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International audienceNew soluble polyimides were prepared from a series of diamines and a tetracarboxylic dianhydride with a benzhydrol unit, 3,3‘,4,4‘-benzhydrol tetracarboxylic dianhydride (BHTDA), by one-step method polymerization. The diamines containing flexible units, bulky substituents, and/or noncoplanar conformation unit were prepared by the reaction of the corresponding bisphenol precursors and p-chloronitrobenzene, followed by catalytic reduction of the dinitro compounds. The polyimides obtained were soluble in various solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, pyridine, γ-butyrolactone, m-cresol, and even tetrahydrofuran except for polymer PId. The polymers were amorphous and had number-average molecular weight (n) in the range (3.0−10.2) × 104. The glass transition temperatures (Tg) of the polymers ranged from 268 to 341 °C. These polymers exhibited good thermal stability without significant weight loss up to 420 °C. The temperatures at 10% weight loss range from 457 to 524 °C in nitrogen and 449 to 519 °C in air, respectively. The polyimide films were found to be transparent, flexible, and tough. The films had a tensile strength range 72−105 MPa, an elongation range at break of 4−7%, and a Young's modulus range of 2.18−2.85 GP

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Before polymerization, nadimide end-capped polyimide oligomers exist in the endo form. During the cure, an endo-exo equilibrium takes place. This paper discusses the relationship between endo-exo isomerization and the reverse-Diels-Alder reaction of the nadinaide system. As a consequence of the experimental results, an explanation for cyclopentadiene evolution during the polymerization of nadimide systems is given.

This paper discusses the evolution observed in the field of high performance polymers and tries to forecast the future in different domains. The paper is divided into four sections: 1. From the 1960s to the 21st century. 2. What's new in chemistry and why? 3. What could be the future for high performance polymers in structural applications, electrical industries, electronic and electrooptical industries, membrane technologies, fuel cell membranes and other fields such as conductive polymers. 4. Concluding remarks.