Final Activity Report Summary - DIBOP (Novel synthesis of biodegradable aliphatic polyesters for packaging and biomedical applications) During this project we developed a new method for the synthesis of biodegradable aliphatic polyesters and copolymers using a non toxic catalyst. Poly(lactide)-block-poly(ethylene glycol), PLA-b-PEG and poly(e-caprolactone)-block-poly(ethylene glycol), PCL-b-PEG, of different structures were prepared by the ring opening polymerisation of lactides and e-caprolactone in the presence of poly(ethylene glycol) as microinitiator and a potassium compound as catalyst in toluene at room temperature. A wide range of copolymers with different compositions were prepared. The standard procedure was used to prepare poly(lactide)-b-poly(e-caprolactone) linear and star copolymers by substituting hydroxy terminated poly(e-caprolactone) for poly(ethylene glycol). The new catalyst system was investigated for the synthesis of poly(lactides), PLA; Poly(e-caprolactone), PCL and poly(trimethylene carbonate) P(TMC) homopolymers as well as PLA-b-PCL, PLA-b-PTMC and PCL-b-PTMC copolymers. Scale-up experiments were carried out at Robinson brothers Ltd and the results obtained showed no significant problems associated with the production of these materials on an industrial scale. The materials obtained were fully characterised by GPC, NMR and DSC and their physico-chemical properties were determined. The physical properties of these materials could be tailored by the proper choice of the polymer architecture and polymer composition. In vitro cytotoxicity tests on these materials were carried out in the laboratory of histology at the University of Ghent and the results obtained showed that the materials were not toxic toward the fibroblast cells. Depending on the physical properties, these materials were designed for biomedical and packaging applications. For biomedical applications, selected copolymers of poly(LL-lactide)-b-poly(ethylene glycol) were processed to form microspheres. Copolymers of low molecular weights were investigated as plasticisers for biodegradable PLA. The results showed a drastic change of the physical properties of PLA. The glass transition was decreased from 60 to 20 degrees Celsius and the elongation at break increased from 5 to 320 % without significant loss of tensile strength.
