Nesibe A. Dogan1, Vepa Rozyyev1, Perman Jorayev1, Doyun Kim1, Yeongran Hong1, Saravanan Subramanian1, Damien Thirion1, Cafer T. Yavuz1,2,3,4
1Graduate School of EEWS, 2Department of Chemistry, 3Department of Chemical and Biomolecular Engineering, 4Saudi Aramco-KAIST CO2 Management Center, KAIST, Daejeon, 34141 Republic of Korea
Porous polymers with robust C-C bonded frameworks offer stability, reproducibility and tunability in carbon dioxide capture and conversions. We prepared hollow and porous microspheres of polyacrylonitrile crosslinked divinylbenzene and chemically modified into primary amines to achieve high CO2 capture capacity. The reduction was only successful with non-metal hydride sources. Microspheres were easy to handle and showed great cycle life. In order to have higher porosity, we investigated Friedel-Crafts alkylation reactions to form hypercrosslinked porous polymers. By installing chloromethyl terminals, we anchored amines on the pore walls. By varying the chain length and the nitrogen content, we discovered a wrapping mechanism that was not previously observed. We were also able to optimize binding energy around 40 kJ/mol, for high capacity with easy recyclability. For CO2 conversion into cyclic carbonates, we converted amines into quaternary ammonium structures. Under atmospheric pressure, CO2 was quantitatively added into epoxides (even challenging ones like styrene oxide) to form cyclic carbonates. We believe these methods benefitted greatly from the C-C bonded nature of the structures and similar structures will be explored for other applications such as water treatment and methane storage.