Leather-like Materials Research Articles

Eco-friendly production of leather-like material from bacterial cellulose and waste resources

In recent years, resource optimization has been recognized as a top priority among many challenges. Studies have indicated that valuable products can be created by combining natural or discarded resources with cutting-edge biosynthesis techniques. This approach is considered foundational for establishing a “zero-waste” socio-economic structure. This research focuses on optimizing resources and minimizing environmental impacts, especially within the manufacturing and fashion sectors. An innovative leather-like material named BC-BioLeath (Bacterial Cellulose-Based Bio Leather) has been introduced. BC was produced by the fermentation of coconut water, a byproduct of the food industry. Traditional leather-like processing, including tanning, was applied to BC using food waste such as oxidized edible oil and coffee grounds, along with timber industry by-products like vegetable tannins. Studies involving SEM observation, mechanical, style, and dyeing performance testing revealed that the product, BC-BioLeath, exhibited superior mechanical properties. For instance, BC crosslinked with oxidized edible oil showed a tensile strength of 82.14 MPa, surpassing traditional cowhide used in shoe uppers by 2.08 times. When plasticized with glycerol, the tensile strength reached 56.19 MPa, with breaking elongation of 36%. Beyond its mechanical prowess, the product also achieved economic and environmental benefits through waste repurposing, contributing to a natural energy cycle. BC-BioLeath was identified as a more humane and eco-friendly leather alternative. This method showcased not just efficient waste repurposing but also introduced a novel, microbe-focused sustainable production approach. Such a model offered a genuine circular economy solution for high-polluting sectors, such as the leather fashion industry. A cost analysis showed that BC-BioLeath's production cost of $97.92/m2 (excluding labor and operating costs: $7.52/m2) was within the commercial leather range of $39.7 to $220.8/m2. This indicated its sustainability as a competitive alternative.

Life cycle assessment (LCA) of leather-like materials from mycelium: Indonesian case study

Life cycle assessment (LCA) of leather-like materials from mycelium: Indonesian case study

An approach towards identification of leather from leather-like polymeric material using FTIR-ATR technique

AbstractLeather, a by-product of the meat industry, has unique strength, elasticity, water vapor permeability, resistance to abrasion, durability, and longevity. In the background of ISO 15115:2019, the authenticity of leather has become a subject matter of concern. There is a need to distinguish leather (animal origin) from other leather-like materials derived from fossil fuel (PU, faux leather, etc.) and agro-product-driven vegan materials, which are also sold in the market as leather. For this purpose, this work relies on the signature FTIR bands of collagen (the skin-making protein) as a starting point to distinguish between animal origin and rest. A detailed investigation of all types of materials used in lifestyle products has been carried out to assess the boundary lines of this hypothesis. It is reasonably concluded that the signature Amide I, II, and III bands of collagen occurring at 1600, 1500, and 1200 cm−1 could serve as the first line to distinguish against all materials other than nylon and in the case of nylon, and the Amide A band at 3200 cm−1, forms the basis for differentiation from nylon. In essence, the FTIR spectra can be used as a robust, easy and unambiguous technique to distinguish leather from leather-like materials currently available on the market. Graphical Abstract

Growing mycelium leather: a paste substrate approach with post-treatments

Abstract This research investigates a novel method for cultivating mycelium-based leather substitutes using a carefully formulated paste consistency substrate. The primary objectives are to enhance nutrient availability, facilitate scalability, and streamline cultivation processes. The study spans a 21-day cultivation period, during which a flower-based medium is employed, eliminating the need for labor-intensive harvesting techniques. Two fungal species, Ganoderma lucidum (rishi) and Pleurotus djamor (pink oyster) are tested to assess their compatibility with the growth method. These species were chosen based on their rapid colonization rates and inherent resilience. The investigation delves into various combinations of crosslinking agents, including glycerol (a plasticizer), commercial tanner, citric acid, and magnesium sulfate. The effects of these agents on tensile strength are compared and qualitative data is analyzed through the use of scanning electron microscopy (SEM) and stereo microscopy. Furthermore, the study explores the fabrication potential of non-woven textiles derived from mycelium, emphasizing their suitability as eco-friendly leather alternatives. Scaled prototypes are highlighted to demonstrate their feasibility. Post-treatment processes, such as dyeing with bio-based dyes and acrylic leather paint, are evaluated for their aesthetic impact. The research contributes a biodegradable material alternative that addresses the environmental challenges of high textile consumption. The findings add to the growing body of sustainable design methods in the realm of leather-like materials in bio-design.

