ИСТИНА

Electrochemical power sources (EPS) have found a growing number of applications in various areas of human life. Despite their rising popularity and, as a consequence, a large amount of research, there are still plenty of unsolved problems. The centerpiece of the majority of EPS is an ion-conducting membrane, and its properties are mainly responsible for the performance of an EPS. The goal of the present investigation is to study the problem of microphase separation (self-assembly on micro- and non-scale) in polyelectrolyte melts; such systems are the most promising candidates for creating new generation ion-conducting membranes. The problem of microphase separation in polyelectrolyte copolymer blends has received massive attention during the last years due to the ability of such copolymers to form nonconventional structures. However, due to the overall complexity of the system there is no complete picture of the phase behavior even for the case of linear polyelectrolyte diblock-copolymers; moreover, the presence of two types of very distinct interactions (volume and electrostatic) makes it hard to develop a theory capturing all the relevant effects. We present a mesoscopic simulation of the phase behavior of melts of diblock-copolymers with one charged block with charges located on the chain backbone or on short spacers; such systems are essentially a model of polymerized ionic liquid (PIL) block copolymers. We use a well known dissipative dynamics method (DPD) which has been proven to be an excellent choice for simulation of melts of uncharged copolymers; the implementation of Coulombic interactions necessary to simulate polyelectrolyte melts is discussed. A special force type is required to correctly take into account the electrostatic interactions at all the relevant scales as well as to prevent the overlapping of oppositely charged beads. The phase behavior is studied for a number of chain compositions and interaction strengths; at low dielectric constants, the charge correlation effects cause the charged block with counterions to form a condensed phase even if the blocks are miscible (i.e. Florry-Huggins interaction parameter χ=0). For the simplest case of linear copolymer conventional phases (lamellae, hexagonally packed cylinders etc.) are obtained, while the presence of short spacers promotes the formation of inverted structures which have great potential as membranes for various applications. We also showed that due to the presence of the counterions in the system, the obtained structures have some unique properties.