Within the dissolu on medium, the buffer signal is strongly visible and highly consistent (with the same shade of cyan) at all me points in the upper right-hand region of the false-color SRS images, sugges ng the medium remains predominantly unchanged over me. Indeed, the buffer coefficient values in this region (posi ve values on the x-axis to the right of the matrix-dissolu on medium interface) remained close to unity (represen ng 100%) at all mes, while the polymer and drug coefficient values remained close to zero. Overall, this suggested negligible release of both the drug and the polymer at this drug loading, and can be a ributed to the strong con nuous drug-rich network within, and especially at the surface, of the film. This network remains intact, despite some buffer penetra on into the film and film swelling.