The aim of the present study was to investigate the structure of free films of Eudragit® L 30D-55 containing different concentrations (0%, 1% or 5%) of diclofenac sodium by positron annihilation spectroscopy. The data revealed that the size of the free-volume holes and the lifetimes of ortho-positronium atoms decreased with increase of the API concentration. Films containing 5% of the API exhibited a different behavior during storage (17°C, 65% relative humidity (RH)) in consequence of the uptake of water from the air.
- Diclofenac sodium
- Eudragit L 30D-55
- Polymer films
- Positron annihilation spectroscopy
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