Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A*STAR), 2 Fusionopolis Way, Innovis, Singapore 138634, Singapore; Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore.
Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore.
J Colloid Interface Sci. 2023 Apr;635:197-207. doi: 10.1016/j.jcis.2022.12.109. Epub 2022 Dec 21.
Underwater oil-repellency of polyelectrolyte brushes has been attributed mainly to electric double-layer repulsion forces based on Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Many non-polyelectrolyte materials also exhibit oil-repellent behaviour, but it is not clear if there exist similar electric double-layer repulsion and if it is the sole mechanism governing their underwater oil-repellency.
EXPERIMENTS/SIMULATIONS: In this article, the oil-repellency of highly amorphous cellulose exhibiting is investigated in detail, through experiments and molecular dynamics simulations (MDS).
It was found that the stable surface hydration on regenerated cellulose was due to a combination of long-range electrostatic repulsions (DLVO theory) and short-range interfacial hydrogen bonding between cellulose and water molecules (as revealed by MDS). The presence of a stable water layer of about 200 nm thick (similar to that of polyelectrolyte brushes) was confirmed. Such stable surface hydration effectively separates cellulose surface from oil droplets, resulting in extremely low adhesion between them. As a demonstration of its practicality, regenerated cellulose membranes were fabricated via electrospinning, and they exhibit high oil/water separation efficiencies (including oil-in-water emulsions) as well as self-cleaning ability.
基于德贾金-朗道-范德瓦尔斯（DLVO）理论，聚电解质刷的水下拒油性主要归因于双电层排斥力。许多非聚电解质材料也表现出拒油行为，但尚不清楚是否存在类似的双电层排斥力，以及它是否是控制其水下拒油性的唯一机制。
实验/模拟：在本文中，通过实验和分子动力学模拟（MDS）详细研究了具有高非晶度的纤维素的拒油性。
发现再生纤维素表面的稳定水合作用是由于长程静电排斥（DLVO 理论）和纤维素与水分子之间的短程界面氢键的共同作用（通过 MDS 揭示）。证实了约 200nm 厚的稳定水层的存在（类似于聚电解质刷）。这种稳定的表面水合作用有效地将纤维素表面与油滴隔开，从而导致它们之间的极低粘附力。作为其实用性的证明，通过静电纺丝制造了再生纤维素膜，它们表现出高的油水分离效率（包括水包油乳液）以及自清洁能力。
