Synthesis and solubility of poly(N‐methylbenzimidazole) and poly(N‐ethylbenzimidazole): control of degree of alkylation

Abstract

In this paper, synthesis of poly(N‐methylbenzimidazole) (PNMBI) and poly(N‐ethylbenzimidazole) (PNEBI) with various alkylation degrees was achieved by adding enough LiH and controlling the amount of substituting reactant. The degree of substituted methyl or ethyl was determined by elemental analysis. Changes in infrared spectroscopy due to nature and degree of substitution can clearly be found. With the modification of PBI, the solubility of PNMBI and PNEBI is improved significantly. There is no significant change of chemical structure of PNMBI after 0.5 h thermal treatment in both N2 and air at a temperature lower than 250 °C. Compared with PBI, the methanol permeability of PNMBI and PNEBI is a little higher but still of the same order of magnitude. Copyright © 2004 Society of Chemical Industry

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

“…Pu and Liu [113][114][115] prepared poly(Nmethylbenzimidazole) and poly(N-ethylbenzimidazole). Interestingly, when methyl and ethyl groups are introduced on the imidazole moiety, the obtained N-substituted PBI showed high acid-doping levels and therefore high proton conductivity.…”

Understanding ternary poly(potassium benzimidazolide)-based polymer electrolytes

“…Such poly(benzimidazolide)s are strongly nucleophilic and are used as intermediates in the synthesis of Michael addition type crosslinked m-PBI [22] or poly(alkyl/aryl benzimidazolium) ionomers [23][24][25][26].…”

Methylated polybenzimidazole and its application as a blend component in covalently cross-linked anion-exchange membranes for DMFC

“…Other research groups have used the strongly toxic methylation agent methyl iodide (MeI) for the alkylation of imidazole groups (to form anion-exchange groups) [34][35][36][37][38]. It was the intention of this study to substitute MeI with a non-toxic methylation reagent system.…”

“…mPBIOO was used to develop a novel type of mechanically and chemically stable AEM for application in alkaline DMFCs. Studies to date have all methylated PBI precursors using the highly toxic alkylation agent methyl iodide [34][35][36][37][38]. In this study a more facile and "green chemistry" PBI alkylation method is presented, which involves the non-toxic alkylation reagent dimethylcarbonate along with DABCO as the alkylation catalyst (see Figure 1).…”

“…With a focus on application in PEMFCs, Pu et al. investigated methylated and ethylated PBI [35,36]. The usage of alkylated PBI for development of anion-exchange materials was first mentioned (independently) in 2011 by…”