Anusuyadevi, Prasaanth Ravi, Singha, Shuvra, Banerjee, Debashree, Jonsson, Magnus, Hedenqvist, Mikael S. S., Svagan, Anna J. J., Anusuyadevi, Prasaanth Ravi, Singha, Shuvra, Banerjee, Debashree, Jonsson, Magnus, Hedenqvist, Mikael S. S., and Svagan, Anna J. J.
Photonic films based on cellulose nanocrystals (CNCs) are sustainable candidates for sensors, structurally colored radiative cooling, and iridescent coatings. Such CNC-based films possess a helicoidal nanoarchitecture, which gives selective reflection with the polarization of the incident light. However, due to the hygroscopic nature of CNCs, the structural colored material changes and may be irreversibly damaged at high relative humidity. Thus, moisture protection is essential in such settings. In this work, hygroscopic CNC-based films are protected with a bioinspired synthetic plant cuticle; a strategy already adopted by real plants. The protective cuticle layers altered the reflected colors to some extent, but more importantly, they significantly reduced the water vapor permeance by more than two orders of magnitude, from 2.1 x 10(7) (pristine CNC/GLU film) to 12.3 x 10(4) g mu m m(-2) day(-1) atm(-1) (protected CNC/GLU film). This expands significantly the time window of operation for CNC/GLU films at high relative humidity., Funding Agencies|Olle Byggmaestare [194-0679]; Knut and Alice Wallenberg Foundation (WWSC); Linkoeping University; Wallenberg Wood Science Center; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University [2009 00971]