Synthesis and Thermal Properties of Polythioetherimides Derived from 4,4'-[p-Thiobis(phenylenesulfanyl)]Diphthalic Anhydride and Various Aromatic Diamines

Abstract

An asymmetrical aromatic diamine, 1-(4'-aminophenoxy)-4-(4'-aminophenylenesulfanyl) benzene (OSDA) was synthesized. A series of polythioetherimides (PTEIs) were prepared from a thioether-bridged aromatic dianhydride 4,4'-[ p-thiobis(phenylenesulfanyl)]diphthalic anhydride (3SDEA) and various aromatic diamines having ether or thioether linkages between phenylene rings by a two-step polycondensation procedure via their soluble poly(amic acid) (PAA) precursors. Medium to high molecular weight PAAs were obtained with inherent viscosities near or higher than 1.0 dL g-1, which is high enough to afford flexible and tough PTEI films except for PI-2 (3SDEA-134APB) and PI-6 (3SDEA- m2SPDA) derived from meta-ether-substituted diamines. PI-2 and PI-6 showed some extent of crystallinity compared to the amorphous natures of the other polymers. The PTEI films exhibit good resistance to organic solvents except for PI-3 (3SDEA-133APB), which is soluble in N-methyl-2-pyrrolidinone (NMP) and sulfuric acid at room temperature. The PTEI films show good thermal stability with the 5% weight loss temperatures being above 480°C both in nitrogen and in air. The glass transition temperatures of the PTEIs are in the range of 155—191°C, which are lower than those of the commercial polyetherimides due to their plural thioether linkages in the main chains.

Melt processable homo- and copolyimides with high thermo-oxidative stability as derived from mixed thioetherdiphthalic anhydride isomers

“…It is worthwhile to note that the T 5% of these copolyimides in air is higher than that in nitrogen which is just contrary to a majority of PIs. This phenomenon has been found in the other sulfur-containing polymers, which is ascribed to the different degradation mechanisms in various atmospheres [12,22].…”

“…As a consequence, thioether links have been introduced to many polymers. And polythioetherimides have been synthesized by many researchers for different purposes [10][11][12]. In previous research, PIs based on 2,3,3',4'-thioetherdiphthalic anhydride (3,4'-TDPA) exhibited a higher T g than that of symmetric 3,3',4,4'-thioetherdiphthalic anhydride (4,4'-TDPA) and also presented a remarkable drop in the complex viscosity above T g [13].…”

Phenylethynyl-terminated imide oligomers derived from thioetherdiphthalic anhydride isomers with decreased melt viscosities

“…This phenomenon was ascribed to the different degradation mechanisms in various atmospheres, which had been found in the other sulfur-containing polymers. 27,30,37 The first stage was the reaction process of sulfur and air and the second stage was the decomposition of the backbone of PIs.…”

Preparation, characterization, and properties of poly(thioether imide)s from isomeric bis(chlorophthalimide)s and bisthiophenols

“…The possible decomposition was that sulfur was oxidized to sulfoxide or sulfone in air. [39][40][41] All those T 5% values in air and under nitrogen atmospheres demonstrated that the isomeric PTIs possess moderate thermal and thermal oxidative stability. Furthermore, the thermal oxidative resistance of polymers can also be testified by the char yields, which were over 55% at 800 C under nitrogen atmosphere.…”