Extended Data Fig. 1: Density measurements.

Solution density (black circles) as a function of concentration and temperature for colloidal solutions of 90-nm silicalite-1 nanocrystals in water (a–c), a colloidal solution of 90-nm silicalite-1 nanocrystals with 5 wt% dextrose in water (d–f), colloidal solutions of 90-nm silicalite-1 nanocrystals in ethanol (g–i), colloidal solutions of zeolite LTL nanocrystals in water (j–l), colloidal solutions of (mPEG)ZIF-8 nanocrystals in water (m–o), a colloidal solution of (mPEG)ZIF-8 with 5 wt% dextrose in water (p–r) and colloidal solutions of ZSM-5 nanocrystals (Si/Al = 64) in water (s–u). A gradient shows the possible range of theoretical densities for different degrees of pore filling, from air-filled (grey) to solvent-filled (blue or purple) micropores. Note that the maximum pore-filling density corresponds to the bulk solvent density, but the density of nanoconfined solvent is often lower than the bulk solvent density²⁴.