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Physical properties of PLGA films during polymer degradation

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Abstract

The rates of change of polymer properties (glass transition temperature, weight fraction sorbed water, and polymer molecular weight) were determined in poly (DL-lactide-co-glycolide) films under accelerated storage conditions. Films were stored at 70°C and 95%, 75%, 60%, 45%, or 28% relative humidity. Weight fraction sorbed water was determined by thermogravimetric analysis, the glass transition temperature (Tgmix) of the polymer/water mixture by modulated temperature differential scanning calorimetry, and PLGA number-average molecular weight (Mn) by size exclusion chromatography (SEC). Rates of moisture increase and Tgmix decrease were related to the decrease in PLGA Mn through a modification of the Gordon-Taylor equation. Understanding the relative rates of polymer physical and chemical degradation will allow for improved design of PLGA formulations that control rates of drug delivery and preserve drug stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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