Fabrication of leather-like yarns using waste leather for textile application

The escalating focus on emulating natural textiles has prompted a concurrent surge in research aimed at developing leather-like materials. However, traditional leather products are mostly represented as sheets or blocks, which limit their reprocessing. Therefore, in this study, waste leather scraps were processed into powders with an average particle size of 5–10 μm. Subsequently, these recycled powders were wet-spun alongside a polyurethane matrix and polyester yarn to fabricate leather-like yarns. The leather-like yarns prepared in this study had good hygroscopic properties, mechanical properties (51.71 % strain and 4.49 cN/tex), and environmental stability (no more change withstood 24 h of bending, 50 cycles of immersion in 75 % ethanol solution, and 7 d of high and low temperature treatment). A no-salt and low-temperature dyeing method is further used to prepare color leather-like yarns, which requires less energy than polyester. These results provide guidance for the transition of recycling leather waste move to application, enabling the timely advancement of reusing leather waste initiatives in the textile industry.

Functionalization of Bacterial Cellulose and Related Surfaces Using a Facile Coupling Reaction by Thermoresponsive Catalyst.

Recently, bacterial cellulose and related materials attracted significant attention for applications such as leather-like materials, wound healing materials, etc., due to their abundance in pure form and excellent biocompatibility. Chemical modification of bacterial cellulose further helps to improve specific properties for practical utility and economic viability. However, in most cases, chemical modification of cellulose materials involves harsh experimental conditions such as higher temperatures or organic solvents, which may destroy the 3-dimensional network of bacterial cellulose, thereby altering its characteristic properties. Hence, in this work, we have adopted the Suzuki coupling methodology, which is relatively unexplored for chemically modifying cellulose materials. As the Suzuki coupling reaction is tolerable against air and water, modification can be done under mild conditions so that the covalently modified cellulose materials remain intact without destroying their 3-dimensional form. We performed Suzuki coupling reactions on cellulose surfaces using a recently developed thermoresponsive catalyst consisting of poly(N-isopropylacrylamide) (PNIPAM)-tagged N-heterocyclic carbene (NHC)-based palladium(II) complex. The thermoresponsive nature of the catalyst particularly helped to perform reactions in a water medium under mild conditions considering the biological nature of the substrates, where separation of the catalyst can be easily achieved by tuning temperature. The boronic acid derivatives have been chosen to alter the wettability behavior of bacterial cellulose. Bacterial cellulose (BC) obtained from fermentation on a lab scale using a cellulose-producing bacterium called Gluconacetobacter kombuchae (MTCC 6913) under Hestrin-Schramm (HS) medium, or kombucha-derived bacterial cellulose (KBC) obtained from kombucha available in the market or cotton-cellulose (CC) was chosen for the surface functionalization to find the methodology's diversity. Movie files in the Supporting Information and figures in the manuscript demonstrated the utility of the methodology for fluorescent labeling of bacterial cellulose and related materials. Finally, contact angle analysis of the surfaces showed the hydrophobic natures of some functionalized BC-based materials, which are important for the practical use of biomaterials in wet climatic conditions.

Leather-like materials by cellular agriculture

Leather, a popular material in a wide array of industries, is traditionally sourced from animal hides. The scale of production has increased over time, leading to ever-greater concerns about the environmental, ethical and health impacts of leather manufacture. The substantial resources required, plus the pollution and waste generated, pose serious doubts over the sustainability of existing production systems and their ability to meet the increasing demand for leather-like materials. To address these issues, alternatives to leather have been developed. Up to now though, these materials have been unable to perform as well as genuine leather, either mechanically, aesthetically or texturally. Some of the polymer-based alternatives may even be more harmful to the environment than leather itself. The need for a more-suitable leather substitute has coincided with the emergence of cellular agriculture technologies. In the future, it is hoped that leather-like materials may be engineered from collagen created by cellular agriculture, instead of relying upon animal slaughter. Such a material could offer great design, sustainability, environmental and ethical benefits over real leather. Whilst there is significant potential, more investment in research and development is needed before the technology can be considered sufficiently well developed. So far, tissue-engineering techniques applied from clinical fields have proven too costly and inefficient for scaling up, but work has already commenced to identify sources of collagen and cell growth media that are less animal-dependent and not so expensive. Even so, more-efficient methods of controlling the collagen network structure still need to be created. The new round of research is therefore expected to focus upon increasing cell-culture efficiency using, for example, specialised bioreactors.

