Size separations of silver nanoparticles using

• Main Authors: Chen, Wan-Ru, 陳琬茹
• Other Authors: Yu, Tiing
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/04749564565645779256

碩士 === 國立交通大學 === 應用化學系所 === 97 === The purpose of this study is size-separation of silver nanoparticles (AgNPs) using aqueous two-phase systems (ATPS). Polyethylene glycol (PEG) and K2HPO4 were selected to formulate the ATPS. By modifying the ATPS compositions, we could manipulate the partition coefficients of different size AgNPs in the two aqueous phases. The parameters modified in our study included the molecular weight of PEG, the salt concentration, the polymer concentration and the urea addition to the system. The optimum ATPS was 15% (w/w) PEG (M.W.6000) with 10% (w/w) K2HPO4. This solvent system was applied to extract the AgNPs in which the surface was modified by 11-mercaptoundecanoic acid (MUA). The size distributions of AgNPs in both phases were measured by Scanning Electron Microscopy. The partition of AgNPs with larger size was favored to enter the upper phase, i.e. PEG-rich phase, while the smaller AgNPs would exist in the bottom phase, i.e. K2HPO4-rich iv phase. Hydrophobic interaction between the MUA and PEG molecules was considered the major force on the AgNPs partitioning. Three-step batch extractions were then performed to examine the separation efficiency. The average sizes of AgNPs in the first step extraction were 11.5 ± 1.9 nm in the upper phase and 10.5 ± 1.8 nm in the bottom phase. The AgNPs sizes in the second extraction were 13.0 ± 1.9 nm in the upper phase and 11.0 ± 2.1 nm in the bottom phase. The sizes in the last extraction were 13.1 ± 2.1 nm in the upper phase and 11.1 ± 2.4 nm in the bottom phase. The results showed the partition of AgNPs was size-dependent; therefore the size separation of AgNPs could be successfully performed using ATPS extractions.