Analysis of Binary and ternary mixtures of lipids and  high-throughput generation of monolayers on 2-D crystalline surfaces

From applications in nanoscale electronics to regenerative medicine, there is a strong need for control assembly processes at nanometer length scales.1,2 In this work, we investigate the application of microscale droplet delivery as a rapid and scalable approach to pattern the molecular assembly of nanoscale chemical patterns on highly oriented pyrolytic graphite (HOPG). Furthermore, it was also observed that variations in the blend of alkyl impurities present in technical-grade OLAm reagents influenced the temperature-dependent assembly behavior.13 This suggests a likely role of alkyl chain phase transitions in the ligand shell, particularly in more complex mixtures and for anisotropic nanocrystals.

Oleylamine (OLAm) is a common technical-grade reagent used in nanocrystal synthesis. Most nanocrystal synthesis is done using technical grade Oleylamine (70% purity). Higher purity reagents are not readily available because in certain instances, technical grades are obtained from natural substances, resulting in differing impurities compared to those generated during preparative reactions using pure raw materials.3 Technical grade reagents of OLAm contain 70% of the cis chain OLAm and 30% of an unspecified mixture of Elaidylamine (ELAm) , Octadecylamine (ODAm) and segments of various lengths and saturated alkyl chains.4,5 Here, we use Differential Scanning Calorimetry thermograms to investigate the miscibility of binary mixtures of OLAm/ELAm, OLAm/ODAm, and ELAm/ODAm. Ternary mixtures of the lipids showed clear peaks for the trans and saturated impurities.

We patterned graphite surfaces with amphiphiles via inkjet printing to quickly generate 1-nm-wide functional patterns. Inkjet printing allowed for long-scale hierarchical patterning. We investigated various ink formulations and the resulting printing quality of functional monolayers on 2D crystalline materials.