Polyimides from isomeric oxydiphthalic anhydrides

Abstract

Abstract2,2′,3,3′‐Oxydiphthalic dianhydride (2,2′,3,3′‐ODPA) and 2,3,3′,4′‐ODPA were synthesized from 3‐chlorophthalic anhydride with 2,3‐xylenol and 3,4‐xylenol, respectively. Their structures were determined via single‐crystal X‐ray diffraction. A series of polyimides derived from isomeric ODPAs with several diamines were prepared in dimethylacetamide (DMAc) with the conventional two‐step method. Matrix‐assisted laser desorption/ionization time‐of‐flight spectra showed that the polymerization of 2,2′,3,3′‐ODPA with 4,4′‐oxydianiline (ODA) has a greater trend to form cyclic oligomers than that of 2,3,3′,4′‐ODPA. Both 2,2′,3,3′‐ODPA and 2,3,3′,4′‐ODPA based polyimides have good solubility in polar aprotic solvents such as DMAc, dimethylformamide, and N‐methylpyrrolidone. The 5% weight‐loss temperatures of all polyimides were obtained near 500 °C in air. Their glass‐transition temperatures measured by dynamic mechanical thermal analysis or differential scanning calorimetry decreased according to the order of polyimides on the basis of 2,2′,3,3′‐ODPA, 2,3,3′,4′‐ODPA, and 3,3′,4,4′‐ODPA. The wide‐angle X‐ray diffraction of all polyimide films from isomeric ODPAs and ODA showed some certain extent of crystallization after stretching. Rheological properties revealed that polyimide (2,3,3′,4′‐ODPA/ODA) has a comparatively lower melt viscosity than its isomers, which indicated its better melt processability. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3249–3260, 2003

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

“…It was reasoned that introduction of the monomers containing asymmetric or noncoplanar structure to replace the linear symmetrical dianhydride in polymer chain could weaken the interchain interaction thus enhancing the solubility and melt flowability [6]. As of result of that, it has been further demonstrated that replacement of the symmetrical dianhydride in PIs with asymmetric ones decreases the melt viscosity but increases the T g relative to the corresponding symmetrical PIs [4,[7][8][9]. Thioetherdiphthalic anhydride (TDPA) is an aromatic bridged dianhydride which has three isomers as shown in Figure 1.…”

“…According to the research on a similar dianhydride ODPA, TDPA-based polyimides show similar thermal stability and mechanical properties as ODPA-based polyimides, meanwhile, more excellent melt flowability. Moreover, the synthesis of TDPA is more convenient than that of ODPA [4]. Copolymerization by incorporating monomers with flexible moieties, which disrupts the regularity of molecular chain and prevents the interaction of polymer chains, is a simple but effective way for structure modification to balance the processability and the desired properties [14,15].…”

“…However, these advantages, meanwhile, give rise to poor solubility and processability of PIs. General methods to improve the processability are to incorporate flexible linkage into the polymer backbones [2][3][4]. This approach, nevertheless, inevitably leads to a decrease of glass transition temperature (T g ) in many cases.…”

Synthesis and characterization of high performance poly(thioether imide)s via aromatic nucleophilic substitution reaction of isomeric AB-type monomers

“…What is more, the copolyimides PTIs (b-d) had slightly better solubility than the homopolyimides PTIs (a, e) in m-cresol and phenol. That was because unsymmetrical 3-and 4-substituted phthalimide unit disturbed the regularity of molecular chain, which reduced the intermolecular interaction and hindered molecular chain close stacking and, therefore, improved the solubility of isomeric PTIs [20][21][22][23][24][25][26].…”

“…Recently, our group has successfully synthesized series of isomeric polythioetherimides by the polycondensation of isomeric dianhydrides and diamines [18][19][20][21] or by aromatic nucleophilic substitution reactions of isomeric bis(chlorophthalimide)s with bisthiophenols [22][23][24][25]. Isomeric polyimides, which possess geometrically asymmetric and noncoplanar moieties, were found to be endowed with improved solubility, low melt viscosity, comparable thermal and mechanical properties [26].…”