FRAP recovery curves of TfT or SYBR Gold residing in different microdroplets. A shows the recovery of both dyes in polyLA, while B shows the recovery of both dyes in polySA, highlighting the property that one droplet type may only afford stable compartmentalization to certain dyes. C shows the recovery of SYBR Gold in all droplet types, while D shows the recovery of TfT in all droplet types, highlighting the property that the same dye may be afforded stable compartmentalization only in certain droplet types. See SI Appendix, Table S6 for a list of all droplets probed with FRAP and their respective recovery kinetics, and Movies S10 and S11 for selected representative movies of the droplet FRAP experiments.