Interes ngly, in this par cular sample, mechanical strain on the phase-separated matrix is also evident. The polymer rich layer behind the drug-rich surface layer con nues to expand up un l 20 min, at which point it bursts through the drug layer, releasing most of the polymer and accompanied by a contrac on of the matrix. Regardless of this mechanical disrup on, overall, a significant amount of polymer was present in the buffer medium from 1 min onwards, while the drug signal was not detectable. Furthermore, in contrast to the 20% drug loading, neither SRS nor confocal reflec on measurements suggested the presence of any (nano)droplet forma on in the buffer-rich phase. These findings are broadly consistent with the earlier observa ons for ASDs of the same composi on .