Department of Electrical and Computer Engineering, University of Alberta, Edmonton, T6G 1H9, Canada; Department of Materials Science and Engineering, Indian Institute of Technology (IIT) Delhi, New Delhi, 11016, India.
Department of Electrical and Computer Engineering, University of Alberta, Edmonton, T6G 1H9, Canada.
Carbohydr Polym. 2020 Oct 15;246:116393. doi: 10.1016/j.carbpol.2020.116393. Epub 2020 May 4.
Cellulose nanocrystals (CNC) are the focus of significant attention in the broad area of sustainable technologies for possessing many desirable properties such as a large surface area, high strength and stiffness, outstanding colloidal stability, excellent biocompatibility and biodegradability, low weight and abundance in nature. Yet, a fundamental understanding of the micro- and nanoscale electrical charge distribution on nanocellulose still remains elusive. Here we present direct quantification and mapping of surface charges on CNCs at ambient condition using advanced surface probe microscopy techniques such as Kelvin probe force microscopy (KPFM), electrostatic force microscopy (EFM) and force-distance (F-D) curve measurements. We show by EFM measurements that the surface charge in the solid-state (as contrasted with liquid dispersions) present at ambient condition on CNCs provided by Innotech Alberta is intrinsically negative and the charge density is estimated to be 13 μC/cm. These charges also result in CNCs having two times the adhesive force exhibited by SiO substrates in adhesion mapping studies. The origin of negative surface charge is likely due to the formation of CNCs through sulfuric acid hydrolysis where sulfate half esters groups remained on the surface (Johnston et al., 2018).
纤维素纳米晶体(CNC)在可持续技术领域备受关注,因为它们具有许多理想的特性,如大的表面积、高强度和刚性、出色的胶体稳定性、优异的生物相容性和可生物降解性、低重量和丰富的天然来源。然而,对于纳米纤维素的微观和纳米尺度的电荷分布的基本理解仍然难以捉摸。在这里,我们使用先进的表面探针显微镜技术,如 Kelvin 探针力显微镜(KPFM)、静电力显微镜(EFM)和力-距离(F-D)曲线测量,在环境条件下直接定量和绘制 CNC 表面电荷的分布。我们通过 EFM 测量表明,在环境条件下,艾纳特科技 Alberta 公司提供的固态 CNC 表面存在固有负电荷,电荷密度估计为 13 μC/cm。这些电荷还导致 CNC 在粘附映射研究中表现出比 SiO 衬底高两倍的粘附力。负表面电荷的产生可能是由于 CNC 是通过硫酸水解形成的,硫酸半酯基团留在表面上(Johnston 等人,2018 年)。
Biomacromolecules. 2013-8-16
Chem Commun (Camb). 2014-11-7
Carbohydr Polym. 2013-2-28
Philos Trans A Math Phys Eng Sci. 2018-2-13
Nat Nanotechnol. 2012-2-26
Langmuir. 2010-3-16
Int J Biol Macromol. 2017-8-31
Micromachines (Basel). 2021-11-27
J Nanobiotechnology. 2020-11-12