No abstract

Review is dedicated to discussion of different types of proton-exchange membranes used in fuel cells (FC). One of the most promising electrolytes is polymer electrolyte membrane (PEM). In recent years, researchers pay great attention to various non-fluorinated or partially fluorinated hydrocarbon polymers, which may become a real alternative to Nafion. Typical examples are sulfonated polyetheretherketones, polyarylene ethers, polysulphones, polyimides. A class of polyimides-based hydrocarbon proton-exchange membranes is separately considered as promising for widespread use in fuel cell, such membranes are of interest for our further experimental development.

This review describes main types of organic polymers, which are now widely used and are the most resistant to ionizing radiation. It presents modern approaches to creation of radiationshielding composite materials based on polymer matrix and various types of fillers. It also discusses the efficiency of sizes of fillers' micro-and nanoparticles in terms of improving radiation resistance of organic polymer materials.

Azomethine ylides have been generated from aromatic aldimines of -amino acid methyl esters under treatment with LiBr/Et 3 N and trapped with tert-butyl acrylate yielding racemic orthogonally protected cis-5-arylpyrrolidine-2,4-dicarboxylates regio-and stereo-selectively in high yields. Subsequent N-methylation and deprotection of 4-carboxylic group of cycloaddition products led to novel prolineglutamate cis-chimeras with substituents at 2 and 5 positions of pyrrolidine scaffold.

A series of polyimide composites reinforced with different loadings of silicon carbide (SiC) nanoparticles are prepared by in-situ polymerization technique. The polyimide (PI) matrix resin is derived from 4,4'-oxydianiline (4,4'-ODA) and pyromellitic dianhydride (PMDA). The dispersions of SiC nanoparticles are prepared via ultrasonic irradiation or mechanical homogenization. In this method, the SiC nanoparticles are dispersed in diamine solution followed by polymerization with dianhydride. The composites obtained under sonication were found to have lower thermal properties than composites prepared under homogenization.