## 3 Results and Discussion
### X-ray Photoelectron Spectroscopy (XPS)
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Components of XPS C 1s Signal (Total C 1 s Intensity = 100)**} & \\ \cline{2-5}
**Sample** & **C-C/C-H** & **C-OH** & **COC (Comp)** & **O=C-O** & **O/C** \\  & **(Comp (1))** & **(Comp (2))** & **(3)** & **(Comp (4))** & **Ratio** \\ \hline BC & 14 & 61 & 25 & 0 & 0.69 \\
120 s Ar\_BC & 19 & 53 & 20 & 7 & 0.73 \\
240 s Ar\_BC & 26 & 49 & 17 & 7 & 0.62 \\
480 s Ar\_BC & 34 & 39 & 18 & 8 & 0.56 \\
960 s Ar\_BC & 38 & 33 & 21 & 6 & 0.64 \\ \hline \hline \end{tabular}  
* The high-resolution spectra of the XPS C 1s lines acquired for all examined samples are presented Figure 2. A deconvolution model which consists of four basic components of C 1s transition was applied. The component denoted as Comp (**1**), having a binding energy of 285.0 \(\pm\) 0.1 eV, essentially corresponds to nonfunctionalized carbon atoms. The component Comp (**2**), having a binding energy of 286.7 eV, is ascribed to a group of differently bonded  
\end{table} 
Table 2: The percentage of Comp (**1**)–Comp (**4**) components in the total signal of the XPC C 1s line and the ratio of oxygen atoms to carbon atoms on the surfaces of bacterial cellulose exposed to LPArP depending on the treatment time (s). carbon atoms linked to one atom of oxygen, as in hydroxyl group C-OH. Comp (**3**), located at a binding energy of 288.2 \(\pm\) 0.1 eV, is ascribed to O-C-O bonding. The component Comp (**4**), having a binding energy of 289.6 \(\pm\) 0.1 eV, corresponds to O-C=O bonding. The values of the binding energies used in the present model are based on the deconvolution models applied elsewhere [33]. The percentage of Comp (**1**)-Comp (**4**) components in the total signal of the XPS C 1s line is presented in Table 2.  
Highly purified bacterial cellulose should contain only carbon-oxygen bonds corresponding to Comp (**2**) and Comp (**3**) of the model used to analyze the XPS C 1s spectra. The theoretical ratio of these components should be 80:20, respectively. It is common for real cellulose samples to have Comp (**2**) accounting for about 60% of the signal from carbon atoms and Comp (**3**) about 20% of this signal. In actual samples, even of pure cellulose, a component corresponding to Comp (**1**) is also identified, which accounts for less than 20% of the C 1s signal [43]. The XPS C 1s spectrum of the reference material (BC) used in this study was very close to those reported. Exposure of this material to plasma results in several characteristic changes in the composition of its surface. As the exposure to  
Figure 2: High-resolution XPS C 1s spectra of non-modified BC and bacterial cellulose (Ar_BC) modified by different exposure times to LPArP. plasma increases, the concentration of Comp (**2**) decreases and the concentration of Comp (**1**) unequivocally increases. The decrease in Comp (**2**) is most likely due to the removal of hydroxyl groups from the cellulose surface. The removal of such bonds is accompanied by a simultaneous increase in the concentration of C-C- or C-H-type bonds, i.e., Comp (**1**). The concentration of Comp (**3**) is essentially independent of the plasma exposure. This component corresponds to the presence of an O-C-O bond at the C\({}_{1}\) carbon in the pyranose ring. This suggests the stability of the pyranose ring during the plasma action on the cellulose surface. The exposure to argon plasma also induces the appearance of Comp (**4**), which is directed to the oxidation of D-glucose alcoholic group C-OH without significant effect on the integrity of the pyranose ring. The changes in the BC surface composition demonstrated by the XPS analysis are in good agreement with the ATR-FTIR and showed that BC surfaces can be more negatively charged as a result of the presence of the carboxyl group.