Materials Horizons Blog

In the ever-evolving landscape of materials engineering, researchers are pushing the boundaries of sustainability and functionality. One groundbreaking avenue of exploration is the integration of mycelium, the root-like structure of fungi, into biocomposites. In this blog post, we delve into a recent study that harnesses the unique properties of mycelium through 3D printing and indirect inoculation, resulting in a material with enhanced mechanical strength and diverse applications.

Shen et al. formulated a biocomposite designed to offer mechanical robustness and compatibility with mycelium. To achieve this, the researchers ingeniously selected chitosan and cellulose and introduced leftover coffee grounds as a sustainable source of nutrients. This careful combination created a material that not only exhibited shear thinning behavior, ideal for 3D printing but also laid the foundation for mycelium colonization (Figure 1).

One distinguishing feature of this study is the use of indirect inoculation for mycelium colonization. Traditionally, direct inoculation involves mixing the inoculum with the composite material before printing. However, the researchers chose a different route, incubating printed samples on a bed of live mycelium. This indirect approach, although taking longer for full colonization, turned out to be more effective.

The study of the mechanical properties of biocomposites revealed a strong influence on the orientation of the 3D printing tool path and the alignment of the cellulose fibers. The authors printed parts of different shapes, and the mechanical properties were dependent on the printing design. However, the fully colonized material showed a notable increase in mechanical strength, surpassing previously reported mycelium composites.

 

The influence of mycelium extended beyond mechanical properties to wettability and absorption characteristics. The fully colonized composite developed a smooth hydrophobic “skin,” demonstrating improved water contact angles. Under submerged conditions, the colonized compound demonstrated lower water absorption and volume swelling, attributed to the presence of hydrophobic mycelial hyphae.

The team explored the capabilities of mycelium to develop biosealed mycelium containers as self-sealing living boxes and the creation of flexible textile-like materials through precise 3D printing and mycelium colonization. By printing biocomposite panels with consistent gaps and allowing mycelium to cover them, flexible hinges were formed, enabling the creation of a material capable of bending and stretching in multiple directions.

In conclusion, the fusion of 3D printing, indirect inoculation, and mycelium colonization represents a leap forward in the field of sustainable biocomposites. The mechanical properties, wetting characteristics, and adaptability of the biocomposite open avenues for green alternatives in packaging, textiles, and more.

To find out more, please read:

Robust myco-composites: a biocomposite platform for versatile hybrid-living materials
Sabrina C. Shen, Nicolas A. Lee, William J. Lockett, Aliai D. Acuil, Hannah B. Gazdus, Branden N. Spitzerab  and Markus J. Buehler
Mater. Horiz., 2024, Advance Article, DOI: 10.1039/D3MH01277H

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About the blogger

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Dr. Danila Merino is the PI of the SusBioComp group at POLYMAT and a Materials Horizons Community Board member. Her research focuses on the development of new sustainable biocomposite materials derived from biomass specifically designed to protect and enhance agricultural and food systems with minimal environmental impact.

To address the need for large-scale electrochemical energy storage (EES), much research attention has moved beyond Li-ion batteries due to safety and security-of-supply issues. Sodium, an alkali-metal which is much more abundant and well-distributed globally, is of keen interest as its mining process is cleaner and freer from ethical concern. Moreover, to avoid the high flammability of organic electrolytes, some researchers are looking towards aqueous sodium-ion batteries as a potential contender for future EES systems. This has the added benefit of increasing the ionic conductivity by as much as two orders of magnitude versus organic equivalents, potentially enabling higher rate capability. However, moving from traditional carbonate-based electrolytes to water means a narrowing of the electrochemical stability window and the need for electrodes to facilitate the intercalation and de-intercalation of hydrated cations. Given the smaller accessible voltage and the larger charge carrier, aqueous sodium-ion batteries are still plagued by low specific energy and limited lifespans.

Therefore, the development of new electrode materials to maximise specific capacity is an important research direction. For the anode material, much attention has been paid to the development of polyanionic materials, such as sodium superionic conductors (NASICON), but also carbon-based materials such as polypyrrole and polyimide systems. In recent work by Maria K. Ramos et al., however, the synthesis of a graphene-based composite thin-film was presented, incorporating two compounds that had been shown to have high capacities but suffered from low conductivity and significant volume changes.

Specifically, the researchers highlighted the difficulty of producing ternary thin-films by traditional fabrication routes (e.g., spin-coating, vapour deposition etc.), spurring the development of a liquid-liquid interfacial route (LLIR) for the self-assembly of materials at the interface of immiscible liquids to give a continuous network that can be deposited on any solid substrate. MoS₂, known to facilitate the intercalation and de-intercalation of hydrated sodium ions, and non-toxic copper oxide nanoparticles with high theoretical specific capacity, were combined with graphene in this way to produce ternary films that were electrochemically characterised.

