Property-Tunable 1,2-Epoxybutane-Modified Poly(Ethylene Imine) (nEB-PEI): Volumetric and Viscometric Properties of CO2-Free and Loaded Aqueous Solution at Different Temperatures

In this work, n EB-PEI 1800 ( n  = 0.22, 0.29, 0.35), a property tunable polymer for CO 2 capture, is reported by partially modifying poly (ethylene imine) (PEI 1800 ) with 1,2-epoxybutane (EB). The density and viscosity of CO 2 -free and loaded aqueous n EB-PEI 1800 solution are measured at the temperatures of (293.15 to 333.15) K and 0.1 MPa. The aqueous solutions with various weight fractions of w  = (5, 10, 15, 20 and 30%) are investigated. According to the experimental data, thermal expansion coefficient ( α p ), viscosity activation energy ( E η ) and CO 2 diffusion coefficient ( D CO2 ), are calculated. The influence of temperature, n EB-PEI concentration, CO 2 loading and modification degree are discussed from the viewpoints of molecular interaction and steric effect. The results reveal that low temperature, high n EB-PEI concentration and high CO 2 loading lead to high density and viscosity. Modification degrees have a great impact on the physical properties of n EB-PEI 1800  + H 2 O systems and can reduce the density and viscosity. The density and viscosity values exhibit the decreasing sequence of ρ PEI + H2O  >  ρ 0.29EB-PEI + H2O  >  ρ 0.35EB-PEI + H2O ≈ ρ 0.22EB-PEI + H2O and η PEI + H2O  >  η 0.22EB-PEI + H2O  >  η 0.35EB-PEI + H2O  >  η 0.29EB-PEI + H2O , respectively. All the results are attributed to the combined effects of hydrogen bonding, dispersion force and steric structure.