CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , No. 11 ZhongguancunBeiyitiao, Beijing 100190, China.
School of Sciences and Research Center for Advanced Computation, Xihua University , No. 999 JingniuquJingzhoulu, Chengdu 610039, China.
Langmuir. 2017 Sep 5;33(35):8724-8729. doi: 10.1021/acs.langmuir.7b00923. Epub 2017 May 9.
In situ analysis and study on the surface of nanoparticles (NPs) is a key to obtain their important physicochemical properties for the subsequent applications. Of them, most works focus on the qualitative characterization whereas quantitative analysis and measurement on the NPs under their storage and usage conditions is still a challenge. In order to cope with this challenge, solvation relaxation-based nuclear magnetic resonance (NMR) technology has been applied to measure the wet specific surface area and, therefore, determine the number of the bound water molecules on the surface of silica NPs in solution and the hydrophilic groups of various types grafted on the surface of the NPs. By changing the surface functional group on silica particles, the fine distinction for the solvent-particle interaction with different surface group can be quantitatively differentiated by measuring the number of water molecules absorbed on the surface. The results show that the number of the surface hydroxyl, amine, and carboxyl group per nm is 4.0, 3.7, and 2.3, respectively, for the silica particles with a diameter of 203 nm. The method reported here is the first attempt to determine in situ the number of bound solvent molecules and any solvophilic groups grafted on nanoparticles.
对纳米粒子（NPs）表面进行原位分析和研究是获得其后续应用的重要物理化学性质的关键。其中，大多数工作都集中在定性表征上，而对 NPs 在储存和使用条件下的定量分析和测量仍然是一个挑战。为了应对这一挑战，基于溶剂化松弛的核磁共振（NMR）技术已被应用于测量湿比表面积，从而确定溶液中二氧化硅 NPs 表面上结合的水分子数量以及接枝在 NPs 表面上的各种类型的亲水性基团。通过改变二氧化硅颗粒表面的官能团，可以通过测量表面上吸收的水分子数量，对具有不同表面基团的溶剂-颗粒相互作用进行精细区分。结果表明，对于直径为 203nm 的二氧化硅颗粒，表面羟基、胺基和羧基的数量分别为每纳米 4.0、3.7 和 2.3。这里报道的方法是首次尝试原位确定结合溶剂分子的数量和接枝在纳米颗粒上的任何亲溶剂基团。
