▪ Abstract High-temperature polymers have found widespread use in aerospace and electronics applications. This review deals with recent developments in the chemistry of these materials that have led to improvements in processability and high-temperature stability.

Recent advances in the development of processable high-temperature polymers1

A new adamantane-based dietheramine, 2,2-bis[4-(4-aminophenoxy)phenyl]adamantane, was prepared in two steps from chloro displacement or p-chloronitrobenzene with the potassium phenolate of 2,2-bis(4-hydroxyphenyl)adamantane, followed by hydrazine catalytic reduction of the intermediate dinitro compound. A series of polyimides with the adamantane-2,2-diyl unit as a cardo group was prepared from the adamantane-based dietheramine and various aromatic dianhydrides by a conventional two-stage synthesis in which the poly(amic acid)s obtained in the first stage were heated stage-by-stage at 150-270 °C to give the polyimides. The intermediate poly(amic acid)s had inherent viscosities between 0.82 and 1.66 dL/g. Except for the polyimide from pyromellitic dianhydride, all of the polyimides could be dissolved in NMP, and several polyimides also showed good solubility in other organic solvents. All of the polyimides were amorphous in nature as evidenced by X-ray diffractograms. The glass-transition temperatures (Tg) of these polyimides were recorded between 248 and 308 °C by differential scanning calorimetry (DSC), and the softening temperatures (T s ) determined by thermomechanical analysis (TMA) stayed in the range of 254-335 °C. Decomposition temperatures for 10% weight loss all occurred above 500 °C in both air and nitrogen atmospheres.

Synthesis and characterization of new adamantane-based polyimides

The novel spirobifluorene diamine monomer, 2,7-bis-amino-2‘,7‘-di-tert-butyl-9,9‘-spirobifluorene, was obtained. The new organosoluble polyimides were prepared from spirobifluorene diamine containing bulky tert-butyl group and conventional dianhydrides as well as 2,2‘-bis(4‘ ‘-tert-butylphenyl)-4,4‘,5,5‘-biphenyltetracarboxylic dianhydride (BBBPAn) and 2,2‘-bis(4‘ ‘-trimethylsilylphenyl)-4,4‘,5,5‘-biphenyltetracarboxylic dianhydride (BTSBPAn), which are composed of a noncoplanar twisted biphenyl unit containing bulky p-tert-butylphenyl groups and/or p-trimethylsilylphenyl groups by high-temperature one step polymerization. The structures of polymers were confirmed by various spectroscopic techniques. The weight-average molecular weights and polydispersities of resulting polymers were in the ranges 48 300−183 900 and 2.10−3.26, respectively. The bulky and twisted noncoplanar structural feature confers an enhanced solubility of the polyimides because of a decrease in the degree of molecular packing and crys...

Synthesis and Characterization of Highly Soluble and Oxygen Permeable New Polyimides Based on Twisted Biphenyl Dianhydride and Spirobifluorene Diamine

Synthesis and properties of fluorinated polyimides. 3. Derived from novel 1,3-bis[3′-trifluoromethyl-4′(4″-amino benzoxy) benzyl] benzene and 4,4-bis[3′-trifluoromethyl-4′(4-amino benzoxy) benzyl] biphenyl

Polyimides comprising high polarized moieties and electron-withdrawing groups usually exhibit high refractive index and good transparency with great potential for optoelectronic devices. Particularly, the incorporation of hydroxyl groups on the backbones of polyimides is an important strategy to enhance the solubility and provide reactive sites for organic-inorganic bonding. Composites prepared from organic polymer binder and inorganic fillers have recently attracted considerable interests due to their enhanced mechanical, thermal, optical and electrical properties compared to the corresponding polymer or inorganic component. Moreover, the inorganic components in hybrid films can also serve as electron acceptors for stabilizing the charge transfer complex thus result in electrically programmable digital memory properties. In addition, the high performance polyimides can further served as substrate and protector for the AgNWs-polyimide conductive hybrid films, exhibiting good adhesive property, high bendability, and excellent thermal stability. Owing to the high glass transition temperature ( T g ) of polyimides, the resulted AgNWs-polyimide electrode can maintain its conducting performance at high temperature operation. Thus, the hybrid electrode provided extremely high potential to operate at harsh working environment or further post processing. By the excellent combination of transparent polyimides and inorganic materials, the resulting polyimide hybrids showing promising potential are indispensable to optical and electrical applications.

Highly transparent polyimide hybrids for optoelectronic applications

Having previously demonstrated the possibility of synthesizing high molecular weight poly(ether imide)s with ortho-linked main-chain units from bis(ether anhydride)s derived from catechol or its derivatives, we now provide a preliminary assessment of the properties of the polymers prepared from the catechol bis(ether anhydride) and a variety of diamines. The polymers have low color, are soluble in a variety of solvents, and are thermally stable to temperatures in excess of 470 °C. Glass transition temperatures are comparable with or higher than that of the commercial poly(ether imide) Ultem. Solvent-cast films have high modului and strengths. Extensions to break are relatively low, except for the polymer based on 4,4‘-bis(4-aminophenoxy)biphenyl, which has an extension of 170%. All the polymers can be drawn to produce materials with higher moduli and strengths and, in most cases, higher extensions to break. Thus the polymers can be processed from the melt or from solution.

G. C. Eastmond

Papers

Melt-Processable Poly(ether imide)s Based on Catechol Bis(ether anhydride)