Digital and experimental design of CO2-responsive polymers based on acrylamide monomers for carbon capture

Abstract

This study provides a comprehensive evaluation of the CO₂ capture performance of the CO₂-responsive homopolymer poly(N-[3-(dimethylamino)propyl]-acrylamide) (PDMAPAm) and its diblock copolymer poly(N-[3-(dimethylamino)propyl]-acrylamide)-b-poly(methyl methacrylate) (PDMAPAm-b-PMMA), with a particular emphasis on their integration into membrane adsorbers for direct air capture (DAC) applications. A central novelty of this work is the development of a pioneering unified kinetic model that, for the first time, couples polymerization reaction kinetics with CO₂ adsorption kinetics. This model enables the digital predictive design of polymer materials whose CO₂ uptake is expressed directly as a function of polymer properties. By systematically varying the molar mass of the amine-functional PDMAPAm block and the poly(methyl methacrylate) (PMMA) content, this study identifies the optimal polymer properties that balance high CO₂ uptake with favorable processing characteristics. Adsorption experiments conducted under dry conditions revealed a physisorption-dominated mechanism, where CO₂ primarily interacts with tertiary amine and carbonyl functional groups. Notably, the unified model predicted a target molar mass of 18.5 kDa for the homopolymer of PDMAPAm and identified the optimal synthesis ratio of RAFT : initiator : monomer. This model also accurately forecasts the CO₂-uptake capacity of the PDMAPAm homopolymer to be 0.05 mmol g⁻¹ and that of its corresponding diblock copolymer (PDMAPAm-b-PMMA) to be approximately 0.1 mmol g⁻¹ under dry ambient conditions.