Preparation and Properties of Novel Aromatic Polyimides from 4,4′-Diamino-4″ -Hydroxytriphenylamine and Aromatic Tetracarboxylic Dianhydrides

Abstract

Novel aromatic polyimides containing hydroxytriphenylamine units were prepared from 4,4′-diamino-4″-hydroxytriphenylamine 1 and various aromatic tetracarboxylic dianhydrides 2. The glass transition temperatures ( Tgs) of these polyimides were in the range of 274–388 °C and the 10% weight loss temperatures ( T d10s) were above 462 and 511 °C in air and nitrogen respectively. Polyimide 4f prepared from diamine 1 and 4,4′-hexafluoroisopropylidenebis(phthalic anhydride) (6FDA) was soluble not only in organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 1, 3-dimethyl-2-imidazolidone and dimethyl sulfoxide but also in tetramethylammonium hydroxide aqueous solution. Other resulting polyimides were not soluble in organic solvents. The resulting polyimides 4 possessed Tgs about 20–70 °C higher and poorer solubilities than the previously reported polyimides prepared from 4,4′-diaminotriphenylamine and various aromatic tetracarboxylic dianhydrides. These results indicated that polymer properties such as thermal behaviour and solubilities were influenced by the intermolecular interaction of hydrogen bonding due to hydroxy units.

New fluorene‐based thermally stable five‐ and six‐membered rings polyimides with enhanced solubility

“…As it was mentioned, one of the main drawbacks of polyimides is their low solubility. For instance, it has been reported that most of polyimides derived from 4,4′‐diamino‐4″‐hydroxytriphenylamine monomer were not soluble in organic solvents 24. The reported solubility of polyimides derived form 2,6‐bis(3‐ aminobenzoyl) pyridine was about 1 g/dL 25…”

“…On the other hands, the solubility of polyimides derived from BTDA and 6FDA was higher than PMDA, NTDA, and PTDA‐derived polyimides. Presence of some flexible groups was the main reason for this behavior because of the fact that carbonyl and hexaflouroisopropylidene groups in BTDA and 6FDA respectively, have low rotational bond energy in comparison to the other polyimides, which reduced the polymer chains interaction and rigidity 15, 24, 30…”

Synthesis and Characterization of Pyridine-Based Polyurethanes

“…Polymers containing Schiff base units in the main chain display many special properties, such as excellent mechanical strength, high thermal stability, semiconducting, good optoelectronic properties and thermotropic liquid crystalline behavior [5,6]. Hard segmented PUs show poor solubility in common organic solvents due to their rigid backbones [7,8], which limits their application and makes it difficult to process them.…”

Synthesis and characterization of novel polyurethanes based on N1,N4‐bis[(4‐hydroxyphenyl)methylene]succinohydrazide hard segment

“…Many PUs and polyureas were found to be insoluble in common organic solvents due to their rigid backbones,9, 10 thereby inhibiting their applications due to difficulty in their processing. To overcome such difficulties, polymer structure modification is necessary, wherein one can introduce asymmetric or bulky groups on the pendant polymer backbone or incorporate noncoplanar structural units on the main polymer chain 11–14. In our previous papers,15–17 Schiff‐based PUs, chalcone‐based PUs and azo‐based diol containing PUs have been prepared using 2,2′‐{ethane‐1,2‐diylbis(nitrilomethylylidene)}diphenol, 2,2′‐{hexane‐1,6‐diylbis(nitrilomethylylidene)} diphenol, 2,2′‐{1,4‐phenylenebis‐[nitrilomethylylidene]}diphenol, 2,2′‐{4,4′‐methylene di‐2‐methylphenylene‐1,1′‐bis[nitrilomethylylidene]}diphenol, 2,6‐bis(4‐hydroxy‐benzylidene)cyclohexanone, 4,4′‐[1,4‐phenylenedi‐diazene‐2,1‐diyl]bis(2‐carboxy‐phenol), and 4,4′‐[1,4‐phenylenedi‐diazene‐2,1‐diyl]bis(2‐chlorophenol) with different diisocyanates.…”