离子强度和表面电荷密度对纤维素纳米晶体薄膜膨胀动力学的影响,Langmuir

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离子强度和表面电荷密度对纤维素纳米晶体薄膜膨胀动力学的影响
Langmuir ( IF 3.7 ) Pub Date : 2017-07-21 00:00:00 , DOI: 10.1021/acs.langmuir.7b01740
Michael S. Reid ₁ , Stephanie A. Kedzior ₁ , Marco Villalobos ₂ , Emily D. Cranston ₁

Affiliation

这项工作通过研究离子强度（1–100 mM）不同的水溶液中的膜溶胀来探索纤维素纳米晶体（CNC）薄膜（<50 nm）和颗粒间的相互作用。通过表面等离振子共振原位监测CNC膜的水合作用，并定量吸收液体的动力学。通过使用具有不同表面电荷（阴离子硫酸盐半酯基团，高和低表面电荷密度和阳离子三甲基铵基团）的CNC，阐明了静电双层力对膜溶胀的贡献。发现薄膜中的总吸水量与离子强度和表面化学性质无关，这表明在聚集状态下范德华力在双层力上起主导作用，从而将薄膜固定在一起。但是，速度肿胀差异显着。吸水遵循Fickian行为，并且所测得的扩散常数随薄膜和溶液之间的离子强度梯度而降低。这项工作强调了纳米粒子的相互作用和分散在很大程度上取决于粒子的聚集状态，并且可以基于表面化学和溶液离子强度来调整聚集体和薄膜中的吸水率。

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Effect of Ionic Strength and Surface Charge Density on the Kinetics of Cellulose Nanocrystal Thin Film Swelling

This work explores cellulose nanocrystal (CNC) thin films (<50 nm) and particle–particle interactions by investigating film swelling in aqueous solutions with varying ionic strength (1–100 mM). CNC film hydration was monitored in situ via surface plasmon resonance, and the kinetics of liquid uptake were quantified. The contribution of electrostatic double-layer forces to film swelling was elucidated by using CNCs with different surface charges (anionic sulfate half ester groups, high and low surface charge density, and cationic trimethylammonium groups). Total water uptake in the thin films was found to be independent of ionic strength and surface chemistry, suggesting that in the aggregated state van der Waals forces dominate over double-layer forces to hold the films together. However, the rate of swelling varied significantly. The water uptake followed Fickian behavior, and the measured diffusion constants decreased with the ionic strength gradient between the film and the solution. This work highlights that nanoparticle interactions and dispersion are highly dependent on the state of particle aggregation and that the rate of water uptake in aggregates and thin films can be tailored based on surface chemistry and solution ionic strength.

更新日期：2017-07-22

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