Synthesis of size-tuneable CO2-philic imprinted polymeric particles (MIPs) for low-pressure CO2 capture using oil-in-oil suspension polymerisation

Highly selective molecularly imprinted poly[acrylamide-co-(ethyleneglycol dimethacrylate)] polymer particles (MIPs) for CO2 capture were synthesised by suspension polymerisation via oil-in-oil emulsion. Creation of CO2-philic, amide decorated cavities in the polymer matrix led to a high affinity to CO2. The imprinted polymers showed markedly higher CO2 uptakes compared to their non-imprinted counterparts, and the maximum equilibrium CO2 capture capacity of 1.1 mmol g-1 was achieved at 273 K. At 0.15 bar CO2 partial pressure, the CO2/N2 selectivity was 49 (corresponding to 91% purity of the gas stream after regeneration), and reached 97 at ultra-low CO2 partial pressures. The heat of adsorption was below 32 kJ mol-1 and the temperature of onset of intense thermal degradation was 351-376 °C. An increase in monomer-to-crosslinker molar ratio in the dispersed phase up to 1:2.5 led to a higher affinity towards CO2 due to higher density of selective amide groups in the polymer network. MIPs are a promising option for industrial packed and fluidised bed CO2 capture systems due to large particles with a diameter up to 1200 μm and irregular oblong shapes formed due to arrested coalescence during polymerisation, occurring as a result of internal elasticity of the partially polymerised semisolid drops.