Incorporations of gold, silver and carbon nanomaterials to kombucha-derived bacterial cellulose: Development of antibacterial leather-like materials

Bacterial cellulose (BC), derived from kombucha scoby have extraordinary organoleptic properties suitable for development of leather-like materials. An improvement in physical and mechanical property is desirable for the practical applications. This work deals with the treatment of BC by incorporations of three different nanomaterials such as gold nanoparticles (AuNP), silver nanoparticles (AgNP) and graphene oxide (GO). Achieving combined benefits via synergic interactions of different nanomaterials is the major objective herein. While graphene oxide can influence some of the parameters related to mechanical properties, silver nanomaterials can offer antibacterial characteristics. Gold nano materials can bridge the BC/silver/graphene oxide as well as provide the desirable aesthetic colour. Different physical chemical and mechanical characteristics were studied in detail. For example, changes in morphology by imaging fiber network were studied using scanning electron microscopy. Fibre properties were studied by Small Angle X-Ray Scattering (SAXS) and X-Ray Diffraction (XRD). Elemental composition was studied by X-ray photoelectron spectroscopy (XPS) analysis and Raman analysis. The improvement of hydrophobicity was studied by Contact angle meter. Thermal analysis was performed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). A Picture was provided in ESI to show the modified material's leather-like appearances.

Collection and Characterization of Wood Decay Fungal Strains for Developing Pure Mycelium Mats.

Wood decay fungi (WDF) seem to be particularly suitable for developing myco-materials due to their mycelial texture, ease of cultivation, and lack of sporification. This study focused on a collection of WDF strains that were later used to develop mycelium mats of leather-like materials. Twenty-one WDF strains were chosen based on the color, homogeneity, and consistency of the mycelia. The growth rate of each strain was measured. To improve the consistency and thickness of the mats, an exclusive method (newly patented) was developed. The obtained materials and the corresponding pure mycelia grown in liquid culture were analyzed by both thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) to evaluate the principal components and texture. TGA provided a semi-quantitative indication on the mycelia and mat composition, but it was hardly able to discriminate differences in the production process (liquid culture versus patented method). SEM provided keen insight on the mycelial microstructure as well as that of the mat without considering the composition; however, it was able to determine the hyphae and porosity dimensions. Although not exhaustive, TGA and SEM are complementary methods that can be used to characterize fungal strains based on their desirable features for various applications in bio-based materials. Taking all of the results into account, the Fomitopsis iberica strain seems to be the most suitable for the development of leather-like materials.

Blocking and Deblocking of Diisocyanate to Synthesize Polyurethanes.

Diisocyanates, particularly toluene diisocyanate (TDI), are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives and insoles, etc. Blocking agents can be used for the operational simplicity and to reduce the hazards of TDI. In this paper, we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle analysis and differential scanning calorimetry (DSC) were used for the characterization. The effectiveness of the blocking was confirmed by spectroscopic techniques. The DSC thermogram showed that blocked adducts deblock at 240 °C, causing the regeneration of TDI, and causing the diisocyanates to react with polyols of different molecular weights, forming polyurethanes. The characterization of the polyurethanes was performed by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a contact angle study.

Manufacturing of animal products by the assembly of microfabricated tissues.

With the current rapidly growing global population, the animal product industry faces challenges which not only demand drastically increased amounts of animal products but also have to limit the emission of greenhouse gases and animal waste. These issues can be solved by the combination of microfabrication and tissue engineering techniques, which utilize the microtissue as a building component for larger tissue assembly to fabricate animal products. Various methods for the assembly of microtissue have been proposed such as spinning, cell layering, and 3D bioprinting to mimic the intricate morphology and function of the in vivo animal tissues. Some of the demonstrations on cultured meat and leather-like materials present promising outlooks on the emerging field of in vitro production of animal products.

Additively manufactured leather-like silk protein materials

Biomaterial composites based on reformulated silk protein offer new routes for tough and strong, environmentally friendly leather-like materials. We present here silk-based biomaterial formulations that are scalable, amenable to digital manufacturing, thus enabling a wide variety of formats, and offering new pathways to sustainable production. Performance is tuned by controlling silk protein conformations at the molecular scale, by introducing other biomaterials and natural additives, and by computerized fabrication providing programmable layering and non-regular geometrical patterning. The resulting materials display strong, soft, pliable, durable, and biodegradable features. Further, these leather-like blends can be augmented by embedding and stabilizing active molecules for sensing of the environment surrounding them.

Measurement of the Inside Microclimate of Footwear Constructed from Different Material Sets

The aim of the research was to determine the effect of footwear materials used on the microclimate inside shoes and to identify which material set provides optimal comfort to users. The microclimate of the interior of 21 pairs of footwear was tested. Selected nonwovens, natural leather, and leather-like materials were used to make the upper, lining and insole lining. Determined was the amount of water absorbed on the sock fibres, and measurement was taken of the relative humidity and temperature, as well as the permeability and sorption of outer materials and lining elements.Results of the researches carried out showed that in order to ensure adequate footwear comfort, materials for the upper should have high permeability, while lining materials should have both high sorption and permeability.

Preparation and Characterization of Nonwoven Fibrous Biocomposites for Footwear Components.

