Li Zongzhe, Wang Phoebe, Zhang Yinghao, Michal Carl A, MacLachlan Mark J
Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
Department of Physics and Astronomy, The University of British Columbia, 6224 Agricultural Rd., Vancouver, BC, V6T 1Z1, Canada.
Small. 2025 Feb;21(6):e2409701. doi: 10.1002/smll.202409701. Epub 2024 Dec 24.
Cellulose nanocrystals (CNCs) are known to self-assemble into a left-handed chiral nematic lyotropic liquid crystalline phase in water. When captured in the solid state, this structure can impart films with photonic properties that make them promising candidates in photonics, sensing, security, and other areas. Unfortunately, the intrinsic hydrophilicity of CNCs renders these iridescent films susceptible to moisture, thereby limiting their practicality. To address this issue, a novel strategy to prepare hydrophobic iridescent films from pre-assembled CNC films is reported here. These films underwent a swelling process, followed by esterification using acid anhydrides to render them hydrophobic. By increasing the alkyl chain length of the anhydride reagent, the hydrophobicity of the resulting iridescent films can be enhanced. They showed water contact angles ranging from 34° to 115° and demonstrated tunable structural color spanning from blue to red. Moreover, they also exhibited good durability when exposed to water for 24 h. This innovative method for producing durable hydrophobic iridescent thin films is expected to facilitate their use in water-proof photonic coatings, optical sensors, and other applications.
众所周知，纤维素纳米晶体（CNCs）在水中会自组装成左旋手性向列型溶致液晶相。当以固态捕获时，这种结构可以赋予薄膜光子特性，使其成为光子学、传感、安全和其他领域有前景的候选材料。不幸的是，CNCs固有的亲水性使这些彩虹色薄膜易受潮，从而限制了它们的实用性。为了解决这个问题，本文报道了一种从预组装的CNC薄膜制备疏水性彩虹色薄膜的新策略。这些薄膜经历了溶胀过程，然后使用酸酐进行酯化以使其具有疏水性。通过增加酸酐试剂的烷基链长度，可以提高所得彩虹色薄膜的疏水性。它们的水接触角范围为34°至115°，并展示了从蓝色到红色的可调结构颜色。此外，当暴露于水中24小时时，它们还表现出良好的耐久性。这种生产耐用疏水性彩虹色薄膜的创新方法有望促进其在防水光子涂层、光学传感器和其他应用中的使用。
