Fig. 2: Preparation of the TpPa-COF-X% membrane.

a Synthetic scheme of TpPa-COF-X% membrane. b Photographs showing the transformation of the COF membrane precursor solution during the heating process. c Intensity-weighted particle size distributions of COF precursor sol-gel solutions with the addition of PPG-NH2 subjected to 0-4 hours of heating, and d where the particle size in COF precursor solutions without the addition of PPG-NH2 rapidly grew to the micrometer scale and exceeded the DLS measurement range after 1 hour of heating. e In-situ real-time monitoring of membrane fabrication and surface changes.