## 3 Results
### Chemical Composition  
The XPS technique was used to determine the chemical composition of the CPD nanoparticles (elemental composition and characteristic bonds identified) and fullerene C\({}_{60}\) film. The data presented in Table 1 indicate that the content of C was the highest (83.1 At%), whereas the content of oxygen was the lowest (7.3 At%) for the CPD sample. Table 2 presents the characteristic bonds identified in the CPDs sample and the relative concentration of these bonds in % with respect to the total amount of the specific element (C, O, N). The content of pyrrol bonds was the highest. C=N-C bonds were also detected, and the presence of these bonds contributed to the new properties of these dots. \begin{table}
\begin{tabular}{l c c} \hline  & **CPD** & **C\({}_{60}\)** \\ \hline
**Element** & **At\%** & **At\%** \\ \hline C 1 s & 83.1 & 90.0 \\ O 1 s & 7.3 & 10.0 \\ N 1 s & 9.6 & 0.0 \\ \hline \end{tabular}
\end{table} 
Table 1: Elements identified in the CPD and C\({}_{60}\) samples in At%. Figure 3: Top view AFM images of surface morphology (left column) and corresponding EFM phase retrace mode images of surface of CPDs (**a,b**), CPDs/PU (**d,e**) and C\({}_{60}\)/PU composite films (**g,h**). Dark voids represent CPDs themselves (**b**), and CPDs in the interior of polymer matrix (**d**) and C\({}_{60}\) into the polymer matrix (**f**). (**c,f,i**) show profiles of CPDs, CPDs inside PU and C\({}_{60}\) in the interior of PU. Tip voltage was 3 V; room humidity was 35%. Table 1 lists the content of the C\({}_{60}\) film as well. From this table, we can observe that the content of C 1 s was the highest (90 At%), whereas the content of O 1 s was 10 At% for the C\({}_{60}\) film sample. Table 2 lists the binding energies of the characteristic bonds identified in the C\({}_{60}\) film and the relative concentration of these bonds in % with respect to the total amount of the specific element (C, O). It is known that O\({}_{2}\) or H\({}_{2}\)O molecules are physisorbed on C\({}_{60}\) molecules, and the presence of an O 1 s peak in the XPS spectrum of C\({}_{60}\) originates from that [40]. Figure S1a presents the FTIR spectra of C\({}_{60}\) (green curve) and the CPD nanoparticles (red curve). The following spectra were identified in the FTIR spectra of the CPD nanoparticles: the peak at 3300 cm\({}^{-1}\) could be assigned to O-H stretching vibrations in the intermolecular bonding, whereas the peaks at 2956 and 2871 cm\({}^{-1}\) originated from C-H stretching vibrations of the CH\({}_{3}\) groups. The peak at 2922 cm\({}^{-1}\) stemmed from C-H stretching vibrations of the CH\({}_{2}\) groups. At 1666 cm\({}^{-1}\), we identified C=N stretching vibrations, whereas at 1435 cm\({}^{-1}\), we detected O-H bending vibrations. The peak at 1367 cm\({}^{-1}\) stemmed from N-O symmetric stretching vibrations, whereas the peak at 1290 cm\({}^{-1}\) was assigned to a C-N stretching aromatic amine. The peak at 881 cm\({}^{-1}\) originated from C-H bending vibrations [41]. The following peaks were detected in the FTIR spectra of the C\({}_{60}\) toluene solution: the peak at 3462 cm\({}^{-1}\) stemmed from O-H stretching vibrations in the intermolecular bonding, the peaks at 2956 and 2860 cm\({}^{-1}\) were assigned to C-H stretching vibrations of the CH\({}_{3}\) groups and the peak at 2930 cm\({}^{-1}\) originated from C-H stretching vibrations of CH\({}_{2}\) groups. The peak at 1624 cm\({}^{-1}\) stemmed from C=C stretching vibrations, whereas the peak at 1454 cm\({}^{-1}\) was assigned to C-H bending vibrations. The peaks at 1256 and 1043 cm\({}^{-1}\) originated from C-O stretching vibrations. The obtained spectra agree with the recorded XPS spectra. Figure S1b shows the FTIR spectra of neat PU (black curve), CPDs/PU (red curve) and C\({}_{60}\)/PU (green curve).