Utilization of CO2-captured poly(allylamine) as a polymer surfactant for nanoarchitecture production in a closed CO2 cycle

Abstract

Intensified global warming, due to increased atmospheric CO₂, is an urgent worldwide issue. To reduce atmospheric CO₂ concentrations, various absorbents have been developed for its effective capture and storage. However, the CO₂ stores could become another form of waste unless they are utilized as valuable materials. This study focuses on the utilization of a CO₂-captured absorbent as a surfactant to produce nanoarchitectures in a closed loop of the CO₂ cycle. Poly(allylamine) (PAA) effectively captured carbonic acid (CA) in an aqueous medium upon the introduction of gaseous CO₂, loading the ammonium bicarbonate onto the side chains. The molecular weight of PAA showed no significant difference in its ability and efficiency to capture CA. The CA-captured PAA released the CA at room temperature upon introducing N₂ due to the transformation of the bicarbonate into carbamate – a process that was reversible and repeatable with alternating introductions of CO₂ and N₂. The CA-captured PAA was converted into a polymer surfactant through the partial ion exchange of the bicarbonate with sodium dodecyl sulfate (SDS). At concentrations below the SDS critical micelle concentration (CMC), the surfactant self-assembled into monodisperse nanospheres, which transformed into worm-like morphologies upon increasing the polymer concentration. The utilization of the CO₂ store, in this study employing ion exchange, involves releasing bicarbonate, which is recyclable as a CO₂ source. This CO₂ capture-storage-utilization in a closed loop shows promise in diminishing CO₂ emissions.