Structurally colored, thin biopolymer films

POLY 669

Caroline L. Schauer, cschauer@cbis.ece.drexel.edu and Matthew D. Cathell, mdc47@drexel.edu. Department of Materials Science and Engineering, Drexel University, 3141 Chestnut Ave., Lebow 439A, Philadelphia, PA 19104
The natural world is an area where biotechnology and nanotechnology combine to create impressive structures with designed functions. Natural materials that modulate light are among the most intricate nanoscale materials. A number of nature's inhabitants exhibit structural coloration based upon the stacking of thin layers of biomaterials. A biopolymer thin film, of appropriate thickness, is capable of displaying structural color, independent of the material's intrinsic electronic absorption color. Colored, thin polymer films can undergo perceptible color shifts when exposed to selected analytes, such as metallic ions. In our attempts to better understand these processes, we investigated structurally colored thin films of crosslinked alginate, chitosan and chemically modified chitosan. Three independent pathways to crosslink polysaccharides after film formation are also investigated. Structurally colored biopolymer thin films have a variety of potential applications, including use as novel reflective camouflage materials and as a platform for an optics-based sensor.