Zhang Dejian, Fang Zhiqiang, Hu Shuiqing, Qiu Xueqing
State Key Laboratory of Pulp and Paper Engineering, School of Light Industry and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510640, PR China.
State Key Laboratory of Pulp and Paper Engineering, School of Light Industry and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510640, PR China.
Carbohydr Polym. 2024 Dec 15;346:122630. doi: 10.1016/j.carbpol.2024.122630. Epub 2024 Aug 22.
Cellulose nanofibril (CNF) films with both high strength and high toughness are attractive for applications in energy, packaging, and flexible electronics. However, simultaneously achieving these mechanical properties remains a significant challenge. Herein, a multiscale structural optimization strategy is proposed to prepare high aspect ratio CNFs with reduced crystallinity for strong and tough films. Carboxymethylation coupled with mild mechanical disintegration is employed to modulate the multiscale structure of CNFs. The as-prepared CNFs feature an aspect ratio of >800 and a crystallinity of <60 %. The film prepared using CNFs with a high aspect ratio (1100) and reduced crystallinity (54 %) exhibits a tensile strength of 229.9 ± 9.9 MPa and toughness of 22.2 ± 1.4 MJ/m. The underlying mechanism for balancing these mechanical properties is unveiled. The high aspect ratio of the CNFs facilitates the transfer and distribution of local stress, thus endowing the corresponding film with high strength and toughness. Moreover, the low crystallinity of the CNFs permits the movement of the cellulose chains in the amorphous regions, thereby dissipating energy and finally increasing the film toughness. This work introduces an innovative and straightforward method for producing strong and tough CNF films, paving the way for their broader applications.
具有高强度和高韧性的纤维素纳米原纤（CNF）薄膜在能源、包装和柔性电子领域的应用中具有吸引力。然而，同时实现这些机械性能仍然是一项重大挑战。在此，提出了一种多尺度结构优化策略，以制备具有降低结晶度的高长径比CNF，用于制备坚固且坚韧的薄膜。采用羧甲基化结合温和的机械解纤来调节CNF的多尺度结构。所制备的CNF的长径比>800，结晶度<60%。使用高长径比（1100）和降低结晶度（54%）的CNF制备的薄膜表现出229.9±9.9MPa的拉伸强度和22.2±1.4MJ/m的韧性。揭示了平衡这些机械性能的潜在机制。CNF的高长径比促进了局部应力的传递和分布，从而赋予相应薄膜高强度和韧性。此外，CNF的低结晶度允许纤维素链在非晶区移动，从而耗散能量并最终提高薄膜韧性。这项工作介绍了一种创新且直接的方法来生产坚固且坚韧的CNF薄膜，为其更广泛的应用铺平了道路。
