Although it is difficult to deduce anything in this temperature range from our thermograms, peaks are clearly apparent in the DSC plots of the derivative weight percent loss per degrees Celsius versus the temperature (Figure 4). Figure 4 shows clear peaks in the temperature range of 580°C to 650°C and may indicate iron oxide contamination in the samples. We plotted the intensity of these DSC peaks versus increasing chain length (Figure 5) and at 60-min reflux times, we found a very linear correlation
between increasing chain length and increasing iron oxide contamination (R 2 = 0.996). This linear correlation is not present with 30-min reflux times. This suggests that shorter reflux times reduce the amount of iron oxide contamination in the samples. Taken together with the TEM images and size analysis, this again see more indicates to us that the shorter chain fatty amine (TDA) is more efficient at making less polydispersed and pure (lower iron oxide contamination) SIPPs. Figure 3 TGA thermograms of SIPPs and fatty amines. TGA thermograms of the SIPPs synthesized using ODA (A), HDA (B), TDA (C), and DDA (D). Dotted line = ligand only, black line = 30-min reflux, mTOR inhibitor and gray line = 60-min reflux. The weight percent of ligands and naked alloy, as well as quantification of the number of bound ligands, is listed in Table 1. Figure 4 DSC curves of SIPPs and fatty
amines. DSC curves for the SIPPs synthesized using ODA (A), HDA (B), TDA (C), and DDA (D). Dotted line = ligand only, black line = 30-min reflux, and gray line = 60-min reflux. Figure 5 Plot of DSC peak at approximately 600°C versus chain length. Plot of the derivative weight percent per degrees Celsius for the iron oxide peak (approximately
580°C to 650°C) versus chain length. Diamond = solid line = 30-min reflux (R 2 = 0.731). Square = dashed line = 60-min reflux (R 2 = 0.996). We next used ICP-OES to quantify the amount of iron and platinum in each of the samples. Moreover, we used this data to calculate the iron/platinum stoichiometry as well as the atomic percent of iron and platinum. The measured amounts of iron and platinum are listed GNE-0877 in Table 1. It is evident that, in general, we saw increasing iron and platinum concentrations with increasing chain length. Also, except for the SIPPs synthesized with HDA, the atomic percent iron was fairly stable at approximately 50% regardless of the fatty amine used. Using the data generated thus far, we also calculated the particle volume, surface area, number of nanoparticles per milliliter of suspension, suspension concentration, and mass per particle to comprehensively characterize the structural properties of the samples. All of the structural characterizations are listed in Table 1. Stability is also an important factor in nanoparticle synthesis.