Design of ZIF-8/ion copolymer hierarchically porous material: Coordination effect on the adsorption and diffusion for carbon dioxide

Abstract

The novel CO2 adsorbent (ZPMAC) was constructed by a facile in-situ growth of ZIF-8 onto the surface of a mesoporous amino-functionalized ion copolymer (PMAC). The existence of coordination effect between Zn2+ from ZIF-8 and nitrogen atom from the amino-alkyl chain in PMAC changed the pore structure of substrate for enhancing the amount of CO2 capture and accelerated the rate of CO2 adsorption. The ion copolymer PMAC, pristine ZIF-8 and hierarchically porous hybrid material ZPMAC were characterized by SEM, TEM, TGA, N2 adsorption-desorption, FT-IR, XRD, UV, and XPS techniques. It was observed that ZIF-8 loaded on the surface of PMAC uniformly and tightly. In the growth process of ZIF-8 nanoparticles, zinc ions were firstly coordinated with nitrogen atoms of the amino-alkyl chain in PMAC sample, and subsequently reacted with 2-methylimizadole to generate ZIF-8 nanoparticles. Obviously, the surface areas of ZPMAC increased and smaller peak value of micropore distribution was generated by the strong coordination interaction between ZIF-8 and PMAC after ZIF-8 modified. Meanwhile, the appearance of hierarchically porous structure was conducive to the transportation and adsorption of CO2 molecules, thus enhancing the amount of CO2 capture and the rate of adsorption effectively. This study was intended to design a new kind of hybrid materials by the means of in-situ growth of MOF materials onto the IL-type polymers and further study the influences of the structure and properties of ionic-type hybrid materials on the absorption capacity to meet the requirements of various applications.