Polyelectrolyte Complexes of Chitosan and Poly(acrylic acid) As Proton Exchange Membranes for Fuel Cells

Abstract

Ionically cross-linked polyelectrolyte complex (PEC) membranes of cationic chitosan (CS) and anionic poly(acrylic acid) (PAAc) were synthesized and assessed for applicability in fuel cells. CS and PAAc were blended in different weight ratios and the resulting membranes were posttreated to enable the formation of the polyelectrolyte complex. The ionic cross-linking occurring on blending the polyelectrolytes excludes the need of using other cross-linking agents. These membranes were extensively characterized for morphology, their intermolecular interactions, thermal stability, and physicomechanical properties using SEM, FTIR, DSC, sorption studies, and tensile testing, respectively. Methanol permeability and proton conductivity were estimated and compared with respective values for Nafion 117. PEC membranes exhibited high ion exchange capacity (IEC), high proton conductivity, low methanol permeability, and adequate thermal and mechanical stability. Among the blends synthesized, the membrane blend with 50 wt % of CS and 50 wt % of PAAc, was identified as ideal for direct methanol fuel cell (DMFC) applications as it exhibited low methanol permeability (3.9 × 10-8 cm2/s), excellent physicomechanical properties and comparatively high proton conductivity (0.038 S·cm-1). Above all, the cost-effectiveness and simple fabrication technique involved in the synthesis of such PECs makes their applicability in DMFC quite attractive.

Polyelectrolytes with sulfonic acid groups useful in the synthesis and stabilization of Au and Ag nanoparticles

“…The polyelectrolytes have found uses in a wide number of technical applications. These include ultrafiltration, [1][2][3] paper-making, wastewater treatment, [4][5][6] food industry, [7][8][9] biomaterials, [10][11][12][13][14][15][16] fuel cells [17][18][19][20][21][22][23] and nanotechnology, [24][25][26][27] just to mention a few. In all these application, the ionic groups or the ionic exchange process of polyelectrolytes is very important.…”

Self-standing chitosan films as dielectrics in organic thin-film transistors

“…Chitin appears in nature as ordered crystalline microfibrils forming structural components of the exoskeleton of crustacean and insects and in the cell walls of fungi and algae [4,5]. In view of its properties, like excellent film-forming ability, biocompatibility and biodegradability [4] chitosan and derivatives have been used in biomedical applications, such as gene delivery, biosensors [6] and also as proton exchange membranes [7]. These applications offer the prospects for the fabrication of biocompatible devices that could operate in biologically relevant media (for instance for smart sensing and preventive medical care), an area that is attracting an increasing attention [8].…”

Lab-on-fiber optofluidic platform for in situ monitoring of drug release from therapeutic eluting polyelectrolyte multilayers

“…After the release of GS from the thin film, there is strong ionic interactions between CHI and PAA including (i) ionic cross-linking between ammonium ion (NH 3+ ) of CHI and carboxylateion (COO -) of PAA, (ii) hydrogen bonding between H + of carboxylic group of PAA and OH -of CHI, and (iii) hydrogen bonding between H + of CHI and OH -of carboxylic group of PAA. These complex interactions ensure adequate thermal and mechanical stability of the blend of CHI and PAA as demonstrated in an early report [33]. Taken as a whole, the initial drug burst release is due predominantly to large concentration gradient between the drug-eluting coating and the flowing medium.…”