Chromium-tanned leathers used in the manufacture of footwear and leather goods pose an environmental problem because they contain harmful chemicals and are very difficult to recycle. A solution to this problem can be composite materials from tree leaves, fruit residues and other fibrous agricultural products, which can replace chromium-tanned leather. The present study describes the preparation of biocomposite leather-like materials from microbial cellulose and maple leave fibers as bio-fillers. The formulation was optimized by design of experiment and the prepared biocomposites characterized by tensile test, FTIR, DMA, SEM, adhesion test, volume porosity, water absorptivity, surface wettability and shape stability. From the viewpoint of future use in the footwear industry, results obtained showed that the optimized material was considerably flexible with tensile strength of 2.13 ± 0.29 MPa, elastic modulus of 76.93 ± 1.63 MPa and porosity of 1570 ± 146 mL/min. In addition, the material depicted good shape stability and surface adhesive properties. The results indicate that a suitable treatment of biomass offers a way to prepare exploitable nonwoven fibrous composites for the footwear industry without further burdening the environment.

Improved Hydrophobicity of a Bacterial Cellulose Surface: Click Chemistry in Action.

The vast application potentials of bacterial cellulose (BC)-based materials for developing leather-like materials, wound-healing materials and electronic materials have been realized very recently. Surface functionalization of these materials can help in improvement of certain properties such as water repellency, mechanical strength, and so forth. In this paper, we reported functionalization of BC surfaces using "click" polymerization for the first time. By this methodology, dense aromatic groups have been incorporated for the improvement of hydrophobicity. For comparative studies, various fluorine-based compounds have been introduced using conventional click reactions. The surface-modified BC materials have been confirmed by various spectroscopic methods. Particularly, the chemical structures of the materials were studied by solid-state 13C NMR spectroscopy and attenuated total reflection-infrared spectroscopy. X-ray photoelectron spectroscopy was used to study the elemental composition of the materials. Moreover, the crystallite changes of modified BC surfaces were investigated by X-ray diffraction. Further, the changes in the morphology of the material after functionalization were evaluated by scanning electron microscopy and atomic force microscopy. Finally, water contact angle measurement revealed manyfold increase in hydrophobicity after click polymerization. A video is also provided in the Supporting Information to show the application potential of this material for developing leather-like materials.

Evonik invests in animal-free leather firm

Evonik Industries’ venture capital arm has invested an undisclosed sum in Modern Meadow, which is developing leather-like materials that are animal-free. Modern Meadow’s process starts with collage...

Non-medical applications of tissue engineering: biofabrication of a leather-like material

Most tissue engineering efforts are focused on applications in regenerative medicine to improve the quality of life of patients. Despite spectacular progress in the last 20 years, the expected breakthrough to replace dysfunctional tissues in the organism or mitigate the chronic shortage of donor organs has not yet been achieved. This is not surprising, given the enormous challenge facing the biofabrication of complex living structures in vitro and the associated astronomical expenditures. Here, we propose a more modest but more realistic utilization of the knowledge accumulated in tissue engineering and associated biofabrication technologies over the years. We describe specific efforts to engineer the particular compartment of a complex tissue, the skin that gives rise to a commercially useful leather-like material. We take the reader through the entire process from the sourcing of collagen-secreting cells, to the engineering, tanning and final finishing of the material. We analyze the composition, structure, and physical properties of the final product. We compare our process with that followed by the leather industry to point out the advantages and disadvantages of both.

Some New Directions of Development of Polymers and Plastics

Three new possibilities of obtaining resins and plastics are shortly signalised. New liquid anhydrous reactive solvents (RSs) have been obtained from different compounds containing active hydrogen atoms and formaldehyde have been obtained. These RSs dissolve monomers condensating with formaldehyde, especially melamine (Mel) and urea into anhydrous solutions, liquid at temperature of dissolving, containing up to 100% of polymerising substances and up to 70% Mel. At temperature of dissolving these solutions can be fast formed and cured, combining synthesis with processing of polymers in the common process of reactive forming. They can be used for fast bonding of natural fibers. Plastified PVC crosslinks with aliphatic amines under gelling conditions into synthetic poromeric leatherlike materials with hygienic properties of natural leather and 30–40% water vapour sorption and desorption. It was found out that new ecological polyurethanes can be obtained from vegetable oil. urea and formaldehyde

Hygienic leather-like materials from crosslinked PVC

Hygienic leather-like materials from crosslinked PVC

Footwear Materials: The Challenge of Synthetics

The market for leather and leather-like materials is not confined to shoe uppers. There are also linings, insocks, insole covers, bindings, insoles and stiffeners. In spite of synthetics, leather has retained the major share of the shoe upper material market, particularly in men's footwear. But the threat of further inroads into leather's remaining market remains. We assess the synthetic rivals, their properties, their market share and likely developments.