Poly(lactic-co-glycolic acid) (PLGA), is a commonly used biodegradable polymeric biomaterial used to make many biomedical products including drug delivery particles. The glass transition temperature (Tg) of a polymer particle can have a profound effect on its behavior in vivo such as mechanical properties and drug release profile. Particles loaded with drug are often plagued with a sudden burst release before the slower, more controlled release of the drug. One reason for this burst release is the relaxation of the polymer chains in the particle once at physiological temperature. By understanding and tuning the Tg of the particles, this burst release can be controlled. Bulk PLGA has a Tg of approximately 40°C, however, many factors can affect the Tg of a particle, such as molecular weight (MW), co-monomer ratio, thermal history, confinement effects, and interfacial interactions. Considerable research has characterized the role of confinement effects and interfacial effects on the resulting Tg of polymer thin films, and to a lesser extent, in particles. Much of this work, however, has focused on polystyrene and not PLGA. Furthermore, previous work does not take into account the role of thermal history as it is often difficult to separate thermal history from confinement effects. Most Tg experiments are done with polymer samples in the bulk form that have been annealed to erase thermal history. In this work, PLGA particles with different thermal history are made by nanoemulsion and nanoprecipitation and the Tg of the particles is measured using the first heating scan of a modulated differential scanning calorimetry (MDSC) run to determine the role of processing conditions on the Tg of PLGA particles. The nanoemulsion and nanoprecipitation processing conditions to create PLGA particles both increased the Tg of the PLGA compared to bulk. Furthermore, PVA, used as a surfactant during the particle production, was found to still be present in the nanoprecipitation samples, even after repeated washing, and effected the Tg of the particles.

Effect of thermal history on the glass transition temperature of poly(lactic-co-glycolic acid) particles

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.