It seems like the next new material innovation can be made from anything in our kitchen fridge. Next-gen, “sustainable” materials have touted mushrooms, bacteria, seaweed, pineapples, cacti, shrimp shells, and more as the next magical ingredient. What, then, are the differences between these different raw materials or inputs? How does working with different types of inputs impact scaling, manufacturing, and the resulting material’s properties?
Using the Material Innovation Initiative’s (MII) 2021 State of the Industry Report as a starting point, this article breaks down sustainable materials into categories based on their primary ingredient: recycled polymers, mycelium, cultivated animal cells, animal byproducts, plants, and microbes. In Part 1 of 2 in this series, we will discuss the differences in creating these materials and their resulting material properties.
“Microbes assemble our materials, while plant-based reagents customize the resulting biofilm with various properties such as durability and handfeel.“
Recycled Fibers
While they are not considered next-gen materials, recycled fibers such as recycled polyester or nylon fabric are important to include as they are the most prevalent “sustainable” materials on the market today. Recycled fibers are typically sourced from plastic bottles. Many claim that this practice removes plastic that would otherwise pollute the oceans. The bottles are broken down into pellets, which can then be melted down and extruded back into a polyester filament.
Many suppliers offer the option of making the same material in either conventional or recycled polyester, as the two different materials will deliver similar performance properties. Recycled fibers often have the benefit of being similarly durable, soft, and hydrophobic, while only being marginally more expensive. They also have a lower carbon footprint than their conventional counterparts.
Despite these upsides, using recycled polyester continues to perpetuate a reliance on fossil fuel-based materials, contributing to a large carbon footprint. Additionally, many of these recycled materials cannot be continuously recycled back into production and end up in landfills.
Mycelium
Mycelium-derived materials have flooded the next-gen material market, with brands from Hermès to Adidas endorsing their use as a sustainable innovation. Mycelia are the “root networks” of mushrooms, which can grow into a fine, strong, interwoven structure. They are found everywhere in nature, creating a vast, interconnected living system.
Scientists have learned to control the growth of this web of mycelia in either liquid or solid organic substrates. Depending on the medium in which the mycelium is grown, it can create a wide range of forms—from solid blocks and foams to flexible leather alternatives. Compared to conventional leather, they save on time and resource-intensive practice of raising livestock.
However, it is important to be aware that current mycelium-based leather alternatives have to go through a finishing process to create a product that compares to what is expected from animal leather. This process often includes a plastic-based coating, which could affect the overall sustainability and end-of-life potential of the material.
Cultivated Animal Cells
Materials made from cultivated animal cells grow animal leather in a lab setting. A small sample of cells is taken without harming the animal and placed in a nutrient-rich solution. There, they can replicate themselves into the cellular equivalent of the desired material.
Using cultivated animal cells creates leather alternatives that exactly resemble animal leather at the cellular level, from handfeel to durability. It produces animal leather without the need to raise and kill the animal. Since the resulting material behaves the same as animal leather, it may be more familiar for both craftspeople and consumers to accept and use.
However, since the resulting material is the same as animal leather, it also needs to be tanned and finished in the same way existing animal leather does. These existing leather post-processing techniques can still use harmful chemicals.
Animal Byproduct
Material innovations derived from animal byproducts include those made from the shells of the fish sauce industry or leathers made from invasive species. These leather alternatives use animal-derived raw materials that would otherwise go to waste or would be harmful to the ecosystem.
These new leather alternatives avoid some of the problems plaguing conventional cow leather. Specifically, these inputs avoid the need for large grazing pastures and a large number of other resources that raising cows requires. They also sometimes empower local fishermen or tradesmen by recruiting these locals to help source the raw materials. However, these materials still perpetuate the use of animal-derived raw materials. Additionally, their inputs are inherently finite and limited.
Plant-Derived
Material innovations derived from plants can range from using agricultural byproducts such as corn to virgin feedstocks such as natural rubber and cork. Plant matter is the most ubiquitous form of life on earth, making it a plentiful feedstock source. Additionally, the diversity in plant matter allows for many properties—durability, water resistance, softness, flexibility, etc.—to be achieved from different combinations of plant-based additives.
These types of materials reduce the reliance on animals and fossil fuels. However, there is a wide range of plant-derived materials, and it is important to ensure that the beneficial aspects of using plant-based feedstocks are not negated by using coatings or curatives derived from fossil fuels.
Microbe-Derived
Microbe-derived materials use microbes such as bacteria or yeast to create novel biomaterials. The microbes are placed in a sugar solution that can be sourced from agricultural waste. As the microbes feed on the sugar, they form nanocellulose as a byproduct. This is the biofilm that becomes the building blocks of a wide range of new materials. When produced as a leather alternative, the resulting materials can have a plush handfeel with a natural grain, and great tensile strength.
Since it is the microbes that are producing the byproduct and, therefore, “assembling” the material, there is potential for this technology to create self-assembling products. Imagine controlling microbes to create an entire garment from scratch! However, while the theoretical possibilities are endless, realistically, yeast and bacteria consortiums can be difficult to engineer. Additionally, the resulting materials can become brittle over time without a coating. As with plant-derived materials, it is important to ensure that the beneficial aspects of using microbe-based feedstocks are not negated by using a fossil fuel-derived coating.
So, Where Does Bucha Bio Fit In?
Not all innovators fall squarely into one category. Some, like Bucha Bio, may be a blend of multiple categories. As a result of understanding the pros and cons of different inputs, Bucha Bio’s bacteria nanocellulose technology has shifted from being solely microbe-derived to being a combination of microbe and plant-derived. This provides us with the benefits of both manufacturing processes. Microbes assemble our materials, while plant-based reagents customize the resulting biofilm with various properties such as durability and handfeel. The resulting material is a mono-material—a completely homogeneous material that does not require additional coatings or backings.
As material innovators continue to work with everything but the kitchen sink, it becomes increasingly important to understand the pros and cons of each type of material. No one material is going to save our planet single-handedly just yet. However, by recognizing the strengths and weaknesses of different materials, we can make the most responsible decisions for different material needs.
Note: Bucha Bio rebranded to Rheom Materials in January 2024 to better reflect their process and offerings. The new name combines the Greek word "rhéō" (meaning "flow") and "form," describing how a melt-extruder works, where the biopolymers flow into place and then solidify, or form, the final product.
