Melville Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Cambridge, Lensfield Road, CB2 1EW, UK.
Adv Mater. 2017 Aug;29(32). doi: 10.1002/adma.201701469. Epub 2017 Jun 21.
The self-assembly of cellulose nanocrystals is a powerful method for the fabrication of biosourced photonic films with a chiral optical response. While various techniques have been exploited to tune the optical properties of such systems, the presence of external fields has yet to be reported to significantly modify their optical properties. In this work, by using small commercial magnets (≈ 0.5-1.2 T) the orientation of the cholesteric domains is enabled to tune in suspension as they assemble into films. A detailed analysis of these films shows an unprecedented control of their angular response. This simple and yet powerful technique unlocks new possibilities in designing the visual appearance of such iridescent films, ranging from metallic to pixelated or matt textures, paving the way for the development of truly sustainable photonic pigments in coatings, cosmetics, and security labeling.
纤维素纳米晶体的自组装是制备具有手性光学响应的生物源光子薄膜的一种有效方法。虽然已经开发了各种技术来调整此类系统的光学性质，但尚未有报道称外部场能够显著改变它们的光学性质。在这项工作中，通过使用小型商用磁铁（约 0.5-1.2 T），可以在组装成薄膜时调整悬浮液中胆甾相的取向。对这些薄膜的详细分析表明，它们的角响应可以得到前所未有的控制。这种简单而强大的技术为设计这种彩虹色薄膜的视觉外观开辟了新的可能性，从金属色到像素化或亚光纹理，为开发真正可持续的光子颜料在涂料、化妆品和安全标签中的应用铺平了道路。
