Tuning the Adsorption Capacities of Nanoporous Polyaminal Networks through Substituent Groups

Abstract

Investigating the relationship between the substituent groups of nanoporous organic polymers and the adsorption capacities of the polymers for SO 2 , NH 3 , CO 2 , and I 2 is a significant challenge. In this study, four nanoporous polyaminal networks (NPANs) with methyl or phenyl substituent groups were prepared, and they demonstrated high adsorption capacities for SO 2 , NH 3 , CO 2 , and I 2 . The four NPANs, which were referred to as NPAN-1, NPAN-2, NPAN-3, and NPAN-4, were fabricated via a one-pot polycondensation method by using inexpensive p-phthalaldehyde (p-PDA) or m-phthalaldehyde (m-PDA) and 6methyl-1,3,5-triazine-2,4-diamine (MTDA) or 2,4-diamino-6-phenyl-1,3,5-triazine (DAPT). The NPANs had a dense aminal-rich structure and stable nanoporosity, which contributed to their high adsorption capacities for SO 2 , NH 3 , CO 2 , and I 2 and their high SO 2 /CO 2 selectivities. Notably, the SO 2 adsorption capacities, NH 3 adsorption capacities, CO 2 adsorption capacities, and I 2 adsorption capacities of NPAN-1 and NPAN-3, which were NPANs with electron-donating methyl groups, were higher than those of NPAN-2 and NPAN-4, which were NPANs with electron-withdrawing phenyl groups. This result indicated that the introduction of electron-donating groups into an NPAN enhanced the electron density of the nitrogen atoms in the polyaminal network, leading to increases in the adsorption capacities of the NPAN for SO 2 , NH 3 , CO 2 , and I 2 . This study offers important insights into the design and synthesis of NPANs with adjustable properties to tackle environmental and industrial challenges.

Highly Selective SO2 Capture by Triazine-Functionalized Triphenylamine-Based Nanoporous Organic Polymers

“…ANOP-6 demonstrates higher selectivity for SO 2 over CO 2 and N 2 compared to ANOP-7, attributed to the greater proportion of microporous structure (V micro / V total ) and stronger interaction between the polymer skeletons and SO 2 . Notably, ANOP-6 and ANOP-7 exhibit impressive SO 2 /CO 2 selectivity values of 248 and 99, respectively, at 100 kPa and 298 K, surpassing the previous studies on nitrogen-containing NOPs such as sPANs (37.6–50.3), POPs (17.8–31.0), XJCOF-1 (222), HNIP-TBMB-1 (91), NPANs (51.4, 87.7), ANOP-5 (114), TAM-POF (83), and comparable to other porous materials, such as CPL-1(8.7), BC-X-650 (21–32), GU-1(15.9, 296.2 K) . Fe-MIL-127(32), ELM-12(30), ECUT-Th-60 (27), and DUTs (33–37) .…”