https://orbit.dtu.dk/files/4351774/2009%20PBI%20review%20Progress%20in%20Polymer%20Science%2034,%205,%20449-477.pdf

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Zeolitic imidazolate frameworks (ZIFs) represent a new and special class of metal organic frameworks comprised of imidazolate linkers and metal ions, with structures similar to conventional aluminosilicate zeolites Their intrinsic porous characteristics, abundant functionalities as well as exceptional thermal and chemical stabilities have led to a wide range of potential applications for various ZIF materials Explosive research activities ranging from synthesis approaches to attractive applications of ZIFs have emerged in this rapidly developing field in the past 5 years In this review, the development and recent progress towards different synthesis strategies to generate both powder and membrane/film-based ZIF materials are analysed and summarised Their attractive and potential applications in gas separation, catalysis, sensing and electronic devices, and drug delivery in the past years are discussed and reviewed In addition, the prospects and potential new development of ZIF materials are presented

Zeolitic imidazolate framework materials: recent progress in synthesis and applications

Membrane gas separation is a mature and expanding technology. However, the availability of better membrane materials would promote faster growth. In this Perspective we analyze the state of the art of membrane materials, including polymers and hybrid materials, as well as the current issues and barriers, and finally, we outline future research directions in membrane science. Development of new membrane materials for large scale separations will rely on a multidisciplinary approach that embraces the broad fields of chemical and materials engineering, polymer science, and materials chemistry.

http://pubs.acs.org/doi/pdf/10.1021/acs.macromol.7b01718

50th Anniversary Perspective: Polymers and Mixed Matrix Membranes for Gas and Vapor Separation: A Review and Prospective Opportunities

Recent developments on ion-exchange membranes and electro-membrane processes.

The development of high-temperature PEM fuel cells (working at 150–200 °C) is pursued worldwide in order to solve some of the problems of current cells based on Nafion® (CO tolerance, improved kinetics, water management, etc.). Polybenzimidazole membranes nanoimpregnated with phosphoric acid have been studied as electrolytes in PEMFCs for more than a decade. Commercially available polybenzimidazole (PBI) has been the most extensively studied and used for this application in membranes doped with all sorts of strong inorganic acids. In addition to this well-known polymer we also review here studies on ABPBI and other polybenzimidazole type membranes. More recently, several copolymers and related derivatives have attracted many researchers' attention, adding variety to the field. Furthermore, besides phosphoric acid, many other strong inorganic acids, as well as alkaline electrolytes have been used to impregnate benzimidazole membranes and are analyzed here. Finally, we also review different hybrid materials based on polybenzimidazoles and several inorganic proton conductors such as heteropoly acids, as well as sulfonated derivatives of the polymers, all of which contribute to a quickly-developing field with many blooming results and useful potential which are the subject of this critical review (317 references).

Proton-conducting membranes based on benzimidazole polymers for high-temperature PEM fuel cells. A chemical quest

Wholly aromatic polybenzimidazoles were synthesized from aromatic tetraamines and difunctional aromatic acids and characterized as new thermally stable polymers. The melt polycondensation of aromatic tetraamines and the diphenyl esters of aromatic dicarboxylic acids was developed as a general procedure of wide applicability. Polybenzimidazoles containing mixed aromatic units in the chain backbone were prepared from 3,3′-diaminobenzidine, 1,2,4,5-tetraaminobenzene and a variety of aromatic diphenyl dicarboxylates. Phenyl 3,4-diaminobenzoate could also be polymerized by melt condensation to give poly-2,5(6)-benzimidazole. The polymers were characterized by a high degree of stability, showing great resistance to treatment with hydrolytic media and an ability to withstand continued exposure to elevated temperatures. Most of the polymers were infusible, but some had melting points above about 400°C. Many of the polymers exhibited no change in properties on being heated to 550°C. and showed a weight loss of less than 5% when heated under nitrogen for several hours to 600°C. The polymers were soluble in concentrated sulfuric acid and formic acid, producing stable solutions. Many of the polymers were soluble in dimethyl sulfoxide and some also in dimethylformamide. The inherent viscosities of a number of polymers in 0.5% dimethyl sulfoxide solution ranged from approximately 0.4 to 1.1. The higher polymers could be cast into stiff and tough films from formic acid and dimethyl sulfoxide solutions.

Vogel Herward A

Papers

Polybenzimidazoles, new thermally stable polymers

Verfahren zur Herstellung von hochmolekularen cyclischen Polybenzimidazolen