## Results and Discussion
\begin{table}
\begin{tabular}{l l} \hline \hline
**Chemical shift in ppm** & **Structural assignments** \\ \hline _poly(\(\varepsilon\)-caprolactone)_ & \\
4.01 & (2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**OC(O)-)** \\
3.70 & (2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**OH, end group)** \\
2.24 & (2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**COO-)** \\
1.58 & (4H, m, -CH\({}_{2}\)**CH\({}_{2}\)**COO-)** \\
1.33 & (2H, m, -CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**-)** \\
173.1 & (**-C**(O)O-)** \\
63.7 & (**-CH\({}_{2}\)**CH\({}_{2}\)**OC(O)-)** \\
33.6 & (**-CH\({}_{2}\)**CH\({}_{2}\)**COO-)** \\
27.9 & (**-CH\({}_{2}\)**CH\({}_{2}\)**OC(O)-)** \\
25.1 & (**-CH\({}_{2}\)**CH\({}_{2}\)**COO-)** \\
24.1 & (**-CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**-)** \\ \hline _polyactides_ & \\
5.17 & (1H, q, -**CH**(CH\({}_{3}\))-)** \\
4.36 & (1H, q, -**CH**(CH\({}_{3}\))OH, end group) \\
1.58 & (3H, d, -**CH\({}_{3}\))** \\
169.80 & (**-C**(O)O-)** \\
69.2 & (**-CH**(CH\({}_{3}\))-)** \\
16.8 & (**-CH\({}_{3}\))** \\ \hline _\hline _\multicolumn{2}{l}{_\(\varepsilon\)-caprolactone and lactide copolymers_} \\
5.15 & 1H, q, -**CH**(CH\({}_{3}\))- \\
4.27 & 1H, q, -**CH**(CH\({}_{3}\))OH, end group \\
4.11 & 2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**OC(O)-LA** \\
4.03 & 2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**OC(O)- \\
3.67 & 2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**OH, end group \\
2.37 & 2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**COO-LA** \\
2.29 & 2H, t, -CH\({}_{2}\)**CH\({}_{2}\)**COO- \\
1.63 & 4H, m, -**CH\({}_{2}\)**CH\({}_{2}\)**COO- \\
1.59 & 3H, d, -**CH\({}_{3}\)** \\
1.34 & 2H, m, -CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**CH\({}_{2}\)**-** \\ \hline \hline \end{tabular}
\end{table} 
Table 2: \({}^{1}\)H- and \({}^{13}\)C-NMR structural assignments of the synthesized polyesters (spectrum recorded in chloroform at room temperature). Insertion of the carnitineing fragment into the polymer chain was confirmed by the proton NMR spectral analysis. The peaks at 2.83 (-**CH\({}_{2}\)**COOH), 3.51 ((CH\({}_{3}\))\({}_{3}\)N\({}^{+}\)-) and 3.43 (-**CH\({}_{2}\)N\({}^{+}\)-) ppm were observed in all products obtained by homo- and copolymerization of CL, LA and LLA in the presence the carnitineine/SnOct\({}_{2}\) system. Composition of the CL and LA (PCLLA) copolymers was deduced from the \({}^{1}\)H-NMR spectra. The CL content in the copolymer of CL and LA exceeded the CL feed ratio for PCLLA (amounts to 56-58 mol %). Probably, CL is the most active co-monomer in this reaction. The MALDI-TOF spectra of PCL contain double peaks, each component corresponding to a separate spectrum series. The most prominent series of peaks is characterized by a mass increment of 114 Da, which is equal to the mass of the repeating unit in the poly(\(\varepsilon\)-caprolactone) (Figure 3). It is assigned to PCL terminated with a hydroxyl group (residual mass: 57 Da, K\({}^{+}\) adduct) (A). The second series of peaks also corresponded to poly(\(\varepsilon\)-caprolactone), terminated with a hydroxyl group (residual mass: 40 Da, Na\({}^{+}\) adduct) (B). In the MALDI-TOF spectra of PLA there are also two series of peaks. The main series corresponds to PLA molecules, terminated with a hydroxyl group (residual mass: 41 Da, Na\({}^{+}\) adduct), and the second series of smaller peaks corresponds also to PLA terminated with a hydroxyl group (residual mass: 57 Da, K\({}^{+}\) adduct). In the MALDI-TOF spectrum of PLA both populations of chains of even and odd number of lactic acid m.u. can be observed. The odd number of acid m.u. shows that under the reaction conditions the polymer chain undergoes intermolecular transesterification (leading to an exchange of segments), which is a typical phenomenon for the polymerization of lactides [18].