@article { ISI:000272871400006,
	title = {N-substitution of polybenzimidazoles: synthesis and evaluation of physical properties},
	journal = {European Polymer Journal},
	volume = {45},
	number = {12},
	year = {2009},
	month = {DEC},
	pages = {3363-3371},
	publisher = {PERGAMON-ELSEVIER SCIENCE LTD},
	address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND},
	abstract = {<p>Series of N-substituted polybenzimidazoles (PBI) were synthesized using selective alkyl groups with varying bulk and flexibility, viz., methyl, n-butyl, methylene trimethylsilane and 4-tert-butylbenzyl. PBl-I based on 3,3{\textquoteright}-diaminobenzidine (DAB) and isophthalic acid and PBI-Bul based on DAB and 5-tert-butyl isophthalic acid were chosen for N-substitution. Structural characterizations of substituted polymers by FT-IR and (1)H NMR revealed elimination of hydrogen bonding. Evaluation of their physical properties revealed that N-substitution rendered better solvent solubility in common organic solvents, more open polymer matrix, but reduced thermal properties in comparison to their respective parent PBI. 4-tert-butylbenzyl, methylene trimethylsilane or n-butyl group substituted polymers were soluble even in chlorinated solvents (CHCl(3) and TCE). Substantial variations in gas permeability of inert gases, He and Ar and attractive P(He)/P(Ar) selectivity, especially after methyl group substitution depicted potential of these materials for gas separation. (C) 2009 Elsevier Ltd. All rights reserved.</p>},
	keywords = {Gas permeation, hydrogen bonding, N-Substitution, Polybenzimidazole},
	issn = {0014-3057},
	doi = {10.1016/j.eurpolymj.2009.10.006},
	author = {Kumbharkar, Santosh C. and Kharul, Ulhas K.}
}
