Synthesis of Biodegradable Copolymers with the Use of Low Toxic Zirconium Compounds. 1. Copolymerization of Glycolide with l-Lactide Initiated by Zr(Acac)₄

Abstract

The paper describes a new method of copolymerization of glycolide with l-lactide with the use of a low toxic compoundZr(acac)4as initiator at a temperature of 100 up to 150 °C. Copolymerization at 150 °C is very fast and reached nearly 100% yield. The values of the copolymerization coefficients were estimated as r G = 3.3 and r L = 0.5. The process of chain propagation was also examined, and a significant influence of transesterification on the final structure of copolymer was observed. The microstructure of the chain was determined by NMR spectroscopy. It was found that more segmental structure had been formed as compared with the structure of the copolymer obtained in copolymerization initiated by tin compounds. This structure influences thermomechanical properties of the copolymers. The crystallinity of copolymers obtained is higher than that of the formed in the presence of Sn(oct)2. One of their most characteristic features concerned their good mechanical properties, in many cases better than those of adequate copolymers obtained with the use of tin compounds as initiators.

Hydrolytic Degradation of Poly(L-Lactide-co-Glycolide) Studied by Positron Annihilation Lifetime Spectroscopy and Other Techniques

“…• C by a conventional method using a vacuum line for degassing and sealing of the ampoules as described previously [17]. The molar ratio of the initiator and the monomers was 1.2 × 10 −3 .…”

Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters

“…These side reactions can occasionally occur between the growing chain and preformed segments, while they cannot be generated by a coordination-insertion polymerization of the monomers. The quantification of these signals showed that the behavior of the catalysts 11 and 12 was in contrast with that of the classical Sn(Oct) 2 catalyst [56]. In particular, in the copolymerization of GA and rac-LA catalyzed by dimethyl(salicylaldiminato) aluminum compounds the transesterification due to the attack of active lactidyl chain end on already formed glycolidyl segments was favored.…”

Fabrication of Plga/Hap and Plga/Phb/Hap Fibrous Nanocomposite Materials for Osseous Tissue Regeneration

“…The study was performed using a fibre-forming copolymer of PLGA obtained by synthesis conducted in bulk, initiated by zirconium acetylacetonate (IV), according to the modified method described by Dobrzyński et al [38]. The copolymer containing 84% molar lactide units, 16% molar glycolide units and less than 1% by weight unreacted L-lactide had a number average molar mass Mn = 130 000 Da, a glass transition temperature T g = 54 °C, a melting temperature T m = 155 °C and a melting heat dH = 45 J/g.…”