Interestingly, the researchers detailed three different thin-film preparation approaches using their LLIR method (Figure 1). The in-situ approach, whereby graphene oxide and Cu²⁺ were simultaneously reduced in a dispersion of MoS₂, yielded a thin-film anode material that demonstrated a very high specific capacity of 1377 mA h g^-1 (c.f. specific capacity of typical lithium-ion batteries is < 200 mA h g^-1).

In summary, the successful implementation of this in-situ liquid-liquid interfacial method for thin-film preparation provides encouragement for its use to produce other composite electrode materials, and a greater understanding of its scalability. The demonstration of such a high-capacity aqueous sodium-ion battery electrode should encourage greater exploration of this more sustainable, beyond-lithium EES technology.

To find out more, please read:

Nanoarchitected graphene/copper oxide nanoparticles/MoS₂ ternary thin films as highly efficient electrodes for aqueous sodium-ion batteriesMaria K. Ramos, Gustavo Martins, Luiz H. Marcolino-Junior, Márcio F. Bergamini, Marcela M. Oliveira and Aldo J. G. Zarbin
Mater. Horiz., 2023, 10, 5521-5537, DOI: 10.1039/d3mh00982c

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About the blogger

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Dr Josh J Bailey is an Illuminate Fellow at Queen’s University Belfast, focused on the implementation and optimisation of ionic liquids used in polymer electrolyte fuel cells and is a Materials Horizons Community Board member. He received his doctoral degree from University College London, UK, as part of the Centre for Doctoral Training in Advanced Characterisation of Materials, investigating electrode degradation in solid oxide fuel cells. His research interests span fuel cells, lithium-ion batteries, solid-state batteries, and flow batteries, both in terms of the design of novel electrodes, electrolytes, and membrane materials, as well as the study of materials degradation, with a view to improving performance and durability.

For a considerable period, the engine of progress was fuelled primarily by economic incentives. However, this paradigm has shifted due to increased awareness of the environmental consequences of society. Focus has turned towards embracing sustainability as a precursor to assimilating the fruits of progress into industry. This trend leverages the conversion of different waste feedstock like plastics, metals, etc, into new added value matter. The added value matter could be fuels, solvents, organic substrates, new polymers, and functional materials.

Embracing the notion that “the new is often the well-forgotten old,” the use of biomass as a feedstock for materials with practicable qualities has been revisited and revitalized. The biomass is feedstock mainly derived from agricultural and forestry resources, and animal resources. Compared to other waste feedstock, such as plastic, electronic, and construction waste, biomass already fits more within the sustainable economic strategy due to its natural origin. The other side of this coin is the insufficient mechanical properties of biomass-derived materials which leads to poor durability and recyclability of functional materials from biomass.

Recent work from Leixiao Yu, Lingyan Gao, Shengyi Dong and team suggests a supramolecular strategy to overcome these limitations. They reported the conversion of 6 types of biomass (cellulose, guar gum, sericin protein, chitin, corn protein and potato starch) to functional materials via copolymerization with thioctic acid (TA) to afford poly[TA-biomass]. The material formation is driven by hydrogen bonding between TA and the polar functional groups in the biomass. Despite such non-covalent forces being reversible and inherently weaker than covalent bonds, prepared materials are proven to be highly impact resistant. The prepared poly[TA-biomass] is highly adhesive and water-resistant, however, it could be fully depolymerized by simple ethanol treatment and involved in the next cycle of polymerization-utilization without any obvious decay in mechanical strength. This anticipates potential applications of poly[TA-biomass as anti-water, impact resistant materials. The team expanded the potential application directions to the biomedical field by demonstrating high biocompatibility, nontoxicity, and antimicrobial effects towards both gram-positive and negative bacteria, attributed to TA. For instance, the newly prepared poly[TA-biomass] may hold promise for smart packaging or wound healing materials.

This recent work is a perfect example of the “waste to wealth” approach, where materials chemistry assisted in transforming common feedstock into functional materials. Combining waste feedstock with a supramolecular strategy is a promising concept that can be broadened to the use of other types of feedstock (plastic, metal) and a broad family of non-covalent interactions (hydrogen bonding, π- π stacking, hydrophobic effects). At the moment, however, this research directs the attention of the community to biomass as a promising feedstock for functional materials design.

To find out more, please read:

A supramolecular approach for converting renewable biomass into functional materials
Yunfei Zhang, Changyong Cai, Ke Xu, Xiao Yang, Leixiao Yu, Lingyan Gao and Shengyi Dong
Mater. Horiz., 2024, Advance Article, DOI: 10.1039/D3MH01692G

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About the blogger

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Dr Olga Guselnikova is a member of the Materials Horizons Community Board. She recently joined the Center for Electrochemistry and Surface Technology (Austria) to work on functional materials as a group leader. Dr. Guselnikova received her PhD degree in chemistry from the University of Chemistry and Technology Prague (Czech Republic) and Tomsk Polytechnic University (Russia) in 2019. Her research interests are related to surface chemistry for functional materials. This means that she is applying her background in organic chemistry to materials science: plasmonic and polymer surfaces are hybridized with organic molecules to create high-performance elements and devices.