Brittleness has hindered commercialization of cellulose nanofibril (CNF) films. The use of synthetic polymers and plasticizers is a known detour that impairs biodegradability and carbon footprint of the product. Herein, we utilize a variety of softwood Kraft lignin morphologies to obtain strong and ductile CNF nanocomposite films. An optimum 10 wt % content of colloidal lignin particles (CLPs) produced films with nearly double the toughness compared to a CNF film without lignin. CLPs rendered the films waterproof, provided antioxidant activity and UV-shielding with better visible light transmittance than obtained with irregular lignin aggregates. We conclude based on electron microscopy, dynamic water sorption analysis, and tp-DSC that homogeneously distributed CLPs act as ball bearing lubricating and stress transferring agents in the CNF matrix. Overall, our results open new avenues for the utilization of lignin nanoparticles in biopolymer composites equipped with versatile functionalities for applications in food packaging, water purification, and biomedicine.

中文翻译：

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具有胶态木质素颗粒的强力，韧性和防水纤维素纳米原纤维复合膜。

脆性阻碍了纤维素纳米原纤维（CNF）薄膜的商业化。合成聚合物和增塑剂的使用是已知的绕道，其损害了产品的生物降解性和碳足迹。在本文中，我们利用各种软木牛皮纸木质素形态来获得结实而易延展的CNF纳米复合膜。与不含木质素的CNF薄膜相比，胶体木质素颗粒（CLP）的最佳10 wt％含量可生产出具有几乎两倍韧性的薄膜。CLP使薄膜具有防水性，与不规则木质素聚集体相比，具有抗氧化活性和紫外线屏蔽性能，并且具有更好的可见光透射率。我们基于电子显微镜，动态吸水分析和tp-DSC得出结论，均匀分布的CLP在CNF基质中充当滚珠轴承的润滑和应力传递剂。