Serinol as a tunable and sustainable framework for high capacity, low viscosity, water-lean CO2 capture and switchable solvents

Abstract

Water-lean solvents have emerged as alternatives to conventional aqueous amines for CO₂ capture, although there is delicate balance between achieving high CO₂ loadings while maintaining sufficiently low viscosity. In this work, we present the advantages of serinol as a framework for designing single component water-lean solvents which meet these criteria. Starting from commercially available glycidyl ethers or epichlorohydrin, several symmetric and non-symmetric 1,3-diether-2-amino molecules were synthesized and thoroughly studied. Spectroscopic analyses (¹³C NMR and FTIR) confirmed chemical reactions between CO₂ and the serinol-based water-lean solvents. CO₂ absorption studies showed these solvents had high loading capacities with positive indications for stability and recyclability. The serinol-based molecules have low viscosities in their neat states (1–4 cP at 30 °C) with viscosities as low as 28 cP at 30 °C in highly CO₂-rich states. Furthermore, based on choice of functional groups, serinol-based molecules also show potential as switchable solvents that transition from hydrophobic to hydrophilic upon reaction with CO₂. Our molecular-level simulations reveal how CO₂ binding alters H-bonding networks, reduces free volume, and dramatically increases viscosity with increasing levels of complexation, mirroring the trends observed experimentally. The simulation data also support the observed switchable solvent behavior by elucidating the structural reorganization and dynamic constraints induced by CO₂ loading.