Synthesis and characterization of modified κ-carrageenan for enhanced proton conductivity as polymer electrolyte membrane

Abstract

Polymer electrolyte membranes based on the natural polymer κ-carrageenan were modified and characterized for application in electrochemical devices. In general, pure κ-carrageenan membranes show a low ionic conductivity. New membranes were developed by chemically modifying κ-carrageenan via phosphorylation to produce O-methylene phosphonic κ-carrageenan (OMPC), which showed enhanced membrane conductivity. The membranes were prepared by a solution casting method. The chemical structure of OMPC samples were characterized using Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR) spectroscopy and 31P nuclear magnetic resonance (31P NMR) spectroscopy. The conductivity properties of the membranes were investigated by electrochemical impedance spectroscopy (EIS). The characterization demonstrated that the membranes had been successfully produced. The ionic conductivity of κ-carrageenan and OMPC were 2.79 × 10−6 S cm-1 and 1.54 × 10−5 S cm-1, respectively. The hydrated membranes showed a two orders of magnitude higher ionic conductivity than the dried membranes.

Effect of Active Site Modification towards Performance Enhancement in Biopolymer κ-Carrageenan Derivatives

“…The peak observed at 920 cm −1 represents C–O–C in 3,6-anhydrous-D-galactose. These peaks were very similar to the findings reported in the literature [ 4 , 26 , 27 ]. Meanwhile, the appearance of a new peak was observed at 1068 cm −1 for succinyl κ-carrageenan, representing the vibration of the C–O bond in the ester of the succinyl group [ 28 ].…”

“…The pattern of current research focuses on biopolymer polysaccharides as sensors, polymer electrolytes, and biological applications through the enhancement of active sites such as cellulose, chitosan, and carrageenan [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Modification of active sites in a biopolymer polysaccharide structure is vital for the enhancement of the polysaccharide’s performance.…”

“…Carrageenan is an example of a biopolymer polysaccharide. Carrageenan is a natural biopolymer sulfated polysaccharide that consists of an alternating and repeating unit of four linked 3,6-anhydrous-α-D-galactose (D-unit) and three linked β-D-galactose (G-unit) components, which can be extracted from red seaweeds [ 4 , 18 ]. There are three primary forms of carrageenan: lambda- (λ), iota- (ι), and kappa (κ)-carrageenan.…”

Physically Crosslinked Poly (Vinyl Alcohol)/Kappa-Carrageenan Hydrogels: Structure and Applications

“…The diffractogram of pure κ-carrageenan reveals the presence of an amorphous hallo centered at 2θ = 21.8 • and a weak diffraction contribution at 26.5 • , which was ascribed in previous studies to inorganic trace impurities. The last peak does not appear in the diffractograms of the PVA/CAR mixtures, probably due to the dilution effect [41].…”

Architectural engineering of bioelectrochemical systems from the perspective of polymeric membrane separators: A comprehensive update on recent progress and future prospects

“…Relevant estimations for various materials can be found in the paper of Dhar and Lee [15] and it can be drawn that further efforts have to be invested to attain the reduction of costs [18]. In this aspects, apart from artificially designed and synthetized polymers, naturally-occurring polymers and relatively cheap materials such as cotton fabric combined with PVA-PVDF [189], gelatin and alginate [190], agar [191], rubber [192], biodegradable bag [193], cellulose-derivative [121], carrageenan [194], ceramics [68,[195][196][197][198][199], Jcloth (a macroporous filter) [200] have been also employed as membranes/separators with various degrees of success in BES and hence, may present a path in the R&D of membranes/separators for cost reduction purposes.…”