Es had been estimated making use of a model for the calculation of your particle film growth rate based on the thermo phoretic velocity previously created [52,53] and located to become one hundred 25 nm for Sample #1 and 200 25 nm for Sample #2. Within this study, the process and the total sampling times were chosen to create thick nanoparticle films covering the complete substrate, so avoiding any interaction be tween the AFM tip along with the mica muscovite substrate that could influence the nanoindentation measurement of the samples. Furthermore, for PEN, HOPG and soot particle films the location indented by an indenter of 5000 nm radius may be regarded as as a semiinfinite space and so the hardness and Young’s modulus values might be assumed to become correct. Around the other hand, this can be not feasible to get a single particle having a dimension in the identical order of magnitude of the tip radius, or perhaps decrease [21]. Furthermore, the imaging of a nanoindent performed on a single nanoparticle is pretty hard to perform. It really is worth underlining that nanoindentation Hexestrol MedChemExpress measurements on single soot particles have been performed and re ported, but for the reasons listed above they couldn’t be taken with full self-confidence on an absolute scale [21].Appl. Sci. 2021, 11,7 ofFigure four reports common force istance curves measured on Sample #1 and on Sample #2. It is attainable to observe that at a provided deformation the UCL 1684 dibromide Autophagy maximum load applied to Sample #2 is higher than that of Sample #1. The adhesion forces measured for both sam ples are within the order of 0.two 0.01 N.Figure 4. Force istance curves measured through method (green line) and retract (red line) on Sample #1 (a) and on Sample #2 (b).Figures five and 6 show semicontact AFM pictures of an indent on Sample #1 surface (Figure 5a) and Sample #2 surface (Figure 6a), too because the very same images analyzed with the Gwyddion software and marked with a red mask used to calculate the projected area (Figures 5b and 6b). The projected regions of the intend resulted in AP 10000 500 nm2 for Sample #1 and AP 11000 500 nm2 for Sample #2.Figure 5. Semicontact AFM image of an indent on Sample #1 surface (a); identical image as in the upper panel after cropping and analysis with the software Gwyddion (b).Appl. Sci. 2021, 11,8 ofFigure six. Semicontact AFM image of an indent on Sample #2 surface (a); same image as inside the upper panel soon after cropping and analysis with the software program Gwyddion (b).The results of nanoindentation measurements are reported in Table 2. The mean val ues of hardness measured in the maximum load and also the intend area have been H = 0.75 0.05 GPa for Sample #1 and H = 0.9 0.05 GPa for Sample #2. The evaluation on the retraction curves with all the DMT match model reported a mean Young’s modulus E = four.2 0.three GPa for Sample #1 and E = 7.2 0.4 GPa for Sample #2. Exactly the same Poisson ratiosample = 0.3 as for HOPG was used.Table 2. Hardness and Young’s modulus measured by AFM nanoindentation on Sample #1 and Sample #2 and in comparison to PEN and HOPG. Errors are reported because the imply common deviation from 20 independent measurements.Sample Sample #1 Sample #2 PEN HOPGHardness H, GPa 0.75 0.05 0.90 0.05 0.70 0.05 two.40 0.Young’s Modulus E, GPa four.two 0.3 7.2 0.four three.eight 0.3 7.5 0.Each Sample #1 and Sample #2 films showed decrease hardness and Young’s modulus in comparison with HOPG. This may be explained looking at the structure of particle films. Soot nanostructured films are composed by nanoscale grains which may be thought of because the fundamental.
