Properties of reference supplies. PEN substates had been chosen as a medium soft material. Figure 2a shows a semicontact AFM image of an indent brought on for the duration of in dentation measurements by the tip around the PEN surface. Figure 2b shows precisely the same image cropped and analyzed using the Gwyddion software, where the indent was overlaid with a red mask used to calculate the projected area. The imply value of projected area on the intend resulted AP 14000 500 nm2.Figure 2. Semicontact AFM image of an indent on PEN surface (a); same image as within the upper panel following cropping and analysis with the computer software Gwyddion (b).From several force istance curves acquired on Propamocarb MedChemExpress unique places from the sample and using a Poisson ratio sample = 0.3 [47], the mean mechanical properties of PEN were meas ured to be equal to H = 0.70 0.05 GPa and E = three.8 0.3 GPa, in pretty superior agreement with values reported within the literature [48]. HOPG is often a higher purity graphitic structure and can be thought of as a reference within the evaluation from the properties of soot particles. Figure 3 shows a semicontact AFM image of an indent on the HOPG surface (Figure 3a) and also the same image cropped and analyzed using the Gwyddion software program (Figure 3b). The hardness measured on HOPG samples by AFM in the imply projected location, AP 18000 700 nm2, was located H = two.40 0.ten GPa. This value is in great agreement with previously reported measurements performed onAppl. Sci. 2021, 11,six ofHOPG [21,44,49]. Alternatively, the evaluation in the retraction curves with the DMT model employing a Poisson ratio sample = 0.two [44] resulted in an underestimation on the Young’s modulus. The imply measured by Young’s modulus was E = 7.5 0.3 GPa, drastically reduced than the reported values E = 150 GPa [44,50]. This difference is possibly because of the experi mental setup. The tip employed within this study is characterized by a spring constant which has proved to be suitable for measuring the elastic modulus, at the same time as the hardness, on me diumsoft samples (E 10 GPa). However, the spring continuous on the cantilever is most Hexestrol References likely also low to effectively perform an elastic deformation at smaller indentation depths on a mediumhard sample for example HOPG (E 10 GPa), as a result affecting the accuracy on the calculation of the Young’s modulus from the retraction force istance curve making use of the DMT model. This deviation could probably be corrected by utilizing a cantilever having a greater spring constant (Kc 100 N/m) on such a tough sample.Figure 3. Semicontact AFM image of an indent on HOPG surface (a); exact same image as within the upper panel after cropping and analysis with the software program Gwyddion (b).We now shift our consideration to flameformed carbon nanoparticle samples. Sample #1 films had been made in flame circumstances characterized by a bimodal particle size distri bution using a 1st particle mode of 2 nm plus a second mode of 125 nm [51]. Sample #2 films were produced in flame conditions in which 10 nm soot particles and aggregates are primarily made and characterized by a higher graphitization degree compared to Sample #1 particles [6,18]. The two samples for indentation measurements were collected by thermophoretic sampling inserting the substrate within the flame 100 instances (Sample #1) and 25 times (Sample #2), having a fixed residence time of one hundred mins. The thermophoretic sam pling procedure was already used to synthesize nanostructured films of carbon nanopar ticles in equivalent flame reactors [6,52]. The thicknesses with the two sampl.
