  Phase separation has recently emerged as an important organizational
principle in the dense and heterogeneous environment within living cells. Here,
we use a synthetic system to show that compressive stresses in a polymer
network suppress phase separation of the solvent that swells it. These stresses
create a barrier to droplet nucleation that leads to robust, stabilized
mixtures well beyond the liquid-liquid phase separation boundary. Network
stresses not only alter the stability of mixtures, but they also have a
dramatic effect on the ripening of droplets. Gradients in network stresses can
drive a new form of ripening, where solute is transported down stiffness
gradients. This elastic ripening can be much faster than conventional surface
tension driven Ostwald ripening.
