Pore Engineering in Hyper-cross-linked Polymers: Directional Etching to Enhance CO2 Adsorption and Conversion

Abstract

Hyper-cross-linked polymers (HCPs) are promising for CO₂ adsorption and catalysis. However, optimizing their performance remains challenging. Here, we report a pore engineering strategy to construct hydroxyl-functionalized HCPs-X-HFA (X = 1, 2, or 3) via Friedel–Crafts alkylation followed by hydrofluoric acid (HFA) etching. This approach significantly increases specific surface area and pore volume of HCPs-X-HFA, thereby enhancing CO₂ adsorption and CO₂/N₂ separation selectivity, with up to 3.41 mmol·g^–1 at 0 °C. These polymers also serve as recyclable catalysts for CO₂ conversion into cyclic carbonates under mild conditions (60 °C, 1 bar CO₂) with tetrabutylammonium bromide as a cocatalyst, achieving a yield of 90–99%. The high catalytic activity stems from abundant hydroxyl groups formed postetching, which anchor CO₂ via hydrogen bonds and activate epoxides for ring-opening. This study offers insights into designing porous organic polymers with dual CO₂ adsorption and catalytic functions.