POLYMERIZATION OF D,L-LACTIDE AND GLYCOLIDE IN SUPERCRITICAL CARBON DIOXIDE
Integration of life sciences & engineering
Integration of Life Sciences & Engineering - Poster (T5-P)
Keywords: Poly(D,L-lactide-co-glycolide), biodegradable polymers, supercritical carbon dioxide, zinc (II) 2-ethylhexanoate, ring-opening polymerization
In recent years, the use of polyglycolide (PGA), polylactide (PLA) and their co-polymers as controlled drug delivery materials for medical applications is being object of increasing interest. The wide possibilities of changes in factors such as chemical structure, MWD, co-monomers ratio, cristallinity and morphology allow control the biodegradation rate of these polymers for the controlled release of medicines
One of the main factors that has to be taken in to account in the preparation of any kind of biomaterial is the possible toxicity of the compounds used for its formulation: polymer, solvent, initiator, catalyst, etc. The use of the supercritical carbon dioxide (scCO2) as green solvent fulfils all the purity and toxicity requirements to be used as solvent for such process. With this purpose the ring-opening co-polymerization (ROP) of D,L-lactide and glycolide with zinc (II) 2-ethylhexanoate (ZnOct2) as catalyst was studied in scCO2. Additionally the use of ZnOct2 instead of the conventional stannous based catalyst has the advantage of its low citotoxicity and has not been previously described for this co-polymerization in scCO2.
The kinetic behaviour of the system and the main properties of the polymer, MWD, polydispersity and physical properties of the polymer obtained are quite similar to those obtained using tin (II) 2-ethylhexanoate.
Depending on the conditions in which the polymerization is carried out particles of polymer can be obtained. The influence of the relation of monomers to scCO2, the amount of catalyst, the stirring rate and the depressurization process on the composition of co-polymer and molecular weight distribution are studied. The stirring rate and the depressurization process play an important role in the formation of particles in this kind of polymerization. At high stirring rate particles are obtained while at moderate stirring rate a bulky polymer is formed. Thermodynamic and kinetic behaviour of this copolymerization in bulk has been also studied to be used in the mathematical modelling of the supercritical process.
Presented Wednesday 19, 13:30 to 15:00, in session Integration of Life Sciences & Engineering - Poster (T5-P).
