Enhanced Ion Cluster Size of Sulfonated Poly (Arylene Ether Sulfone) for Proton Exchange Membrane Fuel Cell Application

A successful approach towards enhancement in ion cluster size of sulfonated poly (arylene ether sulfone) (SPAES)-based membranes has been successfully carried out by encapsulating basic pendent branches as side groups. Modified SPAES was synthesized by condensation polymerization followed by bromination with N-bromosuccinamide (NBS) and sulfonation by ring opening reaction. Various molar ratios of branched polyethyleneimine (PEI) were added to the SPAES and the developed polymer was designated as SPAES-x-PEI-y, where x denoted the number of sulfonating acid group per polymer chain and y represents the amount of PEI concentration. Polymer synthesis was characterized by 1H-NMR (Nuclear magnetic resonance) and FT-IR (Fourier-transform infrared spectroscopy) analysis. A cumulative trend involving enhanced proton conductivity of the membranes with an increase in the molar ratio of PEI has been observed, clearly demonstrating the formation of ionic clusters. SPAES-140-PEI-3 membranes show improved proton conductivity of 0.12 Scm−1 at 80 °C. Excellent chemical stability was demonstrated by the polymer with Fenton’s test at 80 °C for 24 h without significant loss in proton conductivity, owing to the suitability of the synthesized hybrid membrane for electrochemical application. Moreover, a single cell degradation test was conducted at 80 °C showing a power density at a 140 mWcm−2 value, proving the stable nature of synthesized membranes for proton exchange membrane fuel cell application.

Structural characterization and photochromic behaviour of a novel compound based on a π-acidic naphthalene diimide derivative and a double hydroxide-bridged dinuclear AlIII aqua ion cluster

Noncovalent interactions, such as π–π stacking interactions, C—H...π interactions and hydrogen bonding, are important driving forces for self-assembly in the construction of functional supermolecules and materials, especially in multicomponent supramolecular systems. Herein, a novel compound based on a π-acidic naphthalene diimide derivative and a double hydroxide-bridged dinuclear Al3+ aqua ion cluster, namely bis[N,N′-bis(2-sulfonatoethyl)-1,4,5,8-naphthalene diimide] di-μ-hydroxido-bis[tetraaquaaluminium(III)] tetrahydrate, (C18H12N2O10S2)2[Al2(OH)2(H2O)8]·4H2O, was obtained using the above-mentioned common noncovalent interactions, as well as uncommon lone-pair–π interactions. Functional molecular modules were connected by these noncovalent interactions to generate obvious photochromic properties. The compound was prepared by the self-assembly of N,N′-bis(2-sulfoethyl)-1,4,5,8-naphthalene diimide and Al(NO3)3·9H2O under mixed solvothermal conditions, and was characterized in detail by single-crystal X-ray diffraction, powder X-ray diffraction and FT–IR spectroscopy. The thermal stability and photochromic properties were also investigated; furthermore, in-situ solid-state UV–Vis absorption spectroscopy and electron spin resonance (ESR) were used to clarify the photochromic mechanism.