State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, P. R. China.
School of Advanced Manufacturing and Mechanical Engineering, University of South Australia , Adelaide, South Australia 5095, Australia.
ACS Appl Mater Interfaces. 2017 May 31;9(21):18231-18237. doi: 10.1021/acsami.7b04590. Epub 2017 May 16.
Cellulose nanocrystals (CNCs) have attracted much interest due to their unique optical property, rich resource, environment friendliness, and templating potentials. CNCs have been reported as novel photonic humidity sensors, which are unfortunately limited by the dissolution and unideal moisture absorption of CNCs. We, in this study, developed a high-performance photonic humidity composite sensor that consisted of CNCs and polyacrylamide; chemical bonding was induced between the two components by using glutaraldehyde as a bridging agent. The composites inherited the chiral nematic structure of CNCs and maintained it well through a cycling test. A distinct color change was observed for these composites used as a humidity indicator; the change was caused by polyacrylamide swelling with water and thus enlarging the helical pitch of the chiral nematic structure. The composites showed no degradation of the sensing performance through cycling. The excellent cycling stability was attributed to the bonding between polyacrylamide and CNCs. This composite strategy can extend to the development of other photonic indicators.
纤维素纳米晶体（CNCs）因其独特的光学性质、丰富的资源、环境友好性和模板潜力而引起了广泛的关注。CNCs 已被报道为新型光子湿度传感器，但不幸的是，其受到 CNCs 的溶解和不理想的吸湿性能的限制。在本研究中，我们开发了一种由 CNCs 和聚丙烯酰胺组成的高性能光子湿度复合传感器；通过使用戊二醛作为桥联剂，在两种组分之间诱导化学结合。该复合材料继承了 CNCs 的手性向列结构，并通过循环测试很好地保持了其结构。这些用作湿度指示剂的复合材料表现出明显的颜色变化；这种变化是由聚丙烯酰胺吸水膨胀并因此扩大手性向列结构的螺旋间距引起的。复合材料在循环过程中没有表现出传感性能的降解。优异的循环稳定性归因于聚丙烯酰胺和 CNCs 之间的键合。这种复合策略可以扩展到其他光子指示剂的开发。
