Novel sulfonated poly (vinyl alcohol)/carboxy methyl cellulose/acrylamide-based hybrid polyelectrolyte membranes

Abstract

Novel polyelectrolytic hybrid membranes are prepared by blending carboxy methyl cellulose (CMC)-polyvinyl alcohol (PVA)-acrylamide (AA). Succinic acid and chlorosulfonic acid (CSA) are employed as crosslinkers and modifiers, respectively. Additionally, carboxylated carbon nanotube (CCNT) and sulfonated activated carbon (SAC) as fillers are used to attain appropriate chemical and mechanical stability for use as polyelectrolyte membranes (PEM). CMC, PVA, and AA are mixed and treated with CSA, CCNT, and SAC in different concentrations. First, CMC/PVA/AA solution is modified using CSA to produce a sulfonated polymeric matrix. Second, a different amount of CCNT or SAC was added as a filler to enhance the ion exchange capacity (IEC), ionic conductivity, and chemical stability. Third, the solution is cast as polyelectrolytic membranes. Chemical interactions between CMC, PVA, AA and other membrane components were confirmed using various characterization techniques such as Raman scattering spectroscopy and Fourier Transform Infrared (FTIR). Furthermore, mechanical strength, methanol uptake, gel fraction, ion exchange capacity (IEC), proton conductivity (PC), chemical and thermal stability were determined as functions of varied membrane modification components. Results reveal that the increase of CSA, CCNT and SAC is leading to increase the IEC values reaching 1.54 mmol/g for (CMC/PVA-4% CSA), 1.74 mmol/g for (CMC/PVA-4%CSA-2%CCNT) and 2.31 mmol/g for (CMC/PVA-4% CSA-2% SAC) comparing to 0.11 mmol/g for non-modified CMC/PVA/AA membrane. Sequentially, the proton conductivity value is changed from 1 × 10–3 S/cm in non-modified CMC/PVA/AA membrane to 0.082 S/cm for (CMC/PVA-4% CSA), 0.0984 S/cm for (CMC/PVA-4%CSA-2%CCNT) and 0.1050 S/cm for (CMC/PVA-4% CSA-2% SAC). Such results enhance the potential feasibility of modified CMC/PVA/AA hybrid as polyelectrolytic membranes.

Development of Sulfonated Poly(vinyl alcohol)/MoS2-Based Robust Composite Proton Exchange Membranes with Higher Selectivity

“…Furthermore, the gel fraction analysis was performed to find out the un-cross-linked membrane components and provides an estimation of the cross-linking density of the membranes. The results showed that about 76 ± 3% of gel fraction percentage was obtained for SPVA/MoS 2 -0.3% membranes due to increased cross-linking density from sulfonation . Sulfonation introduced more -SO 3 H groups attached to the polymer chains in the membrane.…”

“…It is known that the transport of protons across the membrane depends on a vehicular (migration of hydrated protons, H 3 O + ) or Grotthuss (proton hopping) mechanism using bound water present in the membrane. Protons in the form of hydronium ions (H 3 O + ) get transported throughout the membranes via the water molecules present in them. , PVA-based membranes have high water uptake due to the hydrophilic nature of PVA. However, the cross-linked PVA shows lower water uptake with increasing cross-linking density. , The water uptake behavior of pristine and composite membranes for a 24 h study has been shown in Figure d.…”

“…Protons in the form of hydronium ions (H 3 O + ) get transported throughout the membranes via the water molecules present in them. 26,35 PVA-based membranes have high water uptake due to the hydrophilic nature of PVA. However, the cross-linked PVA shows lower water uptake with increasing cross-linking density.…”

“…Additionally, carboxylated carbon nanotubes (CCNTs) and sulfonated activated carbon (SAC) were employed as fillers in different concentrations to improve the mechanical and chemical stabilities of the membranes. Among all of the hybrid membranes, CMC/PVA-4%CSA-2%SAC exhibited the best value of 105 mS/cm proton conductivity . A CPEM based on PVA/SiO 2 containing 5–25 wt % of sulfosuccinic acid (SSA) was investigated for proton conductivity and methanol permeability.…”

“…Among all of the hybrid membranes, CMC/PVA-4%CSA-2%SAC exhibited the best value of 105 mS/cm proton conductivity. 35 A CPEM based on PVA/SiO 2 containing 5−25 wt % of sulfosuccinic acid (SSA) was investigated for proton conductivity and methanol permeability. In this membrane, SSA acts as a cross-linking agent as well as a donor of the hydrophilic −SO 3 H group.…”