Chen Qi, Liu Ping, Nan Fuchun, Zhou Lijuan, Zhang Jianming
Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science & Technology , Qingdao City 266042, People's Republic of China.
Biomacromolecules. 2014 Nov 10;15(11):4343-50. doi: 10.1021/bm501355x. Epub 2014 Oct 21.
Iridescent films composed of the chiral nematic liquid crystal phase of cellulose nanocrystals (CNC) have attracted significant interest due to their fascinating optical properties. However, the current fabrication method, i.e., solution casting with a subsequent evaporation process, has significant limitations and therefore hinders the application of CNC iridescent films. In the present study, we demonstrate, for the first time, that vacuum-assisted self-assembly (VASA) can be used to fabricate highly oriented, large area, smooth, and structurally homogeneous CNC iridescent films. It was found that a long ultrasonic pretreatment is necessary for obtaining CNC iridescent films via VASA. Furthermore, it was also found that the iridescent color of the CNC films can be tuned by the sonication time, suspension volume, and degree of vacuum. By combining CD spectroscopy, SEM, and WAXD techniques, the internal structure of CNC iridescent films prepared by VASA has been investigated in detail. Moreover, the origin of the ultrasonic pretreatment effect on the self-assembly behavior of CNCs is also discussed.
由纤维素纳米晶体（CNC）的手性向列相液晶相组成的彩虹色薄膜因其迷人的光学特性而引起了广泛关注。然而，目前的制造方法，即溶液浇铸及随后的蒸发过程，存在显著局限性，因此阻碍了CNC彩虹色薄膜的应用。在本研究中，我们首次证明真空辅助自组装（VASA）可用于制备高度取向、大面积、光滑且结构均匀的CNC彩虹色薄膜。研究发现，通过VASA获得CNC彩虹色薄膜需要长时间的超声预处理。此外，还发现CNC薄膜的彩虹色可通过超声处理时间、悬浮液体积和真空度进行调节。通过结合圆二色光谱（CD）、扫描电子显微镜（SEM）和广角X射线衍射（WAXD）技术，对通过VASA制备的CNC彩虹色薄膜的内部结构进行了详细研究。此外，还讨论了超声预处理对CNC自组装行为产生影响的原因。
