Bug wings inspire low-cost, biodegradable material
We are addicted to plastic. For a material that's only been around for about 60 years, we sure do like to use (and waste) a lot of it.
In 2010, the EPA estimates that the United States alone generated almost 14 million tons of plastics as containers and packaging, almost 11 million tons as durable goods, such as appliances, and almost 7 million tons as nondurable goods, like plates and cups. A scant 8 percent of this plastic was recovered for recycling.
We need to find a replacement for this toxic, oil-based, hard-to-recycle material, and fast.
Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University think they may have found the answer in something very small and seemingly insignificant - insect cuticles.
According to the study, published late last year in Advanced Materials, insect cuticles (the lines you see in the wings above) are some of the toughest, strongest, and most versatile structures in the natural world. The cuticle provides protection, both from physical and chemical strains, without adding bulk or weight. It also varies its properties, from rigid along the insect's body segments and wings to elastic along its limb joints.
These unique and highly desirable qualities come from the cuticle's composition–it's made of chitin, a polysaccharide polymer, and protein organized in a laminar, plywood-like structure.
By recreating the unique chemical interactions that occur between these substances, the scientists were able to engineer a thin, clear film that has the same composition and structure as insect cuticle. The material is called Shrilk because it is composed of fibroin protein from silk and from chitin, which is commonly extracted from discarded shrimp shells.
Shrilk is similar in strength and toughness to an aluminum alloy, but it is only half the weight. It is biodegradable and can be produced at a very lost cost, since chitin is readily available as a shrimp waste product. As such, it could provide a low-impact, yet highly versatile substitute to petroleum-based plastics in the near future.