Amine-based sorbents are a common choice in DAC technologies due to their high affinity for CO2, even at low concentrations. Amines bind CO2 through chemical bonds to form carbamate, carbamic acid, hydronium carbamate, carbonate, or bicarbonate; the end-product depends on the amine surface coverage, presence of water, and amine-solid support interactions. This results in steep adsorption isotherms (strong Type I) that lead to significant CO2 uptakes at low CO2 partial pressures -a critical feature for DAC applications. Implementing amines in structured contactors can enable a lower pressure drop, indirect heating, and thermal management (i.e., cooling) during adsorption. Temperature or temperature/vacuum swing adsorption are the process modes typically coupled with amine sorbents, as the high uptake at low partial pressures makes adsorption based on pressure swing alone a challenging option. Polymeric or oligomeric amines (polyamines) are a particularly promising form of amine due to their high density of amine sites and lower volatility compared to smaller amine molecules. Modification of polyamines with epoxide groups has been explored previously as a method for enhancing sorbent properties. Choi et al. demonstrated that functionalizing poly(ethyleneimine) with 1,2-epoxybutane reduces the heat of adsorption and increases the stability by altering the primary, secondary, and tertiary amine fractions. Increasing the extent of functionalization increasingly benefits the heat of adsorption and stability, but it also negatively impacts the sorbent's capacity. It remains unclear which functional group and extent of functionalization result in the most economically advantaged DAC process, but we hypothesized based on previous work from Min et al. that this functionalization could be used to systematically tune sorbent properties for optimal DAC performance. All previous optimization has been performed for post-combustion CO2 capture processes, but the optimum properties will depend on the concentration of CO2 in the feed. For example, Lively and Realff demonstrated that as the adsorbate mole fraction decreases, the adsorbate-adsorbent affinity resulting in the highest separation efficiency increases. When coupled with a capacity fade economic model, the one-step modification of polyamines could be used to target a combination of sorbent properties that results in the lowest cost of CO2 capture. This led us to the final two questions addressed in this work: (3) Can we modify polyamine sorbents with different functional groups to systematically tune performance in DAC (working capacity, heat of adsorption, degradation rate)? (4) Which combination of properties results in the most economically advantaged sorbent for DAC?