Self Assembly of Biophotonic Nanostructures by Phase Separation
We often tend to associate the idea of color in the natural kingdom with pigmented materials. However, many colors that arise in nature come not from pigment but from ordered nanostructures that backscatter light at specific frequencies. One such example arises in certain types of birds, where the feather barbs are actually composed of <math>/beta</math>-keratin and air nanostructures which are quais-ordered and have some characteristic length scale. This paper presents two different types of feather barb nanostructures, that arising in Sialia sialis and that arising in Cotinga maynana, and hypothesizes the physical mechanism by which these nanostructures could have been created.
The plumes of the two bird species S. sialis and C. maynana, shown in the pictures above, both are composed of nanostructured material. For S. sialis, the structures are long tortuous <math>/beta</math>-keratin and air channels, while for C. maynana the structures look more like