Polycaprolactone (PCL) is a biodegradable synthetic polymer that is currently widely used in many pharmaceutical and medical applications. In this paper we describe the coordination ring-opening polymerization of ε-caprolactone in the presence of two newly synthesized catalytic systems: diethylzinc/gallic acid and diethylzinc/propyl gallate. The chemical structures of the obtained PCLs were characterized by 1H- or 13C-NMR, FTIR spectroscopy and MALDI TOF mass spectrometry. The average molecular weight of the resulting polyesters was analysed by gel permeation chromatography and a viscosity method. The effects of temperature, reaction time and type of catalytic system on the polymerization process were examined. Linear PCLs with defined average molecular weight were successfully obtained. Importantly, in some cases the presence of macrocyclic products was not observed during the polymerization process. This study provides an effective method for the synthesis of biodegradable polyesters for medical and pharmaceutical applications due to the fact that gallic acid/propyl gallate are commonly used in the pharmaceutical industry.

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Polylactide (PLA) represents one of the most promising biomedical polymers due to its biodegradability, bioresorbability and good biocompatibility. This work highlights the synthesis and characterization of PLAs using novel diethylzinc/gallic acid (ZnEt 2 /GAc) and diethylzinc/propyl gallate (ZnEt 2 /PGAc) catalytic systems that are safe for human body. The results of the ring-opening polymerization (ROP) of rac-lactide (rac-LA) in the presence of zinc-based catalytic systems have shown that, depending on the reaction conditions, "predominantly isotactic", disyndiotactic or atactic PLA can be obtained. Therefore, the controlled and stereoselective ROP of rac-LA is discussed in detail in this paper.

The results show that the obtained PURs are very effective and perspective carriers and might be potentially applied in the technology of high controlled EPI delivery systems.

Oznaczanie pozosta³ooeci cyny w syntetyzowanych biomedycznych poliestrach alifatycznych metod¹ elektrotermicznej absorpcyjnej spektrometrii atomowej Streszczenie-Metod¹ polimeryzacji z otwarciem pieroecienia, katalizowanej 2-etyloheksanianem cyny (SnOct 2) otrzymano cykliczne poliestry: polilaktyd (PLA) i poli(e-kaprolakton) (PCL). Uzyskane produkty poddawano procesowi kilkakrotnego oczyszczania z pozosta³ooeci cynoorganicznego katalizatora. Zawartooeae Sn w polimerach, po ka¿dym kolejnym oczyszczaniu, oznaczano za pomoc¹ elektrotermicznej absorpcyjnej spektrometrii atomowej (ET-AAS). Wyniki analiz dyskutowano uwzglêdniaj¹c wymagania Farmakopei Europejskiej dotycz¹ce dopuszczalnej zawartooeci cyny w biomedycznych poliestrach alifatycznych. Stwierdzono, ¿e czterokrotne oczyszczanie produktu polireakcji pozwala na obni¿enie poziomu stê¿enia Sn o 3 rzêdy wielkooeci, do wartooeci mniejszych ni¿ okreoelone przez Farmakopeê dla materia³ów maj¹cych kontakt z krwi¹, ponadto operacje te nie powoduj¹ degradacji polimeru. S³owa kluczowe: poliestry alifatyczne, polilaktyd, poli(e-kaprolakton), polimery biomedyczne, elektrotermiczna absorpcyjna spektrometria atomowa. DETERMINATION OF RESIDUAL TIN IN SYNTHESIZED ALIPHATIC BIOMEDICAL POLY-ESTERS BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROSCOPY Summary-The synthesis of the aliphatic polyesters-polylactide (PLA) and poly (e-caprolactanes) (PCL) in the ring-opening polymerization of cyclic esters in the presence tin(II) 2-ethylhexanoate (SnOct 2) has been presented. The obtained products were subjected to multiple purification procedures to remove residual organo-tin catalyst (Tables 2 and 3). The tin content in the polyesters was then determined by Electrothermal Atomic Absorption Spectroscopy (ET-AAS) (Tables 3 and 4) after each purification process. The results of the analysis were discussed taking into consideration the requirements placed by the European Pharmacopoeia regarding the amount of tin allowed in aliphatic biomedical polyesters. It was confirmed, that a four-stage purification of the polyreaction product led to a threefold decrease in the concentration of tin to a level less than the value required by Pharmacopoeia for materials designated for contact with blood. Moreover, the purification process did not generate any degradation of the polymer.