23 Dec PGA, PLA and PLGA – Functional and biodegradable polymers
Biodegradable polymers are of great current interest for many applications. Such degradable polymers are important for the future of sustainable polymers and plastics, e.g. to resolve materials’ end-of-life and find recyclability routes. In that sense, SPECIFIC POLYMERS dedicates a significant part of its internal research to biodegradable polymers such as PGA, PLA and PLGA in the biomedical field (e.g. for drug and gene delivery systems, bioengineering scaffolds or as bioadhesives). In this research unit, special interest is given to functional polylactid acid (PLA), polyglycolic acid (PGA) and polylactic acid-co-glycolic acid (PLGA).
PGA & PLA
Poly(glycolic acid) PGA is a biodegradable thermoplastic polyester characterized by aliphatic ester bond that are responsible of its hydrolytic instability. Tg of PGA homopolymer ranges from 35°C and 40°C. Moreover, the high crystallinity of PGA (45-55%) lead to remarkable mechanical properties (elongation coefficient: 15-35%, elastic modulus: 12.5 GPa). Carbonyl groups of PGA can be cleaved under hydrolytic or enzymatic conditions. Finally, PGA is fully biodegraded by the organism within 4 months but its mechanical properties almost disappeared after 6 weeks.
Poly(lactic acid) PLA is a thermoplastic, high-strength, high-modulus polymer. Glass Transition Temperature of PLA homopolymer range from 50°C and 80°C. It has lower crystallinity than PGA (35-40%). In addition, biomedical use of PLA can be limited by its hydrophobicity which is responsible of low water sorption and thus relatively slow hydrolytic degradation. PLA mechanical properties remain quite high during the first months in physiologic conditions. In comparison with PGA, 10 months are needed to reach a full biodegradation in the case of PLA.
Poly(lactic acid-co-glycolic acid) PLGA is a biodegradable polyester which presents great interest in the biomedical field. It is possible to tune the degradation parameters and the mechanical properties of these biodegradable polyester by associating both lactic and glycolic units within the same copolymer. The degradation kinetic highly depend on LA/GA ratio. PLGA copolymers will degrade much faster than corresponding homopolymers. Furthermore, mechanical properties of PLGA copolymers can be enhanced by increasing GA content. Finally, a compromise between degradation kinetic and mechanical properties must be reached for each specific application.
Biodegradable Block Copolymers
SPECIFIC POLYMERS can synthezise various statistical and block copolymers that combine PLA, PGA or PLGA with other co-monomer (caprolactone, trimethylene carbonate, etc.) or Poly(ethylene glycol) (PEG) chains. Copolymers including biocompatible PEG chains and biodegradable PLA chains are of great interest in drug delivery.
Functional PGA, PLA and PLGA
We also perfom the synthesis of functional PGA, PLA and PLGA. Molecular weight, composition (LA/GA ratio) and functionality can be tuned depending on customer specifications. Biocompatible polyester are of great interest in various biomedical fields such as tissue Engineering, Sutures, Drug delivery, Orthopedic devices, etc.