Rearranged Copolyurea Networks for Selective Carbon Dioxide Adsorption at Room Temperature

Abstract

Copolyurea networks (co-UNs) were synthesized via crosslinking polymerization of a mixture of tetrakis(4-aminophenyl)methane (TAPM) and melamine with hexamethylene diisocyanate (HDI) using the organic sol-gel polymerization method. The subsequent thermal treatment of between 200 and 400 °C induced the sintering of the powdery polyurea networks to form porous frameworks via urea bond rearrangement and the removal of volatile hexamethylene moieties. Incorporating melamine into the networks resulted in a higher nitrogen content and micropore ratio, whereas the overall porosity decreased with the melamine composition. The rearranged network composed of the tetraamine/melamine units in an 80:20 ratio showed the highest carbon dioxide adsorption quantity at room temperature. The results show that optimizing the chemical structure and porosity of polyurea-based networks can lead to carbon dioxide adsorbents working at elevated temperatures.

Template-Free Preparation of a Mesopore-Rich Hierarchically Porous Carbon Monolith from a Thermally Rearrangeable Polyurea Network

“…The polyurea network (UN) [22,23], prepared from cross-linking polymerization of an aromatic tetra-amine and an aliphatic diamine, has been reported to show thermal rearrangement chemistry, comprising the dissociation of the urea bonds to amines and isocyanates, and the trimerization of isocyanates into cyclic isocyanurate rings [24][25][26]. During the process, micro-and mesopores are generated via the expulsion of aliphatic moieties.…”