Design and Construction of an Azo-Functionalized POP for Reversibly Stimuli-Responsive CO Adsorption.

A porous azo-functionalized organic polymer (JJU-2) was designed and prepared via oxidative coupling polymerization promoted by FeCl. JJU-2 exhibited reversibly stimuli-responsive CO adsorption properties as a result of the trans/cis isomerization of the polymer's azo-functionalized skeleton. Under UV irradiation and heat treatment, this porous material displayed various porous structures and CO adsorption properties. The initial Brunauer-Emmett-Teller (BET) surface area of JJU-1 is 888 m g. After UV irradiation, the BET surface area decreases to 864 m g, along with the decrease of micropores around 0.50 nm and 1.27 nm during the trans-to-cis isomerization process. In addition, CO sorption isotherms demonstrate an 8%t decrease, and the calculated Qst of CO has decreased from 29.0 kJ mol to 26.5 kJ mol due to the trans to cis conversion of the azobenzene side group. It is noteworthy that JJU-2's CO uptakes are nearly constant over three cycles of alternating external stimuli. Therefore, this azo-functionalized porous material was a potential carbon capture material that was responsive to stimuli.