A new generation of porous polymer networks, PPNs, has been obtained in quantitative yield by reacting in superacidic media two rigid trifunctional aromatic monomers (1,3,5-triphenylbenzene and triptycene) with two ketones having electron-withdrawing groups (trifluoroacetophenone and isatin). The resulting amorphous networks are microporous materials, with moderate BET surface areas (from 580 to 790 m2 g-1) and have high thermal stability. In particular, isatin yields networks with a very high narrow microporosity contribution, 82% for triptycene and 64% for 1,3,5-triphenylbenzene. The existence of favorable interactions between lactams and CO2 molecules has been stated. The materials show excellent CO2 uptakes (up to 207 mg g-1 at 0 ºC/1 bar) and can be regenerated by vacuum, without heating. Under post-combustion conditions, their CO2/N2 selectivities are comparable to those of other organic porous networks. Because of the easily scalable synthetic method and their favorable characteristics, these materials are very promising as industrial adsorbents.