New hyper-crosslinked polymers for enhanced CO2 adsorption: Synthesis and characterization

Abstract

In this study, new hyper-crosslinked polymers (HCPs) were synthesized with 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and p-naphtholbenzeine (NB) with different ratios of 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCMBP) through the Fridel-Crafts (FC) method. The polymers were thoroughly characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and x-ray diffraction (XRD) confirming the successful synthesis of HCP-PTCDAs and hyper crosslinked p-naphtholbenzein polymers (HCP-NBs). BET analysis revealed that the maximum surface areas of HCP-PTCDA and HCP-NB were 962 m² g⁻¹ and 665.4 m² g⁻¹, respectively. The maximum pore volumes of HCP-PTCDA and HCP-NB were 1.26 cm³ g⁻¹ and 1.90 cm³ g⁻¹, respectively. The enhanced surface area and pore volume of HCP-PTCDAs were attributed to the lack of conformational changes in PTCDA during synthesis. The maximum CO₂ adsorption capacities of the two polymers were obtained with HCP-PTCDA/20 and HCP-NB/5 (at 273 K and 1 bar: 2.75 mmol g⁻¹ and 3.28 mmol g⁻¹, respectively). Although the surface area of HCP-NB/5 was three times lower than HCP-PTCDA/20, it showed higher CO₂ adsorption performance. Accordingly, these results revealed that pore volume and size distribution were one of the most determining parameters in CO₂ adsorption. Compared with the literature, the improved CO₂ adsorption performance, especially that of HCP-NB/5, showed that these polymers had relatively high potential.