Movie S8.

Time lapse imaging of a raft pair in a chiral background, Φ_ch = 0.4, shows an unstable counter-twisted raft. The counter-twisted left-handed raft in the bound pair shrinks over a period of hours until the pair falls apart. At this point the shrunken raft begins to recover in size, indicating that it has switched its twist state to the favorable right-handed conformation. Images acquired using phase contrast microscopy. Scale bar is 2 μm.