Polystyrene, polymer electrolytes

Biichi, F. N., Gupta, B., Haas, O. and Scherer, G. G. 1995. Study of radiation-grafted FEP-g-polystyrene membranes as polymer electrolytes in fuel cells. Electrochimica Acta 40 345-353. 

Solution polymerization is used for the manufacture of polyethylene, polypropylene, and polystyrene, but by far the most widely used process for polystyrene and PVC is suspension polymerization. In the latter process (also known as bead, pearl, or granular polymerization because of the form in which the final products may be obtained), the monomer is dispersed as droplets (0.01-0.05 cm in diameter) in water by mechanical agitation. Various types of stabilizers, which include water-soluble organic polymers, electrolytes, and water-insoluble inorganic compounds, are added to prevent agglomeration of the monomer droplets. Each monomer droplet in the suspension constitutes a small bulk polymerization system and is transformed finally into a solid bead. Heat of polymerization is quickly dissipated by continuously stirring the suspension medium, which makes temperature control relatively easy. 

It was mentioned that the properties of the polymer film depend on the type of anion. In Figure 11.20, another RC versus potential diagram is shown for a polypyrrole film prepared by anodic oxidation in a polystyrene-sulfonate electrolyte. The large ion cannot... 

Several non-fluorinated alternative polymers have been proposed for DAFC, mainly based on sulfonated ionomers with an aromatic or aliphatic hydrocarbon skeleton [7], Kim and Pivovar [4] have reported the number of DMFC alternative membranes papers appearing in open hterature for years 1994—2004, showing that polyarylenes, polyvinyl alcohols, grafted and block polystyrenes copolymers, and polyimides were among the most studies polymer electrolytes. In view of the dramatic increase in the number of publications since 2005 (see Fig. 6.1), the trends have changed, as shown in Table 6.1, which sununaiized the publications in open literature for the period 2005-2012, as compared to the previous period. 

A polymer electrolyte is made from (1) supported on a polymer such as polystyrene. The film shows high proton condensation in the absence of water, thereby eliminating the need for a humidifier for a fuel cell gas. " ... 

Suksawad, R, Kosugi, K., Yamamoto, Y, Aka-bori, K., Kuroda, H., and Kawahara, S. (2011). Polymer electrolyte membrane with nanomatrix channel prepared by sulfonation of natural rubber grafted with polystyrene. J. Appl. Polym. Set. 122,2403-2414. 

During these programs, PME fuel cells and electrolyzers were developed. These first solid membranes were made of sodium polystyrene sulfonate, and would be replaced by Nafion, which was discovered by DuPont in the same decade. Thus, it was in 1966 that the very first solid-polymer electrolyte (SPE) electrolyzer was built by General Electric (GE) for Project GEMINI to produce oxygen on board the spacecraft. 

Figure I.6a also reveals the timeline of milestones in fuel cell design. The leftmost curve is the performance curve of the first practical H2/O2 fuel cell, built by Mond and Langer in 1889 (Mond and Langer, 1889). The electrodes consisted of thin porous leafs of Pt covered with Pt black particles with sizes of 0.1 lam. The electrol)de was a porous ceramic material, earthenware, that was soaked in sulfuric acid. The Pt loading was 2 mg cm and the current density achieved was about 0.02 A cm at a fuel cell voltage of 0.6 V. The next curve in Figure I.6a marks the birth of the PEFC, conceived by Grubb and Niedrach (Grubb and Niedrach, 1960). In this cell, a sulfonated cross-linked polystyrene membrane served as gas separator and proton conductor. However, the proton conductivity of the polystyrene PEM was too low and the membrane lifetime was too short for a wider use of this cell. It needed the invention of a new class of polymer electrolytes in the form of Nafion PFSA-type PEMs to overcome these limitations.

Fig. 5 Projected life capabilities for certain polymer electrolyte membrane (PEMs) in Hj/O fuel cell stacks (210-480kPa 50-300mA cm fully hmnidified grafted polystyrene sulfonic acid (PSSA), grafted trifluoromethansulfonic acid (TFSA), and Nafion, (1,250 to 1,1(X) equivalent weight) nongrafted TFSA (400-600 equivalent weight) 175-300- im PEM thickness 4-8 mg Pt cm each side) (LaConti et al. 2005)...

---