@article {4070,
	title = {Polybenzimidazoles containing heterocyclic benzo[c]cinnoline structure prepared by sol-gel process and acid doping level adjustment for high temperature PEMFC application},
	volume = {182},
	year = {2019},
	note = {n/a},
	month = {2019},
	pages = {121814},
	abstract = {<p>Polybenzimidazoles containing heterocyclic benzo[c]cinnoline structure are synthesized from 3,8-benzo[c]cinnoline dicarboxylic acid, terephthalic acid and 3,3'-diaminobenzidine. Their membranes are prepared by sol-gel process, involving the conversion of polymer solution in polyphosphoric acid to phosphoric acid. The acid doping levels of the as-prepared membranes increase as the contents of benzo[c]cinnoline increase, indicating good interaction between phosphoric acid and benzo[c]cinnoline structure. The as-prepared membranes with high acid doping levels might lead to the dissolution of membranes in phosphoric acid at temperature higher than 120 {\textdegree}C. A new method is proposed to adjust acid doping levels by immersing the as-prepared membranes in diluted phosphoric acid solutions of various concentrations. The adjusted membranes (acid doping levels around 30 PA RU-1) exhibit enhanced mechanical properties with tensile strength in the range of 4.1{\textendash}5.2 MPa. The proton conductivity of adjusted membranes maintain at 0.15{\textendash}0.17 S cm-1 at 160 {\textdegree}C under ambient atmosphere without humidification. The single cells based on the adjusted membranes exhibit open circuit voltages and peak power densities from 0.89 to 0.91 V and 691{\textendash}1253 mW cm-2 at 160 {\textdegree}C, respectively. Compared to other polybenzimidazole membranes prepared by sol-gel process, the adjusted polybenzimidazoles show higher mechanical strength and better single cell performance.</p>
},
	keywords = {Benzo[]cinnoline, Fuel cell, Proton exchange membrane, Sol-gel process},
	isbn = {0032-3861},
	url = {http://www.sciencedirect.com/science/article/pii/S0032386119308201},
	author = {Chen, Jyh-Chein and Hsiao, You-Rong and Liu, Yin-Cheng and Ping-Yen Chen and Kuei-Hsien Chen}
}
