Fig. 4: Ostwald ripening in complex coacervates.
From: Active coacervate droplets are protocells that grow and resist Ostwald ripening
a Schematics of the distinct behaviour observed for oil-based droplets and complex coacervate droplets. b The local rates can be used to quantify that distinction: active coacervates grow (phases I and II are discussed below in Fig. 5), and passive coacervates (high or low droplet densities) remain stable in size; the shrinkage of some droplets of 1-bromododecane (BrC12) and 1-bromopropane (BrC3) can be detected in our method as negative local rate values. Although the median growth rate for BrC12 is positive, we see a significant fraction of droplets with a negative value, unlike the results for coacervates. Active and passive coacervates are significantly different (*) in a Mood’s median test (P < 0.05). Source data are provided in Supplementary Data 1. A complete overview of experimental conditions and sample size can be found in Supplementary Table 1. c Rationalization of suppressed Ostwald ripening in complex coacervates, taking into account two possible mechanisms: in (i), free poly-electrolytes, in this case, K72, are transferred, leaving an oppositely charged droplet. In (ii), coarsening happens through the transfer of electroneutral complexes from small to larger droplets. This complex has an interfacial area, represented by the green droplet encasing it. Next to each mechanism, the energy balance estimation for each of the mechanisms envisioned.
