# Hydrophobic Fluorinated Porous Organic Frameworks for Enhanced Adsorption of Nerve Agents
## 3 Results and Discussion
### Dynamic Adsorption of DMMP  
The dynamic adsorption of DMMP was evaluated under air conditions with a relative humidity of 0%, 20%, and 60%, respectively. To conduct DMMP adsorption experiment under a certain humidity that is comparable to those between C-1 and C-1-F, 20% relative humidity was used whereby C-1 remained stable. In addition, the water vapor dynamic adsorption experiment was carried out at a 20% relative humidity with similar conditions as for the DMMP adsorption experiment. According to Figure 11, characteristic peaks of FT-IR spectra remain relatively unchanged after the water vapor dynamic adsorption, which verifies the stable existence of C-1 at 20% relative humidity condition. Furthermore, since C-1-F exhibits perfect stability even under high relative humidity (Figure 8b), we have also performed the dynamic adsorption of DMMP under a relative humidity of 60%, which presents a closer approximation to the real operating environment.  
The adsorption capacities of C-1 and C-1-F for DMMP and the effect of humidity on their performance were compared with the corresponding results obtained for activated carbon. Under dry air, both C-1 and C-1-F showed a dynamic adsorption performance for DMMP and the adsorption capacity of C-1-F (13.73%) was higher than that of C-1 (8.15%) and lower than that of activated carbon (22.39%) (Figure 12a and Table 1).  
Figure 10: Water vapor physisorption isotherms (298 K) obtained for (**a**) C-1 and (**b**) C-1-F. Solid and open symbols denote adsorption and desorption, respectively.  
Figure 11: FT–IR spectra of C-1 (black) and C-1 after water vapor dynamic adsorption under 20% relative humidity conditions (red).  
Figure 12: Dynamic adsorption capacity of C-1, C-1-F, and activated carbon for DMMP at 305 K under (**a**) dry, (**b**) 20% relative humidity and (**c**) 60% relative humidity conditions. M: relative weight increase.  
The adsorption capacity was further analyzed based on the BET specific surface area and pore volume of the synthesized materials. As shown in Table 1, C-1 had the highest total pore volume but the lowest BET surface area, indicating its higher mesoporosity compared to C-1-F. These differences could be attributed to the -F group in C-1-F, which was introduced into the mesoporous channel of C-1, thus forming more micropores and increasing the specific surface area of C-1-F. Based also on the law of volume change between micropores and mesopores, the adsorption capacity of DMMP was positively related with the micropore volume of C-1-F, further confirming its higher DMMP adsorption capacity compared to C-1. Moreover, the strongly electronegative nature of F can result in the formation of electrostatic repulsive interactions between the F atoms with F atoms or any negatively charged species [37; 38; 39; 40], which may be a factor for its high adsorption capacity for C-1-F.  
The effect of water vapor on the adsorptive performance of materials was also explored (Figure 12b). For increasing the relative humidity to 20%, C-1-F and activated carbon has nearly unchanged adsorption capacity as that under dried conditions (Table 1). Nonetheless, C-1 with a 2.22% adsorption capacity changing indicates the water vapor does affect the adsorption capacity of C-1 materials. As the relative humidity increases to 60%, the effect of water vapor on the adsorption performance of C-1-F and activated carbon increases. However, the sample is still able to exhibit high adsorption capacity (Figure 12c and Table 1).