Role of UV irradiation of Nafion membranes on ionic groups responsible for proton conduction and mechanical strength: A FTIR spectroscopic analysis

Tumor Cell Targeting and Responsive Nanoplatform for Multimodal-Imaging Guided Chemodynamic/Photodynamic/Photothermal Therapy toward Triple Negative Breast Cancer

“…As depicted in Figure S2, the absorption peaks of HA-ICG-Fe-PDA at 3440 cm –1 , 2925 cm –1 , 1638 cm –1 , 1600 cm –1 , 1385 cm –1 , 1350 cm –1 were assigned as −OH/–NH, −CH, −CO, −CC, −OH, and C–O bonds, respectively. The characteristic absorption bands of both −SO 3 H (1080–1000 cm –1 ) and Fe–O (570, 670, and 760 cm –1 ) appeared in the spectrum of HA-ICG-Fe-PDA. In addition, a new peak at 1100 cm –1 representing C–N emerged, which was attributed to the formation of C–N bonds through the Michael addition reaction between HA-ICG and Fe-PDA .…”

The Effect of Salty Environments on the Degradation Behavior and Mechanical Properties of Nafion Membranes

“…As mentioned in Section 3.1.2, proton conduction is an essential property of PEM used in PEMFC, which is achieved by proton-hopping and diffusion mechanisms [22]. It is believed that at low to medium temperatures (25-55 • C), proton hopping predominates, whereas diffusion mechanisms predominate at higher temperatures (85 • C).…”

“…The FTIR spectra of Fenton's tested Nafion membrane show peaks at ~1720, ~1100, ~1020, and ~970 cm −1 associated with C=O stretching, CF 2 stretching, S-O stretching, and C-O-C stretching, respectively (Figure 2) [14,17]. Proton conduction is an essential property of PEM used in PEMFC, which is achieved by proton-hopping and diffusion mechanisms [22]. In the proton-hopping mechanism, a proton hops from one hydrolyzed site (−SO 3 H groups) to another site through the membrane, whereas in the diffusion mechanism, protonated water (H 3 O + ) diffuses across the aqueous medium in response to the electrochemical difference.…”

“…The reduced transmittance peaks of the sulfonic group at higher NaCl concentrations suggest the deterioration of this group. Earlier studies have shown that transmittance peaks of the sulfonic group could be enhanced by crosslinking these groups using UV irradiation, resulting in improved proton hopping, and hence better proton conductivity of the membrane [22,23]. The location and width of the transmittance peak associated with the S-O stretching of the sulfonic acid (SO 3 H) group are sensitive to the presence and type of counteractions due to an induced polarization of S-O dipoles in the sulfonate group by the electrostatic field of the adjacent cation [24].…”

“…The peaks associated with C=O at wavenumber ~1720 cm −1 show an increasing trend with increasing temperature, indicating greater content of this functional group (Figure 5b). The reduced transmittance peaks associated with CF 2 and C-O-C bonds and enhanced peaks associated with C=O indicate the chemical degradation of the membrane, as explained in Section 3.1.2. used in PEMFC, which is achieved by proton-hopping and diffusion mechanisms [22]. It is believed that at low to medium temperatures (25-55 °C), proton hopping predominates, whereas diffusion mechanisms predominate at higher temperatures (85 °C).…”