Graphene manufacturing

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 Why Graphene?

Every day there are new announcements of amazing feats about what Graphene can achieve; over 100 times stronger than steel, more conductive than copper, yet totally flexible and with a staggering surface area of in excess of 2,500m² per gram. What is the commercial reality in delivering this new nano material and what is their relevance to real products?

Since the ground-breaking experiments in 2004 by Andre Geim and Konstantin Novoselov, researchers have been seeking ways to produce large scale high quality Graphene. The award of the Nobel Prize for Physics to Geim and Novoselov elevated this material onto the world stage and set many hares running amongst the academic, corporate and investment world.

Academic interest lies primarily in what might possibly be achieved in the lab with this new “wonder material.” We see a huge range of examples from the latest bendable phone, to a touch screen that is not coated on glass and so does not shatter; a 3D printed conductive object and on a more commodity level, condoms! The list is endless and consequently the potential market almost unlimited. As such, industry sees it as a massive value added proposition making products “faster, better, cheaper.”

To the investment community it is a high margin return possibility. In other words the “hype” has started.

A further development that fuelled interest and investment from the industrial and academic world at an even faster pace was in November 2011 when the US-based Environmental Protection Agency issued a significant new use rule that advised manufacturers and users of carbon nano tubes (CNT) to treat them as potentially toxic. Industry therefore turned its attention to Graphene as the alternative next “must have” material.

The interest in Graphene, as with nano materials in general, is based around its properties and their ability to change the world we live in today – but can it? Without doubt all of the claimed properties exist through a single layer of hexagonal latticed planar linked perfectly formed carbon atoms. Graphene is 0.3 of a nanometre thick which means that 3million layers would be 1 millimetre high – hardly something that we can readily envisage.

Moving from the Lab to Commercial applications

Evidence of the Graphene opportunity was highlighted by the Intellectual Property Office (IPO) in their recent report ‘Graphene The worldwide patent landscape 2013.’ While Graphene is considered a British discovery (albeit by two eminent Russian Scientists based in Manchester), of the 8,416 patents published  worldwide relating to Graphene by February 2013, only 57 were from the UK, while organisations in China, USA, Korea and Japan held almost 80% of the rest of the patents .

Many of these related to potential applications of Graphene as opposed to the production of the base material.  Given the predominance of uses relating to its conductivity and similar properties and as most of the ultra-capacitor and touch screen manufacturers are located in these countries, the patent proliferation in those territories is not surprising.

Clearly therefore, based on the number of patents being applied on an almost daily basis, academia and industry think it can be made to work and are energetically pursuing ideas.

Image 1:   HDPlas GNP –or- Graphene Nano Platelets – or – Electron Microscope Image of a Haydale’s HDPlas™ GNP.

However, others are not so convinced. The science is complex and as some cynics have put it, “Graphenes advanced properties give it unrivalled ability to separate investors and their money.”  Industry and academia will need to collaborate closely to prove them wrong! How will this happen when often taking an idea from the lab to the industrial world is littered with debris of failing companies and lost money. Fantastic material properties on a lab scale do not always translate into large scale applications that can be made economically. In the case of CNT, if the industrial giant Bayer decided to stop investing in the technology, how can it be achieved with Graphene?  Whilst long term efforts are being made to produce on an industrial scale, the single film “perfect” Graphene sheets by the Far East giants of Samsung, LG and others, there is an interesting alternative. How can we capitalise on the less perfect but equally effective Graphene Nano Platelet (GNP) as a key to short term commercialisation?

The commercial picture is complicated by the fact that there are many different types of Graphene and many target markets. Each type of “Graphene” offers a different set of properties depending on the form in which it arrives; the average flake size, the number of Graphene layers, and the chemical groups existing on the surface of the flakes.

Similarly, each target market also requires different performance levels and cost targets, along with go-to-market strategies. The picture is further complicated by the fact that there are many production techniques, and each technique delivers a different material, cost structure and scalability. No wonder the research departments are struggling to find the material that both works for their application and fulfils their other criteria.

This is a golden era for carbon research with the academics pursuing the perfect analysis tools for these nano materials whilst simultaneously evaluating the growing variants of each sub family and how they must be processed to ensure their potential properties are married to the systems they could enhance. Recognition of the cost benefit of each graphene family almost seems outside the scope of researchers yet must be realised by industry if they are to grasp the enormous potential benefits being offered. There is a massive education process required combining realistic appraisal with the removal of any hype

Image 2: Electron microscope image of Haydale’s HDPlas™ Multi Walled Carbon Nanotubes.

Lessons learned can benefit the future

Often in the race for sales and (hopefully) profit, nano materials have been pushed onto the market as the “one for you” only for the user to find that it was no different from or indeed worse than, say, the materials already being used. It is likely that the blame actually lies with impure materials having defects/voids or the wrong surface chemistry.  Apart from the technical errors, all marketing gurus will advise never sell or try to force into the market a product that has just been discovered or invented rather than finding what the market wants and delivering a solution.

All this seems downbeat and negative – not so. It is reality and we at Haydale believe the properties of Graphene can be realised and that ever form the supply is, dispersing it properly to make a real improvement will be the issue.

The key to this is the ability to properly surface engineer the Graphene nano materials so that they can covalently bond with the target matrix in a way that ensures homogeneous dispersion. Dispersion is the real key to delivering excellent conductivity, thermal heat transfer, barrier films that out-perform current offerings, a workable transparent conductive film, conductive inks and so on. This is not new. In a paper entitled “The mechanics of graphene nano composites: A review” published in July 2012 (https://www.escholar.manchester.ac.uk/uk-ac-man-scw:173015) by four Manchester University Scientists (including Novoselov) concluded that:

“Graphene and Graphene Oxide show promise as reinforcements in high-performance nanocomposites and ……ought to have outstanding mechanical properties.

BUT there are problems in:

• Obtaining good dispersions

• Exfoliation of Graphene into single- or few-layer material with rea             sonable lateral dimensions

• Producing Graphene without imparting significant damage upon        

  the flakes.

It needs; a strong interface between the reinforcement and the polymer matrix to obtain the optimum mechanical and conductive properties.”

To date, the industrial world has tried many methods and some are further ahead than others. Judging by the claims of those making “Graphenes,” the future supply of the base material will not be the problem, certainly for the multi-layered GNP, while no one really knows when the single commercially available Graphene sheet will be available. In whatever form the supply is, dispersing it properly to make a real improvement will be the issue. The current use of chemical and thermal shocking in the conversion of powdered graphite to GNP has scalability but creates defects and is limited by the chemical groups available in the intercalating acids. Leaving aside the environmental aspects, these powders can be produced relatively cheaply until there is a need to add a dispersing agent or some other process to achieve the desired dispersion. Whilst this has met with some success the treatment has cost implications and damages the very structure you are trying to disperse into a material. Additionally the surface chemical the treatment leaves on the “Graphenes” is limited to the groups inherent in the available acids.

Synthetically produced Graphenes are almost certainly going to have to overcome the same issues of dispersions. Some companies remain very coy and even silent in this respect. Carbon, after all, is relatively inert and thus is difficult to bond to and to disperse. Adding free radicals to the surface of the carbons can help in:

• Exfoliating (or liberating) sheets;

• Enhancing particle segregation;

• Improving dispersion; and

• Enabling tailored solutions

Image 3: Haydale graphene inks

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