An alternative to plastic packaging thanks to the combination of cellulose and ceramic

Resulting from the work of two research laboratories, the start-up Cilkoa is developing a process consisting of depositing a nanometric layer of ceramic on a sheet of cellulose. The new material obtained has barrier properties similar to those of plastics, as it is completely decomposable and recyclable. Meeting with the co-founders of the company.

Packaging, bottles, labels … plastic single-use items are present in our daily lives. They were chosen for their harmful impact on the environment, as they do not decompose after use, but break down into microparticles found everywhere, especially in the oceans. Reducing this waste is therefore a major environmental challenge. In Grenoble, researchers have developed a material that is flexible and biodegradability of paper, while possessing the barrier properties of plastic, i.e., it is resistant to water and impermeable to gases. Their recipe? They deposited a nanometric layer of ceramic on a sheet of cellulose. This process is the result of the research work of two laboratories, who have combined their expertise, each in their own field: SIMAP (Science and engineering of materials and processes) which specializes in ceramic materials, and LGP2 (Process engineering laboratory papermakers) which , as its name suggests, specializes in paper making. Just created a start-up to promote this new technology. Interview with Frédéric Mercier and Erwan Gicquel, two of the four co-founders of Cilkoa. The first is also a CNRS researcher at SIMAP and the second, a former doctoral student at LGP2.

Engineering Techniques: How do you manage to deposit a thin layer of ceramic on cellulose?

Frédéric Mercier (left) and Erwan Gicquel (right), two of Cilkoa’s four co-founders. Credits: Cilkoa

Frederic Mercier: Cellulose materials have interesting chemical bonds on their surface, called OH groups (or hydroxyl groups), which are capable of reacting with an organometallic compound, with particular being a precursor of ceramics. It comes in the form of a gas and will interact with OH bonds to form a very thin ceramic coating (less than 50 nanometers) over the entire surface of the paper. Some ceramic atoms are thus grafted to each cellulose fiber. It’s like putting a ceramic shell around each fiber.

What difficulties do you need to overcome to complete this process?

Erwan Gicquel: Typically, this process, called ALD (Atomic layer deposition), is used in a clean room, with smooth, non -abrasive materials, and in a dust -free environment. It is particularly used in the field of microelectronics. Therefore, this technology is light years away from the world of paper making, where there is dust everywhere, the materials are rough, massive …

This process for depositing a nanoscale layer of ceramic on cellulose already exists in the literature, but is only suitable for surfaces with a few cm². All of our research work, which began in 2018, consists in making it compatible with the volumes of the packaging industry, whose needs reach several hundred million m². We conducted many experiments to test different operating points, on different sheets of paper. We combined this work with simulation, to understand how this gas is introduced into each cellulose fiber. We also developed methods to accurately determine the presence of several nanometers of this ceramic across the surface of the papers.

How is your new material performing?

FM: Cellulose has many interesting properties, but does not support water. From the slightest trace of moisture, it is destroyed and there is no longer any mechanical strength in this support. Thanks to the deposition of a nanometric layer of ceramic, cellulose becomes inert to water vapor, liquids and gases. For example, it is possible to make a hydrophobic paper or one with a gas barrier effect. These properties are obtained only thanks to a few nanometers of ceramic grafted on the surface of each cellulose fiber; it is not a coating or varnish that can stir or peel. Chemical bonds are closely related to the surface of the fiber.

Ultimately, we obtain a material whose barrier properties are similar to those of plastics and consist of more than 99.9% cellulose and some ceramic atoms. This coating is completely transparent and printable; you will not see the difference between treated and untreated role. And, good news, this material shrinks like paper, in composting or recycling conditions. This is an innovation that has no equivalent in the market.

What apps are you targeting?

EG: We target all single-use packaging in the broadest sense, which currently cannot be recycled, whether food or cosmetics. We have developed a strategy to reach the market step by step. We will start with packaging for dry products, then gradually move towards those that contain liquid products, such as yogurt cups. In this context, we also offer an alternative to today’s complex packaging, such as packets of crisps that contain several layers, including a metal one.

At what stage of development is your project?

FM: We will only be able to start-up on June 1. From a technology and industrialization perspective, we will need to undertake resizing, so that our process is compatible with customer demands. We are already in contact with food manufacturers, who have shown interest in our product.

Our business model, at the very beginning, is the provision of service, to modify the cellulosic material of our customers. They will bring us their cellulosic materials and our duty is to glue our ceramic coating. We will also advise them on materials.

Our goal is to commission our first plant in 2024/2025, but in the meantime, we are working with our customers to qualify materials and coatings in concrete applications. With our pilot reactors, located in the SIMAP laboratory where we collaborate, we still meet production needs for small series.

We are at the right “timing” to meet the needs manufacturers are facing in the 2025 deadline; a date by which most plastics should be gone from single-use packaging. We have already validated our economic model, meaning we can offer packaging material with barrier functions, fully biodegradable and recyclable, for a cost consistent with the market.

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