Fabrication of Polyelectrolyte Membranes of Pectin Graft-Copolymers with PVA and Their Composites with Phosphomolybdic Acid for Drug Delivery, Toxic Metal Ion Removal, and Fuel Cell Applications

In this study, a simple method for the fabrication of highly diffusive, adsorptive and conductive eco-friendly polyelectrolyte membranes (PEMs) with sulfonate functionalized pectin and poly(vinyl alcohol)(PVA) was established. The graft-copolymers were synthesized by employing the use of potassium persulfate as a free radical initiator from pectin (PC), a carbohydrate polymer with 2-acrylamido-2-methyl-1-propanesulphonic acid (AMPS) and sodium 4-vinylbenzene sulphonate (SVBS). The PEMs were fabricated from the blends of pectin graft-copolymers (PC-g-AMPS and PC-g-SVBS) and PVA by using a solution casting method, followed by chemical crosslinking with glutaraldehyde. The composite PEMs were fabricated by mixing phosphomolybdic acid with the aforementioned blends. The PEMs were successfully characterized by FTIR, XRD, SEM, and EDAX studies. They were assessed for the controlled release of an anti-cancer drug (5-fluorouracil) and the removal of toxic metal ions (Cu2+) from aqueous media. Furthermore, the composite PEMs were evaluated for fuel cell application. The 5-fluorouracil release capacity of the PEMs was found to be 93% and 99.1% at 300 min in a phosphate buffer solution (pH = 7.4). The highest Cu2+ removal was observed at 206.7 and 190.1 mg/g. The phosphomolybdic acid-embedded PEMs showed superior methanol permeability, i.e., 6.83 × 10−5, and 5.94 × 10−5, compared to the pristine PEMs. Furthermore, the same trend was observed for the proton conductivities, i.e., 13.77 × 10−3, and 18.6 × 10−3 S/cm at 30 °C.

Fabrication of Eco-Friendly Polyelectrolyte Membranes Based on Sulfonate Grafted Sodium Alginate for Drug Delivery, Toxic Metal Ion Removal and Fuel Cell Applications

Polyelectrolyte membranes (PEMs) are a novel type of material that is in high demand in health, energy and environmental sectors. If environmentally benign materials are created with biodegradable ones, PEMs can evolve into practical technology. In this work, we have fabricated environmentally safe and economic PEMs based on sulfonate grafted sodium alginate (SA) and poly(vinyl alcohol) (PVA). In the first step, 2-acrylamido-2-methyl-1-propanesulphonic acid (AMPS) and sodium 4-vinylbenzene sulfonate (SVBS) are grafted on to SA by utilizing the simple free radical polymerization technique. Graft copolymers (SA-g-AMPS and SA-g-SVBS) were characterized by 1H NMR, FTIR, XRD and DSC. In the second step, sulfonated SA was successfully blended with PVA to fabricate PEMs for the in vitro controlled release of 5-fluorouracil (anti-cancer drug) at pH 1.2 and 7.4 and to remove copper (II) ions from aqueous media. Moreover, phosphomolybdic acids (PMAs) incorporated with composite PEMs were developed to evaluate fuel cell characteristics, i.e., ion exchange capacity, oxidative stability, proton conductivity and methanol permeability. Fabricated PEMs are characterized by the FTIR, ATR-FTIR, XRD, SEM and EDAX. PMA was incorporated. PEMs demonstrated maximum encapsulation efficiency of 5FU, i.e., 78 ± 2.3%, and released the drug maximum in pH 7.4 buffer. The maximum Cu(II) removal was observed at 188.91 and 181.22 mg.g–1. PMA incorporated with PEMs exhibited significant proton conductivity (59.23 and 45.66 mS/cm) and low methanol permeability (2.19 and 2.04 × 10−6 cm2/s).

Highly Conductive Polyelectrolyte Membranes Poly(vinyl alcohol)/Poly(2-acrylamido-2-methyl propane sulfonic acid) (PVA/PAMPS) for Fuel Cell Application

In this study, chemically cross-linked PVA/PAMPS membranes have been prepared to be used in direct methanol fuel cells (DMFCs). The structural properties of the resultant membrane were characterized by use FTIR and SEM. Additionally, their thermal stability was assessed using TGA. Moreover, the mechanical properties and methanol and water uptake of membrane was studied. The obtained FTIR of PVA/PAMPS membranes revealed a noticeable increase in the intensity of adsorption peaks appearing at 1062 and 1220 cm−1, which correspond to sulfonic groups with the increasing proportion of PAMPS. The thermograms of these polyelectrolyte membranes showed that their thermal stability was lower than that of PVA membrane, and total weight loss gradually decreased with increasing the PAMPS. Additionally, the functional properties and efficiency of these polyelectrolyte membranes were significantly improved with increasing PAMPS proportion in these blends. The IEC of polymer blend membrane prepared using PVA/PAMPS ratio of 1:1 was 2.64 meq/g. The same membrane recorded also a methanol permeability coefficient of 2.5 × 10−8 cm2/s and thus, its efficiency factor was 4 × 105 greater than that previously reported for the commercial polyelectrolyte membrane, Nafion® (2.6 × 105). No significant increase in this efficiency factor was observed with a further amount of PAMPS. These results proved that the PVA:PAMPS ratio of 1:1 represents the optimum mass ratio to develop the cost-effective and efficient PVA/PAMPS blend membranes for DMFCs applications.

Preparation and Chemical Protective Clothing Application of Sulfonated Poly(2,6-dimethyl-1,4-phenyleneoxide)

The preparation of chemical protective clothing (CPC) materials with excellent protective performance and physiological comfort have always been a global challenge. The selective permeability of organic matter and water shown by polyelectrolyte membranes in fuel cells and other applications provides ideas for solving this problem. This research focused on sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a polyelectrolyte membrane material with excellent performance, and carried out different counter-ion substitutions to prepare a series of membrane materials, and their mechanical properties, contact angle, permeability, and selectivity. The performance was tested and compared with Nafion, a typical commercial membrane. The results show that the SPPO membrane has the potential of CPC application and the performance of the membranes can be controlled by the simple method of adjusting the counter-ion exchange of the membrane material.