Tufts University scientists have broken down silkworm cocoon fibers into their protein components, and then re-purposed the proteins to form a novel leather-like material.
This is of immense value when one considers how leather production has been impacting our environment in a severe manner.
The multi-billion dollar leather industry requires no less than 3.8 billion bovine animals to sustain production each year. The industry is also known for being a prime culprit when it comes to deforestation, water and land overuse, environmental pollution, and greenhouse gas emissions.
In order to develop the new leather-like material, Tufts scientists first broke down silk fibers to their individual protein components in a water-based slurry.
The next step was printing a base layer of chitosan containing a non-toxic plasticizer glycerol and dye, by extrusion through a tiny bore nozzle onto a surface to provide flexibility and strength to the material.
The plasticizer was then combined with a layer of silk fibrion and thickener from vegetable gum, and then printed on top of the base layer.
“Our work is centered on the use of naturally-derived materials that minimize the use of toxic chemicals while maintaining material performance so as to provide alternatives for products that are commonly and widely used today,” says professor Fiorenzo Omenetto, director of the Tufts Silklab where the material was created.
“By using silk, as well as cellulose from textile and agricultural waste and chitosan from shell-fish waste, and all the relatively gentle chemistries used to combine them, we are making progress towards this goal.”
According to Omenetto, the silk-based leather can be fabricated using computerized 3D layering to create micropatterns, macropatterns and non-regular geometrical patterning.
It can withstand the folding, piercing, and stretching typically used to create leather goods, including the ability to stitch together pieces of material and attach hardware such as rivets, grommets, handles and clasps.
Such silk-leather products can be later re-dissolved and regenerated into its gel-like stock matter, and then re-printed into new products.
Unlike other leather-like, petroleum-based materials in existence, Tufts’ new silk-based leather utilizes only mild chemicals, can be conducted at room temperature, and produces mostly non-toxic waste.
Image and content: Silklab/Tufts University