Khemchart Yuwananonta,^a Rungthip Kunthom,^b,c,* Pawares Pornchaiprasartkul,^a Siraprapa Somsri,^a Thanthapatra Bunchuay,^a Yuwanda Injongkol,^b,c Khamphee Phomphrai,^d Sareeya Bureekaew,^e Bunyarat Rungtaweevoranit,^f Preeyanuch Sangtrirutnugul^a,*

^aCenter of Excellence for Innovation in Chemistry (PERCH−CIC), Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand

^bFuturistic Science Research Center, School of Science, Walailak University, Nakhon Si Thammarat 80160, Thailand

^cFunctional Materials and Nanotechnology Center of Excellence, Walailak University, Thasala, Nakhon Si Thammarat 80160, Thailand

^dSchool of Molecular Science and Engineering (MSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong 21210, Thailand

^eSchool of Energy Science and Engineering (ESE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong 21210, Thailand

^fNational Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, 12120, Thailand.

Corresponding Author Emails: preeyanuch.san@mahidol.edu (P. Sangtrirutnugul) and rungthip.kunthom@gmail.com (R. Kunthom)

This study developed a new metal-free, reusable catalyst that converts carbon dioxide (CO₂) into valuable cyclic carbonates, which are important chemicals used in solvents, batteries, and polymer production. Two crosslinked polymers based on polyhedral oligomeric silsesquioxane (POSS), which are an ionic material (POSS-QAS-1) containing quaternary ammonium iodide groups and a neutral analogue with tertiary amine (POSS-triprop), were successfully synthesized.

In comparison, POSS-QAS-1 showed outstanding catalytic performance for the reaction between CO₂ and epoxides without requiring solvents, metal additives, or cocatalysts. Under efficient conditions (100 °C, 10 atm CO₂), the ionic polymer catalyst afforded 91% conversion of epichlorohydrin with >99% selectivity to the cyclic carbonate product (TOF = 39 h^-1). The catalyst could be reused for at least four cycles with minimal loss of activity.

Experimental and computational studies revealed that the catalyst works through a cooperative mechanism: silanol groups on the POSS framework activate the epoxide, while iodide ions promote ring opening and subsequent CO₂ incorporation. This work demonstrates that ionic POSS-based polymers are promising sustainable catalysts for CO₂ utilization, combining high activity, recyclability, and the elimination of metal-based components.