硒化镉
表面改性
量子点
乙二醇
分散稳定性
配体(生物化学)
色散(光学)
化学
化学工程
纳米颗粒
高分子化学
材料科学
纳米技术
光化学
有机化学
物理化学
光学
物理
受体
工程类
生物化学
作者
Whitney Wenger,Frank S. Bates,Eray S. Aydil
出处
期刊:Langmuir
[American Chemical Society]
日期:2017-08-10
卷期号:33 (33): 8239-8245
被引量:31
标识
DOI:10.1021/acs.langmuir.7b01924
摘要
Semiconductor quantum dots synthesized using rapid mixing of precursors by injection into a hot solution of solvents and surfactants have surface ligands that sterically stabilize the dispersions in nonpolar solvents. Often, these ligands are exchanged to disperse the quantum dots in polar solvents, but quantitative studies of quantum dot surfaces before and after ligand exchange are scarce. We studied exchanging trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO) ligands on as-synthesized CdSe quantum dots dispersed in hexane with a 2000 g/mol thiolated poly(ethylene glycol) (PEG) polymer. Using infrared spectroscopy we quantify the absolute surface concentration of TOP/TOPO and PEG ligands per unit area before and after ligand exchange. While 50-85% of the TOP/TOPO ligands are removed upon ligand exchange, only a few are replaced with PEG. Surprisingly, the remaining TOP/TOPO ligands outnumber the PEG ligands, but these few PEG ligands are sufficient to disperse the quantum dots in polar solvents such as chloroform, tetrahydrofuran, and water. Moreover, as-synthesized quantum dots once easily dispersed in hexane are no longer dispersible in nonpolar solvents after ligand exchange. A subtle coverage-dependent balance between attractive PEG-solvent interactions and repulsive TOP/TOPO-solvent interactions determines the dispersion stability.
科研通智能强力驱动
Strongly Powered by AbleSci AI