Shrimp shells to serve as the basis for new multi-protective coatings
Chitin derived from shrimps, mushrooms, and other organisms may lead to new 3D-printed, multi-layered polymer coatings to protect soldiers against bullets, lasers, toxic gases, microbes, and other hazards.
Most famous for being the main component in the exoskeletons of arthropods like crustaceans and insects, chitin is also found in the cellular walls of many other organisms, including nematodes, protozoa, and fungi. In recent years, it has found a growing number of applications in agriculture, medicine, and the development of new materials.
Now, a team of University of Houston researchers led by Alamgir Karim, Dow Chair Professor of chemical and biomolecular engineering, is looking at how to turn chitin into a bio-based, biodegradable, high-impact coating for military applications. Under a US$600,000 grant from the US Department of Defense, the goal is not only to produce lighter, tougher body armor, but to develop a printed coating that can protect against projectile impacts, but also lasers, microbes, and poison gas.
Chitin is a derivative of glucose with its long-chain polymer structure held together by acetyl groups. When these groups are removed, the chitin becomes chitosan, which is a less-brittle fiber that is easier to handle and is often sold as a dietary supplement. Though most often harvested from crustaceans, the Houston team is more interested in developing mushrooms as a chitosan source because they enable a more consistent and standardized polymerization process.
To turn the chitosan into a practical coating, the team has been tweaking its atomic surface structure to help it form into functional layers. These layers can be laid down by 3D printing to form different layers with different functions, including a hard impact-resistant one, an energy-absorbing layer that acts like the crumple zone on a motor car, one that absorbs toxic gas using charcoal nanoparticles, and a textile layer for adhesion.
Although the research is aiming at producing multi-protective coatings for military personnel, the team says the project should also have applications for automotive, construction and other industries.
Source: University of Houston