Wood-inspired strategy to toughen transparent cellulose nanofibril films

• Published in: Carbohydrate polymers 2021-05, Vol.259, p.117759-117759, Article 117759
• Main Authors: Zhou, Jie, Fang, Zhiqiang, Cui, Jinyi, Zhang, Xiao, Qian, Yong, Liu, Weifeng, Yang, Dongjie, Qiu, Xueqing
• Format: Article
• Language: English
• Subjects: Cellulose nanofibril film; Lignosulfonic acid; Toughness; Transparency; Wood-inspired strategy
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2021.117759

•The adsorption performance of lignosulfonate acid (LA) on cellulose nanofibers (CNF) is better than sodium lignosulphonate (LS).•The mechanical properties of CNF/LA nanocomposite films reached the advanced level of CNF based films compared to previous literature.•The underlying toughening mechanism of the resulting CNF/LA nanocomposite films was investigated in detail.•The CNF/LA nanocomposite films also have UV absorption performance, good thermo-oxygen aging resistance, and better water resistance. The simultaneous attainment of high strength and high toughness of transparent cellulose nanofibril (CNF) film can expedite its uses in advanced applications. In this work, a wood-inspired strategy is proposed to address the conflict between strength and toughness by using natural derived lignosulfonic acid (LA) as a reinforcing additive. Only 1 wt% LA addition can double the toughness (11.0±1.3 MJ/m3) of pure CNF film. Consequently, the as-prepared CNF/LA-1 nanocomposite film not only exhibits superior mechanical properties (23.6±1.3 MJ/m3 toughness, 249±6 MPa strength, and 15.4±1.4 % strain), but also maintains an excellent optical transparency of 91.2 % (550 nm). Furthermore, the mechanism for simultaneously enhancing strength and toughness is essentially attributed to the improved hydrogen bonding between CNF-OH and LA-SO3H and effective energy dissipation system. This work provides a green and effective approach to prepare strong yet tough and transparent biodegradable CNF film for high-end applications.