Homopolymerization L-lactide and D,L-lactide in presence of novel zinc prolinate derivatives
Recently, poly (lactide) (PLA) and poly (iÂ¥-caprolactone) (PCL) and their copolymer have attracted more attention in the fields of surgery, sustained drug delivery and tissue engineering[5-7]. These polymers have shown their potential applications in a variety of fields because of their biodegradability, biocompatibility and permeable properties. Poly (iÂ¥-caprolactone) shows lowmelting temperature (Tm~60iÂ°C) and high decomposition temperature (Td = 350iÂ°C) and degrades very slowly due to its high hydrophobicity and crystallinity. It is known that block copolymerization allows combination of the chemical properties of the main components and physical properties of the resulted copolymers can be tailor made by adjusting the molecular weights and the composition of the constituting blocks. Though several strategies have been used for preparation of PLA and PCL, the particular convenient method to synthesize these polymers is the ring opening polymerization (ROP) of lactide/ lactones and their functionally related compounds. The ring opening polymerization of lactide and iÂ¥-caprolactone give polymers with wider spectrum of properties than the polymers synthesized by copolymerization of the corresponding hydroxyacids. Such ring opened copolymers yield tough polymers with properties from rigid thermoplastics to elastomeric rubbers. The resulting hompolymres were characterized by 13C NMR, Size exclusion chromatatography (SEC), Infrared spectroscopy (IR), Differential scanning calorimetry (DSC) andMALDI ToF-MS.