TY - JOUR
T1 - Liquid–liquid phase separation morphologies in ultra-white beetle scales and a synthetic equivalent
AU - Burg, Stephanie L.
AU - Washington, Adam
AU - Coles, David M.
AU - Bianco, Antonino
AU - McLoughlin, Daragh
AU - Mykhaylyk, Oleksandr O.
AU - Villanova, Julie
AU - Dennison, Andrew J.C.
AU - Parnell, Steven R.
AU - More Authors, null
PY - 2019
Y1 - 2019
N2 - Cyphochilus beetle scales are amongst the brightest structural whites in nature, being highly opacifying whilst extremely thin. However, the formation mechanism for the voided intra-scale structure is unknown. Here we report 3D x-ray nanotomography data for the voided chitin networks of intact white scales of Cyphochilus and Lepidiota stigma. Chitin-filling fractions are found to be 31 ± 2% for Cyphochilus and 34 ± 1% for Lepidiota stigma, indicating previous measurements overestimated their density. Optical simulations using finite-difference time domain for the chitin morphologies and simulated Cahn-Hilliard spinodal structures show excellent agreement. Reflectance curves spanning filling fraction of 5-95% for simulated spinodal structures, pinpoint optimal whiteness for 25% chitin filling. We make a simulacrum from a polymer undergoing a strong solvent quench, resulting in highly reflective (~94%) white films. In-situ X-ray scattering confirms the nanostructure is formed through spinodal decomposition phase separation. We conclude that the ultra-white beetle scale nanostructure is made via liquid–liquid phase separation.
AB - Cyphochilus beetle scales are amongst the brightest structural whites in nature, being highly opacifying whilst extremely thin. However, the formation mechanism for the voided intra-scale structure is unknown. Here we report 3D x-ray nanotomography data for the voided chitin networks of intact white scales of Cyphochilus and Lepidiota stigma. Chitin-filling fractions are found to be 31 ± 2% for Cyphochilus and 34 ± 1% for Lepidiota stigma, indicating previous measurements overestimated their density. Optical simulations using finite-difference time domain for the chitin morphologies and simulated Cahn-Hilliard spinodal structures show excellent agreement. Reflectance curves spanning filling fraction of 5-95% for simulated spinodal structures, pinpoint optimal whiteness for 25% chitin filling. We make a simulacrum from a polymer undergoing a strong solvent quench, resulting in highly reflective (~94%) white films. In-situ X-ray scattering confirms the nanostructure is formed through spinodal decomposition phase separation. We conclude that the ultra-white beetle scale nanostructure is made via liquid–liquid phase separation.
UR - http://www.scopus.com/inward/record.url?scp=85071927482&partnerID=8YFLogxK
U2 - 10.1038/s42004-019-0202-8
DO - 10.1038/s42004-019-0202-8
M3 - Article
AN - SCOPUS:85071927482
SN - 2399-3669
VL - 2
JO - Communications Chemistry
JF - Communications Chemistry
IS - 1
M1 - 100
ER -