s42004-019-0202-8.pdf (6.56 MB)
Liquid – liquid phase separation morphologies in ultra-white beetle scales and a synthetic equivalent
journal contribution
posted on 2019-09-02, 08:42 authored by Stephanie L Burg, Adam Washington, David M Coles, Antonino Bianco, Daragh Mcloughlin, Oleksandr O Mykhaylyk, Julie Villanova, Andrew JC Dennison, Christopher J Hill, Pete Vukusic, Scott Doak, Simon MartinSimon Martin, Mark Hutchings, Steven R Parnell, Cvetelin Vasilev, Nigel Clarke, Anthony J Ryan, Will Furnass, Mike Croucher, Robert M Dalgliesh, Sylvain Prevost, Rajeev Dattani, Andrew Parker, Richard AL Jones, J Patrick A Fairclough, Andrew J ParnellCyphochilus 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 frac- tions 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.
Funding
Innovate UK (Grant Number 33692-239251) in partnership with AkzoNobel and the University of Sheffield
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Materials
Published in
Communications ChemistryVolume
2Publisher
Springer NatureVersion
- VoR (Version of Record)
Rights holder
© The AuthorsAcceptance date
2019-08-02Publication date
2019-08-29Copyright date
2019eISSN
2399-3669Language
- en
Depositor
Dr Simon MartinArticle number
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