Chitosan Bioplastic

Wyss Institute researchers molded a series of chess pieces from chitosan bioplastic to demonstrate this promising step towards mass-manufacturing large 3D objects with complex shapes out of fully compostable materials.

A fully degradable bioplastic isolated from shrimp shells could provide a solution to planet-clogging plastics

On our planet and across many industries there is an urgent need for sustainable materials that can be mass-produced. Humans produce 300 million tons of plastic per year and recycle only 3%, leaving the other 97% to rot in oceans and landfills where they harm the food chain and our environment.

A large number of bioplastics on the market today are made from cellulose, a plant-based polysaccharide material, finding application in packaging and simple containers for food or drinks. However, engineers have been unable to shape these materials into complex 3D shapes that can be mass-manufactured, while providing the hardiness characteristic of every day plastics.

The Wyss Solution

Wyss Institute researchers have developed a fully degradable bioplastic isolated from shrimp shells. The new material can be molded into objects that exhibit many of the same properties as those created with synthetic plastics, but without the environmental threat.

The bioplastic is partly made of chitosan – a form of chitin that is the second most abundant organic material on Earth. Chitin is a tough polysaccharide that is responsible for the hardy shells of shrimp and other crustaceans, armor-like insect cuticles, and flexible butterfly wings.

Unlike other plant-based versions, the Institute’s chitin-based bioplastic does not compete with land or other resources for basic human needs. It embodies the next iteration of Shrilk - a material that replicates the unique properties of living insect cuticle composed of chitin from shrimp shells and a fibroin protein from silk.

The chitosan bioplastic can be modified for use in water and easily dyed by changing the acidity of the chitosan solution. The dyes used to color these plastic cups and egg cartons can be collected during the recycling process for reuse.

The Wyss Institute team developed a new way to process this bioplastic, making it even cheaper and easier to make. The novel fabrication method preserves the strong mechanical properties of chitosan, resulting in a tough, transparent material that can be used to fabricate large 3D objects with complex shapes using traditional casting or injection molding manufacturing techniques.

As a cheap, environmentally safe alternative to plastic, the chitosan bioplastic could be used to make trash bags, packaging, and diapers that break down in just a few weeks while releasing rich nutrients that support plant growth.

Potential Applications

• Large-scale manufacturing of consumer products
• Fertilizer