The Trouble with 1-Octadecene; Polymerization During Nanocrystal Synthesis

09 July 2019, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

1-octadecene is a widely used solvent for high temperature nanocrystal synthesis (120 – 320 °C). Here, we show that 1-octadecene spontaneously polymerizes under these conditions and the resulting poly(1-octadecene) has a comparable solubility and size to nanocrystals stabilized by hydrophobic ligands. Typical purification procedures (precipitation/redispersion cycles or size exclusion chromatography) fail to separate the poly(1-octadecene) impurity from the nanocrystal product. To avoid formation of poly(1-octadecene), we replaced 1-octadecene with saturated, aliphatic solvents. Alternatively, the native ligands are exchanged for polar ligands, leading to significant solubility differences between nanocrystals and poly(1-octadecene), therefore allowing isolation of pure nanocrystals, free from polymer impurities. These results will help design superior syntheses and improve nanocrystal purity, an important factor in many applications.

Keywords

surface chemistry
ligand chemistry
nanomaterials
nanoparticles
Hot Injection Synthesis
heating up synthesis
quantum dots
zinc sulfide
titanium oxide
iron oxide
cadmium sulfide
Copper Indium Sulfide

Supplementary materials

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