed about.

 

One of the major obstacles in the path to progress is to understand the detailed evolution of chemical structures during oxidation/reduction and controlled functionalization of graphene. A range of defects in a graphene-like structure can influence the physico-chemical properties of graphene. The path forward is then to accurately identify the defects and to systematically quantify them. Essentially, these defects pose challenges but also afford opportunities to anchor polymer chains to the surface and thereby maximize the application potential of synthesized GPNCs. Although CNTs and graphene appear
to provide comparable mechanical and electrical properties, graphene-based composites potentially provide larger thermal conductivity enhancements and superior barrier properties than CNT-based composites. Graphene nanocomposites, when used as thermal interface materials, outperform those containing CNT or metal nano-particles due to graphene’s aspect ratio and lower Kapitza
resistance at the composites interface (Khan 2012). The problem with barrier studies, however, is the lack of comprehensive data and a suitable model to better understand barrier properties of GPNCs.

 

Nonetheless, the main challenge that remains: how to produce a large enough volume of graphene safely and in a cost efficient manner. That’s where the stage is set and the race is on.

 

The study of graphene-based polymer nanocomposites is a multi-disciplinary research field. Latest breakthroughs can emerge only when convergent thinking of various fields meet and learn from one another’s work. The tree of knowledge of several branches such as chemistry, physics, and biology to chemical, mechanical, electrical, and civil engineering can allow the rise of graphene to attain its true potential. Meaningful advancements to bridge the gap between GPNC research and its applications are likely to occur only if a broader scientific and engineering perspective is in view. This is what each of the chapter authors, who is a specialist in his or her own field, brings to the fore in the story of Graphite,Graphene, and Their Polymer Nanocomposites. We hope that this book will contribute to the advancement of both science and technology in this exciting area.

 

 

Acknowledgements

One of the editors, Prithu Mukhopadhyay, would like to thank IPEX Technologies Inc. for allowing him to dabble in polymer science and technology with a keen eye for commercial
development of products.


Plasticstrends appreciates the permission granted by CRC press, to publish the introductory chapter from the book “Graphite, Graphene, and Their Polymer Nanocomposites”.  To learn more about the book, please visit http://www.crcpress.com/product/isbn/9781439827796

 

 

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Cai, J.; P. Ruffieux, R. Jaafar et al. 2010. “Atomically precise bottom-up fabrication of graphene nanoribbons”. Nature 466: 470-473.

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Prithu Mukhopadhyay

Prithu Mukhopadhyay is a Scientist with IPEX Technologies Inc. in Montreal, Canada. Since 1997, he has been engaged in R&D as well as manufacturing and quality management for
injection molding and extrusion. He earned his master’s degree in organic chemistry and his Ph.D. in polymer chemistry from the Indian Institute of Technology, Kharagpur. He came to
Montreal, Canada in 1991 as a post-Doctoral fellow in chemical engineering at Ecole Polytechnique after having worked as a chemist for the Oil and Natural Gas Commission of
India. Prithu is passionate about new plastics technologies, and he has been a member of the New Technology Committee of the Society of Plastics Engineers since 1998. He has chaired the
committee in the past, and he has been active in developing New Technology Forums at the Annual Technical Conference of the Society since 2000. He is an expert on plastics piping
materials, and he has published and spoken extensively on this and a variety of polymer topics. He is the founding editor of Plasticstrends, an educational web site that was established in 2000.

Rakesh K. Gupta

Rakesh K. Gupta is George B. and Carolyn A. Berry Professor and Department Chairman of Chemical Engineering at West Virginia University where he has been teaching since 1992. He
holds B. Tech. and Ph.D., degrees in chemical engineering from the Indian Institute of Technology, Kanpur, and the University of Delaware, respectively. Before coming to WVU, he
taught at the State University of New York at Buffalo for 11 years. He has also worked briefly for the Monsanto and DuPont Companies. His research focuses on polymer rheology, polymer
processing, and polymer composites. He has published more than 100 journal papers, 65 conference papers and 12 book chapters on these topics. He also holds three U.S. patents. He is
the author of Polymer and Composite Rheology, the coauthor of Fundamentals of Polymer Engineering and the coeditor of Polymer Nanocomposites Handbook.