A frontal polymerization method is used to produce highly porous polymer monoliths. The method is an approach to polymer synthesis that exploits the heat produced by the reaction itself. This heat triggers polymerization of neighboring monomer molecules, leading to a self‐sustaining hot front, which propagates along the reacting vessel. Dissolved or microencapsulated foaming agents are decomposed only at the fronts, synchronizing the polymerization and the foaming. The ultimate pore structures appear to depend on the polymerization‐front velocity and temperature. The resultant materials are porous, exhibiting tunable pore volume and a multimodal pore size distribution. No organic solvents or high‐pressure equipment are used in the process, and no solvent residues are left in the resulting materials. Specifically, this route allows for the synthesis of large‐scale samples with the additional advantages of high velocity, low energy cost, and the avoidance of multiple process steps. Substitution of hydrophilic acrylamide, N‐isopropylacrylamide, with hydrophobic styrene and methyl methacrylate also leads to porous monolithic materials, suggesting that frontal polymerization represents a powerful and facile method for an exothermic polymerization reaction and the creation of porous polymers.

Polyacrylamide hydrogels with defined porous structure were synthesized through frontal polymerization (FP) in the presence of NaHCO3 as a foaming agent. Pore properties were analyzed using scanning electron microscopy and mercury intrusion porosimetry. The as‐prepared hydrogels displayed a small cell diameter of ca 2 µm. The dissolved foaming agent dispersing at the level of molecules and the polymerization front propagating step by step should be responsible for the small uniform cell structure. The pore volume varied from 0.63 to 3.65 cm3 g−1 and the bulk density changed from 0.48 to 0.28 g cm−3 for a foaming agent content from 0 to 18%. The hydrogels synthesized by FP exhibited higher swelling rate and swelling ratio with respect to conventional batch polymerization. The highest swelling ratio and rate were obtained at a foaming agent concentration of 12% based on monomer. Copyright © 2007 Society of Chemical Industry