Artificial ion-exchange and other charged membranes, such as biomembranes, are self-organizing nanomaterials built from macromolecules. The interactions of fragments of macromolecules results in phase separation and the formation of ion-conducting channels. The properties conditioned by the structure of charged membranes determine their application in separation processes (water treatment, electrolyte concentration, food industry and others), energy (reverse electrodialysis, fuel cells and others), and chlore-alkali production and others. The purpose of this review is to provide guidelines for modeling the transport of ions and water in charged membranes, as well as to describe the latest advances in this field with a focus on power generation systems. We briefly describe the main structural elements of charged membranes which determine their ion and water transport characteristics. The main governing equations and the most commonly used theories and assumptions are presented and analyzed. The known models are classified and then described based on the information about the equations and the assumptions they are based on. Most attention is paid to the models which have the greatest impact and are most frequently used in the literature. Among them, we focus on recent models developed for proton-exchange membranes used in fuel cells and for membranes applied in reverse electrodialysis.

In this work, we explore the influence of soft segment structure on the crystallinity and phase separation of semicrystalline multi-block thermoplastic polyurethanes (TPUs) based on poly(butylene adipate) diol, polycaprolactone diol, and their mixture. According to thermal and structural analyses, the crystal growth rate and degree of crystallinity decrease with an increase in the PCL/PBA ratio and reach a minimum at the equimolar composition of polyesters. A reduction in crystal phase content leads to an improvement in elastomeric behavior. TPU samples with high PCL content demonstrate enhanced crystallinity but a lower melting temperature compared to TPU with PBA crystals. Crystallization of TPU below room temperature results in an enhancement of total crystallinity and a change in the phase composition of the PBA block. The difference in semicrystalline morphology and crystallization kinetics can be explained by the efficiency of phase separation and the density of hydrogen bonding between soft and hard segments. Our findings show that the ratio of the two crystallizable polyesters, combined with the choice of crystallization temperature, allows for independent control over the melting temperature and the overall degree of crystallinity of the TPUs. This significantly impacts the mechanical characteristics of the materials. The effect of adding a second crystallizable polyester on the crystallization behavior, phase composition, and mechanical properties of TPU is discussed for the first time.

A new multi-blocked polyurethane-based thermoplastic elastomer was synthesized and characterized. A correlation between the supramolecular structure and mechanical properties was found.