ISSN 1995-0780, Nanotechnologies in Russia, 2011, Vol. 6, Nos. 7–8, pp. 476–482. © Pleiades Publishing, Ltd., 2011. Original Russian Text © I.N. Veselov, P.V. Komarov, 2011, published in Rossiiskie Nanotekhnologii, 2011, Vol. 6, Nos. 7–8. 476 INTRODUCTION In long-term prospects, low-temperature hydro- gen–oxygen fuel cells with polymer electrolytes (ion- omers) are positioned as an alternative to traditional autonomous sources of electric energy for use in por- table electron accessories, means of transport, and dif- ferent household devices. A polymer ion-exchange membrane is a key component of such fuel cells. It provides the barrier functions between the fuel and oxidizer flows and serves as an isolator between elec- trodes and a proton conductor [1]. Currently, mem- branes based on perfluorinated polymers of the Nafion group (Nafion® by DuPont) are the most common- place due to their high ion conductivity (0.9–12 × 10 2 Cm/cm) [1–3], mechanical strength, chemical dura- bility (to both hydrolysis and oxidation), and thermo- stability. However, such membranes are very expensive ($800 per 1 m 2 ) and their production is toxic. These drawbacks are the main factors hampering the wide usage of membranes based on perfluorinated poly- mers. At present, different types of synthetic polymer electrolytes and composites on their basis, which can be used as a cheap alternative to Nafion, were studied [3–5]. Sulfonated poly(ether ether ketones) (SPEEK) are singled out among promising ionomers, since they have good mechanical properties and high chemical stability and durability [3–6]. Polymers of this class are relatively cheap in production, although they do not have sufficiently high proton conductivity (0.02– 3.9 × 10 –2 Cm/cm) [3–5]. The highest conductivity values were obtained only at high degrees of sulfona- tion (DS) DS > 0.7. However, in this case, SPEEK becomes water-soluble and it is necessary to introduce cross links between the polymer chains to give mechani- cal stability to a membrane [3]. The transport properties of ionomers are due to the features of their chemical structure. The microphase separation takes place due to the presence of hydro- phobic (nonsulfonated) and hydrophilic (sulfonated) links in a polymer under the effect of water. As a result of this process, a coupled net of water channels being ion conductors is formed. Their average diameter in the cross section is ~5 nm. Hydrophobic segments of the polymer chains form a skeletal framework, which fills the space between channels and yields the mechanical stability of membranes. Hydrophilic seg- ments form the walls of the channels. The structure of channels depends on the form of ionomer macromolecules, features of the distribution of the sulfonic groups, and the volume of water absorbed by the membrane. A water amount in the membrane is often characterized by the parameter λ. It is equal to the number of water molecules per one sulfonic group. With a decrease in λ, channels are compressed and the ionomer conductivity decreases. Below the percolation threshold λ*, the net of water channels is broken and falls into separate isolated water domains. This automatically means that the membrane is no longer the ion conductor. The lower the λ* values are at which the coupled net of channels remains, the better the performance of membranes under the conditions of large water loss (which are implemented with temperature) is. Effect That the Chemical Structure of Ionomer Has on the Morphology of Water Channels of Ion-Exchange Membranes: A Mesoscopic Simulation I. N. Veselov a and P. V. Komarov a, b a Tver State University, ul. Zhelyabova 33, Tver, 170100 Russia b Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova 28, Moscow, 119991 Russia e-mail: pv_komarov@mail.ru Received January 25, 2011; in final form, April 7, 2011 Abstract—The effect that the features of the chemical structure of oligomer chains of an ionomer has on the morphology of water channels formed in ion exchange membranes based on sulfonated polyether ether ketones (SPEEK) has been studied by the dynamic density functional theory. The characteristics of mem- branes based on oligomeric SPEEK chains with the regular, partially distorted, and completely random dis- tribution of hydrophobic and hydrophilic monomers have been compared. The results indicate that ionomer membranes based on regular multiblock AB copolymers can perform better than membranes based on multi- block copolymers with a random chain structures. DOI: 10.1134/S1995078011040148