Proton-Conducting Polymers and Membranes for Fuel Cells-Preparation and Properties

Lina Karlsson

Research output: ThesisDoctoral Thesis (compilation)


The development of new materials for use in fuel cells is of importance for the probable replacement of the combustion engine by this technology in public vehicles in the future. The proton-conducting polymer electrolyte membrane is one of the main components in the fuel cell. The need for improved performance of the proton conducting membrane is large and has led to intensive research worldwide. When new materials are developed, a fundamental understanding of their properties is of importance for the optimization of the material in its application.

In the present work two different series of proton-conducting polymer systems were prepared and studied. The first one was a series of amphiphilic copolymers with sulfonic acid groups synthesized from sulfonated and non-sulfonated acrylamide monomers. The copolymers obtained were characterized by solution and aggregation properties using viscometry, light scattering and atomic force microscopy. It was concluded that the polymers behaved as polyelectrolytes in solution. In solutions with copolymers having a low content of sulfonic acid groups the presence of aggregates was detected. The water absorption properties were investigated in humidified air and the absorption was found to increase approximately linearly with the content of sulfonic acid groups. The effect of the amount of water in the samples and the interaction between the water and the polymer were studied in relation to the proton conductivity. High amounts of water and acid groups generally resulted in a high conductivity above 0 °C, however, at temperatures below 0 °C the state of the water was of greater importance. A high degree of interaction between the water and the polymer, and thus the inability of the water to crystallize, was necessary to reach a high conductivity.

In order to prepare proton conducting membranes, modification of aromatic polymers such as polysulfone and polyphenylsulfone was performed. These materials are thermally, mechanically and chemically stable materials. Short sulfonated spacers were attached to the polymer main chain by lithiation followed by reaction with an electrophile. Both flexible aliphatic and rigid aromatic spacers were used. The modification of these materials resulted in proton conductivities and thermal stabilities in the range of other sulfonated aromatic materials. The water absorption properties were encouraging and some of the materials had a constant water absorption at temperatures above 120 °C. The materials with the most rigid molecular structure showed a constant water absorption to the highest temperatures. In addition, the interaction between the absorbed water and the polymers was high for these materials. This was shown by the inability of the absorbed water to crystallize when analyzed with DSC. These properties indicated that these materials may be useful in fuel cells operated at elevated temperatures and possibly also in direct methanol fuel cells.
Original languageEnglish
Awarding Institution
  • Centre for Analysis and Synthesis
  • [unknown], [unknown], Supervisor, External person
Award date2003 Jun 11
ISBN (Print)91-7422-023-3
Publication statusPublished - 2003

Bibliographical note

Defence details

Date: 2003-06-11
Time: 10:15
Place: Lecture hall C, Centre for Chemistry and Chemical Engineering, Lund Institute of Technology

External reviewer(s)

Name: Rozière, Jacques
Title: Professor
Affiliation: Laboratoire des Agregats Moleculaires et Materiaux Inorganiques, Universite Montpellier II, France


Article: I Preparation and Solution Properties of Amphiphilic Sulfonated Acrylamide CopolymersLina E. Karlsson, Patric Jannasch, and Bengt WesslénMacromolecular Chemistry and Physics, 203 (4): 686-694, 2002

Article: II Water Absorption and Proton Conductivity of Sulfonated Acrylamide CopolymersLina E. Karlsson, Bengt Wesslén, and Patric JannaschElectrochimica Acta, 47 (20):3269-3275, 2002

Article: III Sulfophenylation of Polysulfones for Proton-Conducting Fuel Cell MembranesBenoît Lafitte, Lina E. Karlsson, and Patric Jannasch.Macromolecular Rapid Communication, 23 (15): 896-900, 2002

Article: IV Polysulfone Ionomers for Proton-Conducting Fuel Cell Membranes:1. Sulfoalkylated PolysulfonesLina E. Karlsson and Patric JannaschSubmitted to Journal of Membrane Science, 2003

Article: V Polysulfone Ionomers for Proton-Conducting Fuel Cell Membranes:2. Sulfophenylated Polysulfones and PolyphenylsulfonesLina E. Karlsson and Patric JannaschSubmitted to Journal of Materials Chemistry, 2003

The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Polymer and Materials Chemistry (LTH) (011001041), Department of Chemistry (011001220)

Subject classification (UKÄ)

  • Chemical Sciences

Free keywords

  • Polymer technology
  • solution properties
  • aggregation
  • state of the water
  • sulfonation
  • polyelectrolyte
  • polymer electrolyte
  • ionomer
  • acrylamide copolymer
  • polyphenylsulfone
  • polysulfone
  • water absorption
  • ion exchange membrane
  • proton conductivity
  • Polymerteknik
  • biopolymers


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