Nanofibrillated cellulose (NFC) has garnered significant attention as a sustainable biomaterial, but its chemical reactivity with respect to its generation, i.e., fibrillation, has heretofore been unexplored. We prepared NFC samples with varying levels of fibrillation by controlling mechanical energy followed by acetylation as a probe to explore chemical reactivity. The degree of substitution (DS) reached a global maximum after which, surprisingly, it dropped to lower values at higher fibrillation or higher input (generation) energies. This behavior was attributed to two factors: the presence of higher bound water molecules at fibrillated surfaces, which hinder accessibility to cellulose chains, and enhanced self-aggregation of surface hydroxyl groups of NFC due to formation of hydrogen bonds at higher fibrillation. The discovery of these two mitigating factors provides a promising physicochemical strategy for efficient and sustainable production and modification of NFC to optimize performance for different applications.

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纤维素纳米原纤维的拓扑化学与机械生成能的关系

纳米原纤化纤维素（NFC）作为可持续的生物材料已经引起了广泛的关注，但是迄今为止，关于其产生即原纤化的化学反应性尚未得到开发。我们通过控制机械能，然后乙酰化作为探查化学反应性的探针，制备了具有不同原纤化水平的NFC样品。取代度（DS）达到了全局最大值，此后，令人惊讶的是，它在较高的原纤化或较高的输入（生成）能量下降至较低的值。该行为归因于两个因素：在原纤化的表面上存在较高结合的水分子，这阻碍了纤维素链的可及性；由于在较高的原纤化下形成了氢键，NFC表面羟基的自聚集增强了。