The use of cellulose has considerable promise in a wide range of industrial applications but is hampered by degradation in mechanical properties due to ambient moisture uptake. Existing models of equilibrium moisture content can predict the impact of these effects, but at present, the dynamical, atomic-scale picture of water ingress into cellulose is lacking. The present work reports nonequilibrium molecular simulations of the interface between cellulose and water aimed at capturing the initial stages of two simultaneous dynamical processes, water ingress into cellulose and cellulose dissolution into water. These simulations demonstrate that the process depends on the temperature and chain length in the amorphous region, where high temperatures can induce more mass exchange and short chains can easily detach from amorphous cellulose. A cooperative mechanism that involves both chemical and physical aspects, namely, hydrogen bonding and chain intertwining, respectively, is proposed to interpret the incipient dual ingress/dissolution process. Outcomes of this work will provide a foundation for cellulose functionalization strategies to impede moisture uptake and preserve the mechanical properties of nanocellulose in applications.

中文翻译：

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非晶-结晶纤维素界面的动态进水和溶解

纤维素的使用在广泛的工业应用中具有相当大的前景，但由于环境水分吸收而受到机械性能退化的阻碍。现有的平衡水分含量模型可以预测这些影响的影响，但目前缺乏水分进入纤维素的动态、原子级图片。目前的工作报告了纤维素和水之间界面的非平衡分子模拟，旨在捕捉两个同时发生的动力学过程的初始阶段，水进入纤维素和纤维素溶解到水中。这些模拟表明，该过程取决于无定形区域的温度和链长，其中高温可以引起更多的质量交换，而短链很容易从无定形纤维素上分离。提出了一种涉及化学和物理方面的合作机制，即分别是氢键和链缠绕，以解释初始的双重进入/溶解过程。这项工作的结果将为纤维素功能化策略提供基础，以阻止水分吸收并在应用中保持纳米纤维素的机械性能。