TY - JOUR AV - none IS - 7 N2 - Usually, nitrogen and argon adsorptionâ??desorption isotherms are used at their respective boiling points for the determination of specific surface area via the BET theory of microporous materials. However, for ultra-micropores, where nitrogen and argon cannot access at cryogenic temperatures, the CO2 adsorptionâ??desorption isotherms have been considered as alternative options for the determination of specific surface area by extending BET theory, but the surface area determined by using CO2 adsorptionâ??desorption isotherms is not significant due to strong CO2-CO2 interactions. In this study, the microporous covalent organic polymers are subjected to nitrogen and CO2 adsorptionâ??desorption isotherms and the results showed that a clear linear region is available in isotherms, which confirms the presence of ultra-micropores. The surface area determined by the CO2 adsorptionâ??desorption isotherms is higher than the surface area determined by N2 adsorptionâ??desorption isotherms. These results indicate that the microporous covalent organic polymers contain ultra-micropores where only CO2 can reach, while nitrogen and argon cannot access at cryogenic conditions because their kinetic diameter is larger than CO2. © 2020, Springer Nature Switzerland AG. N1 - cited By 32 TI - Extension of BET theory to CO2 adsorption isotherms for ultra-microporosity of covalent organic polymers ID - scholars12925 KW - Adsorption; Adsorption isotherms; Argon; Carbon dioxide; Cryogenics; Desorption; Microporosity; Microporous materials; Nitrogen; Specific surface area KW - Argon adsorption; CO2 adsorption; Cryogenic conditions; Cryogenic temperatures; Desorption isotherms; Linear region; N2 adsorption; Surface area KW - Organic polymers Y1 - 2020/// PB - Springer Nature SN - 25233971 A1 - Mukhtar, A. A1 - Mellon, N. A1 - Saqib, S. A1 - Lee, S.-P. A1 - Bustam, M.A. JF - SN Applied Sciences UR - https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096140500&doi=10.1007%2fs42452-020-2968-9&partnerID=40&md5=f808294fa5ef668716429abfa6b9a5cc VL - 2 ER -