Tetraethylenepentamine (TEPA) was modified by Michael addition reactions to study the effect of primary, secondary, and tertiary amine structure on its ability to absorb or desorb carbon dioxide. TEPA and modified TEPA were impregnated in a poly(methyl methacrylate) support to obtain solid amines. The specific characteristics such as pH, viscosity, and thermal stability were measured to study the properties of liquid amine. Structural properties, adsorption capacity, rate of adsorption, desorption energy, and sorbent durability during CO2 adsorption/desorption processes were measured to study the properties of solid amines. The pH of modified liquid TEPA (T1AN, T2AN, and T3AN) was slightly reduced; however, both viscosity and thermal stability were increased. The increased viscosity of the modified amines was indicative of an increase in attraction between the amine molecules; accordingly, amine leaching decreased noticeably and thermal stability of amines increased. Modified amine-impregnated sorbent (ST1AN and ST2AN) showed slight decrease in CO2 adsorption capacity but noticeable increase in rates of adsorption, durability during cyclic tests, and desorption characteristics compared to TEPA-impregnated sorbent (STEPA). (C) 2014 Elsevier B.V. All rights reserved.