(376b) Synthesis and Characterization of Novel Sulfonated Amine Block Copolymers for Direct Methanol Fuel Cells

Direct methanol fuel cells (DMFC) have continued to gain traction over past years as a promising alternative source of energy. The efficiency of the DMFC depends on the composition of the proton exchange membrane (PEM) used. Although Nafion is currently the state of the art PEM, it exhibits some disadvantages such as permeability to fuels and high cost. In order to overcome these limitations, there is a considerable interest in synthesizing PEMs based on aromatic polymers because of their availability and easy modification.

In this work, atom transfer radical polymerization (ATRP) was used to synthesize styrene-based amine block copolymers for DMFC applications. The block copolymer was then sulfonated by chemical grafting with pendants sulfobutyl groups onto the polymer structure. This method has been shown to generate PEMs with better proton conductivity and water absorption, than PEMs with sulfonic groups bonded on aromatic rings. Properties of the resulting membranes were determined as a function of amine block composition and sulfonation level. A series of materials characterization techniques (e.g., FT-IR, AFM, SAXS) was utilized to understand the interaction between sulfonic and amine groups in the polymer matrix and their effect on the morphology and transport properties of the membranes for fuel cells.