School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province, 225002, PR China.
School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province, 225002, PR China; Institution of Innovative Materials & Energy, Yangzhou, Jiangsu Province, 225002, PR China.
Carbohydr Polym. 2021 Mar 1;255:117483. doi: 10.1016/j.carbpol.2020.117483. Epub 2020 Dec 5.
Three types of nanocelluloses, including bacterial cellulose (BC), cellulose nanofiber (CNF) and cellulose nanocrystal (CNC), were used to prepare oil-in-water Pickering emulsions with the objective to disclose the effect of fiber flexibility on emulsification. In aqueous suspensions, the shortest CNC is rigid, while the longest BC fully flexible, which result in large difference in their dilute-to-semi-dilute concentrations, and in the rheological percolations. Thus, these cellulosic nanofibers play different roles during emulsification. Flexible BC nearly has no emulsifying capacity, whereas semi-flexible CNF and rigid CNC can be well used to stabilize emulsions. For the CNF-stabilized system, depletion effect is dominant, leading to the formation of droplet clusters easily, while for the CNC-stabilized one, repulsive effect plays more important role. Visible evidence regarding relaxation of long-term structure of droplets is further disclosed by dynamic rheology. This work proposes interesting views around tailoring morphology and viscoelasticity of Pickering emulsions by regulating fiber flexibility.
三种纳米纤维素，包括细菌纤维素（BC）、纤维素纳米纤维（CNF）和纤维素纳米晶体（CNC），被用于制备油包水 Pickering 乳液，旨在揭示纤维柔韧性对乳化的影响。在水悬浮液中，最短的 CNC 是刚性的，而最长的 BC 则是完全柔性的，这导致它们在稀至半稀浓度以及流变学渗滤方面存在很大差异。因此，这些纤维素纳米纤维在乳化过程中发挥不同的作用。柔性的 BC 几乎没有乳化能力，而半柔性的 CNF 和刚性的 CNC 可以很好地用于稳定乳液。对于 CNF 稳定的体系，耗尽效应占主导地位，容易导致液滴团聚的形成，而对于 CNC 稳定的体系，排斥效应则起着更重要的作用。通过动态流变学进一步揭示了关于液滴长期结构松弛的可见证据。这项工作提出了通过调节纤维柔韧性来定制 Pickering 乳液形态和粘弹性的有趣观点。
