The previous sections illustrate how a sorbent's degradation rate and form affect the overall carbon footprint and cost of DAC, with guidelines provided for economic viability. However, experimentally improving a sorbent's stability to lower the DAC cost is often not straightforward due to the interconnected nature of sorbent properties. This complexity has been observed in both crosslinking and epoxide functionalization of polyamines, where increasing the functionalization increases stability, but it also reduces the CO2 capacity and heat of adsorption. To explore this further, we built a small library of modified polyamine sorbents to study with our newly developed capacity fade model. We used a simple modification scheme to functionalize the polyamines in a mesoporous silica support (Fig. ). We hypothesized that we could use this one-step modification to tune the sorbent's heat of adsorption, working capacity, and stability through the choice of functional group and extent of functionalization. As the functional groups attach to the amine sites, the reacted primary amines will convert to secondary amines, and the secondary amines will convert to tertiary amines, which are typically inactive for CO2 capture. Increasing the proportion of secondary and tertiary amines in the sample is expected to simultaneously reduce the capacity and heat of adsorption by decreasing the binding strength of CO2 with the material. Three functional groups were tested (reagent in parentheses):