Ever since its discovery in 2004, graphene has been associated frequently with polymers. The incorporation of graphene into polymers and the resulting end application is dependent on several factors – such as the type of graphene, the graphene production technique used, and the polymer substrate used, just to name a few.
Panoramic shot of GG 3.0, the third iteration of General Graphene’s proprietary industrial-scale CVD graphene production system. Image Credit: General Graphene Corporation
Chemical vapor deposition (CVD) graphene, a one-atom-thick carbon layer, is normally grown on the metallic catalyst material’s surface — with copper being one of the most common growth substrates employed to grow monolayer CVD graphene. CVD graphene transfer has proved to be an essential manufacturing step for its use in certain applications (Bahri et al., 2021) and when it comes to polymers, in most cases, a transfer step is needed.
Due to the substrate-dependent behavior of CVD graphene, the underlying polymer plays an important part in determining different properties — such as electrical or thermal — of the subsequent CVD graphene polymer composite.
Usually, a chemically and thermally stable polymer that does not indirectly dope CVD graphene is ideal when it comes to harnessing the properties of CVD graphene when incorporated into a polymer. CVD graphene polymer composites can be used as conductive coatings, sensing elements, and to develop various flexible electronic devices.
The Challenges of CVD Graphene Transfer
Even with progresses in CVD graphene transfer throughout the industry, many difficulties have limited the scalability potential for large-area CVD graphene transfer. Some of these include the challenge of achieving highly contaminant-free CVD graphene, batch scale restrictions, the use of harsh chemicals, high input and operating costs, and the introduction of defects in the CVD graphene surface due to the transfer-induced tears (Chen et al., 2016).
Wet etch transfer and oxidative decoupling are common transfer methods used for CVD graphene. These methods are batch-scale processes that have been assessed in a roll-to-roll format. Both these methods, however, are chemically intensive and tedious to implement in a roll-to-roll format, thus making it costly and difficult to scale.
Although direct growth and transfer-free production methods have been extensively discussed to alleviate the difficulties of CVD graphene transfer, the main bottleneck is that CVD graphene can only be grown directly on some catalytic substrates. For example, the direct growth of CVD graphene on silicon is hindered by the need for a high growth temperature and poor crystal quality (Avishan et al., 2021).
Advancements in Roll-to-Roll CVD Graphene Transfer
Outfeed view of General Graphene’s proprietary Roll-to-Roll CVD Graphene Transfer system. Image Credit: General Graphene Corporation
Roll-to-roll transfer is still one of the main aims of most companies that produce CVD graphene, but many have found the technique challenging to perfect and scale. General Graphene has made multiple advancements in its transfer technologies and roll-to-roll CVD graphene production to directly resolve the difficulties of creating mass volumes of CVD graphene films at industry-compatible pricepoints and at reproducible qualities customized for particular end applications.
Near the end of 2022, General Graphene finished integrating an inline coating system to GG 3.0, the third iteration of its exclusive roll-to-roll chemical vapor deposition (CVD) production system. This integrated system allows General Graphene to coat a different range of thin polymer films onto a CVD graphene-on-catalyst substrate roll.
The thin polymer film coatings could also be laminated and cured before the subsequent graphene-on-polymer output leaves the GG 3.0 production. The result is fed directly into General Graphene's Roll-to-Roll CVD Graphene Transfer system where the graphene-on-polymer is separated from the catalyst material’s surface.
Roll-to-Roll CVD Graphene Transfer system of General Graphene has been used efficiently to transfer several tens of square meters of roll-to-roll CVD graphene on polymers and has the potential to transfer several hundreds of square meters of roll-to-roll CVD graphene on polymers. The system also has a very small chemical footprint which, as a result, makes it simpler and cheaper to implement at scale.
General Graphene is also able to successfully reuse copper foil – its primary catalyst material – once the graphene-on-polymer has been separated from it. The capability to reuse the catalyst material has been considered a chief driver towards facilitating scalable CVD graphene mass production (Bahri et al., 2021) and General Graphene's advancements in this front have served an important part in driving its direct production cost 2 to 3 orders of magnitude below the industry standard.
The Impact of Large-Area CVD Graphene Polymer Composites
General Graphene has always held the belief that human beings were never meant to handle nanoscale materials. This belief has been the primary driver in its efforts to automate CVD graphene transfer in a way that allows for large-area, minimal defect, low chemical footprint, roll-to-roll transfer of CVD graphene.
General Graphene's Roll-to-Roll CVD graphene transfer and production systems have been configured to support the construction of large-area roll-to-roll CVD graphene films on different polymers such as EVA, PMMA, PI, etc.
General Graphene’s work to advance the roll-to-roll synthesis and transfer of CVD graphene represents an unprecedented breakthrough and paves the way for the development of CVD graphene polymer composites in mass volumes, at a low cost, and at reproducible qualities optimized for specific end applications.
To provide some context, the per unit cost of using CVD graphene on a polymer compatible with a sensor application has been reduced from a few dollars to a fraction of a dollar – representing a paradigm shift in the commercialization of CVD graphene polymer composites.
References:
- Avishan N, Hussain N, Nosheen F (2021) Large-scale Graphene Production and Transfer for Industrial Applications. Materials Innovations 2 (1), 15-25.
- Bahri, Mohamed & Shi, Biao & Khouloud, Djebbi & Elaguech, Mohamed Amin & Zhou, Daming & Ali, Mounir & Tlili, Chaker & Wang, Deqiang. (2021). Toward clean and crackless polymer-assisted transfer of CVD-grown graphene and its recent advances in GFET-based biosensors. Materials Today Chemistry. 22. 10.1016/j.mtchem.2021.100578
- Chen, Gong, X., & Gai, J. (2016). Progress and Challenges in Transfer of Large‐Area Graphene Films. Advanced Science, 3(8), 1500343–n/a. https://doi.org/10.1002/advs.201500343
This information has been sourced, reviewed and adapted from materials provided by General Graphene Corporation.
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