Chemistry Commons^™

Tailoring Polybenzimidazole Membranes For Enhanced Performance In Electrochemical Devices, Andrew T. Pingitore

Theses and Dissertations

After approximately 15 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). PBI MEAs can operate reliably without complex water humidification hardware and are able to run at elevated temperatures of 120-180 OC due to the physical and chemical robustness of PBI membranes. These higher temperatures improve the electrode kinetics and conductivity of the MEAs, simplify the water and thermal management of the systems, and significantly increase their tolerance to fuel impurities. Membranes cast by a newly developed polyphosphoric acid (PPA) Process possessed excellent mechanical properties, higher phosphoric acid …

Hydroxy Polybenzimidazoles For High Temperature Fuel Cells And The Solution Polymerization Of Polybenzimidazole, Kayley Fishel

Theses and Dissertations

In this dissertation, two different hompolymers of polybenzimidazole (PBI) containing hydroxyl functional units were synthesized via the PPA Process to produce gel membranes. These polymers and their phosphoric acid doped membranes were characterized to further explore structure-property relationships in functionalized PBI's. Fuel cell performance of the doped membranes was evaluated and compared to previously reported PBI membrane chemistries. Copolymers of p-OH PBI and para-PBI were prepared at five different copolymer compositions to examine the effects of hydroxy content on membrane properties and compared to the respective homopolymers. The reactivity of the hydroxy groups and the formation of phosphate bridges were …

Structure-Property Relationships In Polybenzimidazole Materials For Gas Separation And Fuel Cell Applications, Xin Li

Theses and Dissertations

The central theme of my research lies in the investigation of novel polybenzimidazole (PBI)-based materials for different energy related applications ranging from proton exchange membrane fuel cells (PEMFC) to high temperature gas separation. With the aid of a deeper understanding of the structure-property relationships in this class of materials, a better control on PBI chemistry - from monomer structure to polymer morphology to membrane/film processing method was able to be performed in order to achieve greater performance in targeted applications.

In Chapter 1, the overall background of two energy related applications - fuel cells and gas separation was first introduced …