Sub-nm Pore Size of Phenylethynyl End-Capped Imide Oligomer-Derived Carbon for Molecular Sorption and Separation

Carbon molecular sieves (CMSs) derived from polymer precursors that can be prepared at scale are attractive for various energy-efficient sorption and separation technologies, such as hydrogen recovery, air purification, and hydrocarbon separation. Preparing CMSs with uniform sub-nm pores is prudent but rarely studied. Here, we report the use of phenylethynyl-terminated crosslinkers to control pore size, leading to highly uniform pore formation between 6 and 7 Å. We demonstrate that incorporating phenylethynyl-terminated functionalities into thermally rearrangeable (TR) imide oligomers with asymmetric chemical structures results in CMSs with consistent pore sizes (6–7 Å), high surface areas (up to 775 m 2 /g), and excellent CO 2 sorption performance (3.17 mmol CO 2 /g of CMS). Additionally, our results indicate that sub-nm pore formation can be further tailored through polymer network architecture, leading to variable surface areas (569–735 m 2 /g), which is accomplished through composition control of polymer precursors with and without TR capabilities. The fundamental understandings about the impact of the molecular design of phenylethynyl-terminated polymer precursors on their derived carbon structure can provide critical insights into their rational design for future molecular sorption and separation applications.