Zhang Fusheng, Ge Wenna, Wang Cunli, Zheng Xintong, Wang Dongdong, Zhang Xiancheng, Wang Xue, Xue Xingya, Qing Guangyan
CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China.
University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
ACS Appl Mater Interfaces. 2021 Apr 14;13(14):17118-17128. doi: 10.1021/acsami.1c02753. Epub 2021 Apr 1.
Cellulose nanocrystals (CNCs) are powerful photonic building blocks for the fabrication of biosourced colored films. A combination of the advantages of self-assembled CNCs and multiple templating agents offers access to the development of novel physicochemical sensors, structural coatings, and optic devices. However, due to the inherent brittleness and water instability of CNC-derived materials, their further applications are widely questionable and restrictive. Here, a soft polymer of poly(vinyl alcohol) (PVA) was introduced into the rigid CNC system to balance molecular interactions, whereafter two hard/soft nanocomposites were fastened through a cross-linking reaction of glutaraldehyde (GA), resulting in a highly flexible, water-stable, and chiral nematic CNC composite film through an evaporation-induced self-assembly technique. For a 1.5 wt % GA-cross-linked 70 wt % CNC loading film, its treatment with harsh hydrophilic exposure (soaking in a strong acid, strong base, and seawater) and various organic solvents show exceptional solvent-resistant abilities. Furthermore, the film can even withstand a weight of 167 g cm without failure, which is a highly stiff and durable character. Importantly, the film remains a highly ordered chiral nematic organization, being able to act as a highly transparent substrate for selective reflection of left-handed circularly polarized light, preparing fully covered and patterned full-color coatings on various substrates. Our work paves the way for applications in low-cost, durable, and photonic cellulosic coatings.
纤维素纳米晶体（CNCs）是用于制造生物源彩色薄膜的强大光子构建块。自组装CNCs的优势与多种模板剂相结合，为新型物理化学传感器、结构涂层和光学器件的开发提供了途径。然而，由于CNC衍生材料固有的脆性和水不稳定性，它们的进一步应用受到广泛质疑和限制。在此，将聚乙烯醇（PVA）这种软聚合物引入刚性CNC系统以平衡分子间相互作用，然后通过戊二醛（GA）的交联反应将两种硬/软纳米复合材料固定在一起，通过蒸发诱导自组装技术得到了一种高度柔性、水稳定且具有手性向列相的CNC复合薄膜。对于1.5 wt% GA交联、70 wt% CNC负载的薄膜，其在苛刻的亲水性暴露条件下（浸泡在强酸、强碱和海水中）以及各种有机溶剂中的处理表现出卓越的耐溶剂能力。此外，该薄膜甚至能够承受167 g/cm的重量而不破裂，这是一种高度坚硬且耐用的特性。重要的是，该薄膜保持高度有序的手性向列相结构，能够作为选择性反射左旋圆偏振光的高透明基板，在各种基板上制备完全覆盖且有图案的全彩色涂层。我们的工作为低成本、耐用且具有光子特性的纤维素涂层的应用铺平了道路。
