Régis Mercier

Gas transport mechanism in sulfonated polyimides. Consequences on gas selectivity

Abstract Structure–properties relationships in terms of gas transport have been established for a large series of sulfonated copolyimides synthesized with a naphthalenic dianhydride, a sulfonated diamine [SD] and various non-sulfonated diamines. For these two phases systems, a phase inversion has been evidenced for sulfonated block content ranging between 30 and 50%. The contribution of the dispersed sulfonated phase to the gas transport greatly depends on the structure of the non-sulfonated diamine. As a consequence, a large range of permeability values can be obtained varying the nature of the non-sulfonated diamine, the sulfonated diamine content and the sulfonated block length. The diffusion coefficient is in all cases the dominant factor in the transport phenomena and good compromise between O 2 /N 2 selectivity and O 2 flux can be achieved with these systems.

Water vapour transport mechanism in naphthalenic sulfonated polyimides

Abstract The morphology and the water transport properties of a large series of sulfonated copolyimides synthesised with a naphthalenic dianhydride, a sulfonated diamine and various non-sulfonated diamines were studied. For a sulfonated diamine content in the total diamine amount higher than 30%, the copolymers are composed by a continuous ionic phase and a dispersed non-sulfonated phase. The water sorption isotherms are of BET type II for all the copolymers and they result from the contribution of both the sulfonated and non-sulfonated phases. For the sulfonated phase, a two step sorption mechanism has been identified. It consists at low activity in sorption on ionic sites but also in unrelaxed holes formed during the triethylammonium/H + ionic exchange and at high activity in a clustering process. The contribution of the non-sulfonated phase to the transport phenomenon can be modulated by the hindrance brought by the non-sulfonated diamine and by its more or less hydrophobic character.

Synthesis of 2,4,5-triarylimidazoles in aqueous solution, under microwave irradiation

A series of 2,4,5-triarylimidazoles was synthesized from a new, highly efficient and green method. The reaction is performed in water, without the presence of any catalyst, and under microwave irradiation. This provides new opportunities for the rapid screening of a wide range of compounds, either for the development of new drugs, or original compounds for the material scientist.

Copolyimides with trifluoromethyl or methoxy substituents. NMR characterization

Abstract In the first stage, a series of aromatic diamine compounds such as 2-methoxy-5,4′-diaminodiphenyl ether (ODAOMe) and 2-trifluomethyl-4,4′-diaminodiphenyl ether (ODACF 3 ) were synthesized. These aromatic diamines and 4,4′-diaminodiphenyl ether (ODA) were then used to prepare copolyimides with 4,4′-oxydiphthalic anhydride (ODPA) and bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA). Both chemical composition and the arrangements of repetitive units were characterized by 1 H and 19 F NMR. It was shown that solubility and thermal stability are related to the BCDA fraction in the copolymers and to the chemical structure of the diamine.

Assisted Microwave Synthesis of High Molecular Weight Poly(ArylEtherKetone)s

A microwave-assisted aromatic nucleophilic substitution reaction has been used to synthesize high molecular weight Poly(ArylEtherKetone)s (PAEKs) within very short reaction times and through a highly simplified process. The influence of different parameters, (namely the microwave power, solvent nature, or reaction time) on the polymer molecular weights were studied in order to optimize the polymerization conditions. The polymers thus obtained were characterized and compared with their analogues synthesized by conventional thermal polycondensation. This work underlines the potential of microwave-assisted aromatic polymer synthesis.

Water-borne Polyimides via Microwave-assisted Polymerization

In the present study, the synthesis of high molecular weight polyimides was conducted in water using microwave irradiation. High molecular weight polymers were obtained after only 5 min of reaction time. The influence of different experimental parameters is discussed in connection with a thorough characterization of the synthesized polymers. From these polymers, self-supporting films were obtained.

Mechanistic Aspects of Polynaphthalimide Synthesis from NMR Analysis

The mechanism of the polycondensation reaction leading to naphthalimide polymers has been investigated using a model compound. In complement to 19F-NMR analysis, 1H- and 13C-NMR spectroscopies were used to identify the intermediate compound. It was concluded that there was no evidence for the formation of an isoimide, but the formation of an amide—acid intermediate was clearly demonstrated.