Polyimides containing

Polyimides containing C—F bonds have been receiving strong attention (96—98). Fluorine-containing polyimides possess lower dielectric constant and dielectric loss because of reduced water absorption and lower electronic polarization of C—F bonds vs the corresponding C—H bonds. Fluorine-containing polyimides are often more soluble and readily processible without sacrificing thermal stabilities. The materials are appHed primarily iu... 

Resins for advanced composites can be classified according to their chemistry typical resins are polyaryletherketones, polysulfides, polysulfones, and a very broad class of polyimides containing one or more additional functional groups (Table 2) (see also Engineering plastics). 

Semicrystalline Polyimides. Semicrystalline polyimides containing carbonyl and ether groups have been synthesized by the group at the NASA Langley Research Center (37). One such material, designated LARC-CPI, which is an acronym for Langley Research Center—Crystalline Polyimide,... 

Important for both the synthesis and modification of polymers is also the elongation of polymer chains. Bisnitrile oxides have been claimed as reagents for chain elongation of polyimides containing terminal groups with C=C, C=C, C=N, C=0, and C=N bonds (504). 

Miyatake, K., Asano, N. and Watanabe, M. 2003. Synthesis and properties of novel sulfonated polyimides containing 1,5-naphthylene moieties. Journal of Polymer Science Part A Polymer Chemistry 41 3901-3907. 

Figure 24. Synthesis of a five-membered ring sulfonated polyimide containing phosphine oxide.

Polyetherimides (PEI) are polyimides containing sufficient ether as well as other flexibi-lizing structural units to impart melt processability by conventional techniques, such as injection molding and extrusion. The commercially available PEI (trade name Ultem) is the polymer synthesized by nucleophilic aromatic substitution between 1,3-bis(4-nitrophthalimido) benzene and the disodium salt of bisphenol A (Eq. 2-209) [Clagett, 1986]. This is the same reaction as that used to synthesize polyethersulfones and polyetherketones (Eq. 2-206) except that nitrite ion is displaced instead of halide. Polymerization is carried out at 80-130°C in a polar solvent (NMP, DMAC). It is also possible to synthesize the same polymer by using the diamine-dianhydride reaction. Everything being equal (cost and availability of pure reactants), the nucleophilic substitution reaction is probably the preferred route due to the more moderate reaction conditions. 

The recently reported value of q = 13 nm for a soluble aromatic polyimide containing entirely 77-catenations - exemplifies the differences that symmetry makes in terms of the persistence length. We did not obtain the persistence... 

Shirai et al. [71] also synthesized a novel class of polyimides containing M(II) phthalocyanine rings by solution condensation in iV-Me-2-pyrrolidone of M(II) [2,9, or 10,2,16 or 17-bis(3,4-dicarboxy benzoyl)] phthalocyanine dianhydride with 2,6-diaminopyridine followed by thermal imidation [71] (Fig. 23). 

An alternative order of introducing acylating reagents onto the bis[3-amino-4-(p-aminophenoxy)]-benzophenone, that is, the addition of first bis(phthalic anhydride) and then phthalic anhydride to the tetramine, yields polyimides containing predominantly N-phthalimide o-substituents (Scheme 3.7). These polyimides are characterised by higher viscosities and softening temperatures (Table 3.8) but poorer solubilities as compared to those polymerised according to Scheme 3.6. 

Introduction of the hinge groups may cause a greater effect on polymer solubility polyimides containing hexyloxy side groups demonstrate much better solubility than methoxy-substituted polyimides [8]. 

Among the polyimides containing aromatic substituents, the most well-known systems are phenoxy-substituted polymers. Syntheses of phenoxy-substituted polyimides are carried out [22-27] in accordance with Scheme 5.3. Syntheses of the polyimides were carried out using three different methods [27] ... 

Polymers obtained using 3,5-diaminodiphenyl ether may be considered as m-phenylenediamine-based polyimides containing phenoxy side groups. A comparison of these two polymer group properties has demonstrated that introduction of phenoxy substituents leads to an increase of polymer solubility and decrease of Tg indicating that phenoxy side groups behave as chemical plasticisers this conclusion is an agreement with the literature [5, 27-31]. 

In addition to the polyimides containing five-membered imide rings (polyphthalimides), polyimides containing six-membered naphthylimide cycles (polynaphthylimides and polyperyleneimides) have been synthesised. These polymers are known to be more stable - hydrolytically and thermally - than polyphthalimides [32-36]. 

Polyimides containing phenylsnlfide and phenylsnlfone side groups [40, 41] were obtained in accordance with Scheme 5.5. General properties of the polyimides obtained are listed in Table 5.7. 

Synthesis of polyimides containing benzothiazole-2-sulfide groups was carried out using high-temperature polycyclocondensation in w-cresol in accordance with Scheme 5.7 [41, 44]. All the polyimide synthesis reactions were homogeneous and yielded polymers having reduced viscosities Pred = 0.29-0.42 dl/g, Tg = 215-265 °C and 10% weight loss temperature = 325-400 °C (Table 5.9). 

Polyimides containing N-phthalimido and methyl side groups were prepared by the interaction of... 

Polyimides Containing Aliphatic and Other Flexible Spacers. .. 26... 

Table 4. Monomers for polyimides containing more than one flexible linkage ... 

Structural modifications to attain soluble aromatic polyimides have also been carried out by introducing bulky substituents, aryl or heterocyclic rings. One of the first references to this approach was made by Korschak and Rusanov, who synthesized soluble aromatic polyimides containing side phthalimide groups [85 ]. More recent work by Rusanov et al. has enriched this topic with new soluble polyimides containing pendent imide groups [86,87]. 

Fully imidized soluble polyimides have ben prepared using monomers derived from diphenylindane and aromatic dianhydrides. Technical polymers (XU218, for instance), prepared from 1,1,3-trimethyl-diaminophenylindane and benzophenone-tetracarboxylic acid dianhydride, have been marketed over the last decade. Despite the partially aliphatic nature of polyimides containing the indane group, they show considerable retention of the thermal stability, with Tg values over 300 °C [107-110]. 

Efforts continue in the Far East, particularly in Japan, by Horie et al., on photosensitive polyimides containing epoxide groups [44,45]. These studies focus on the chemical amplification of photo crosslinks in the resulting materials for use in making mask materials in silicon chip fabrication. 

Polyimides containing polyaromatic amines, (I) and (II), were previously prepared by the author [1] and used as electronic insulating agents. 

Thermal dimerization of perfluoroalkcnes is also a good approach for obtaining interesting dimeric fluoro-substituted compounds. A -[4-Phenoxy-3-(trifluorovinyl)phenyl]phthalimide (3), which is a model for polyimides containing trifluorovinyl groups, undergoes thermal dimerization at 140-160"C to give predominantly the trtf .s-1,2,3,3,4,4-hexafluoro-l,2-bis(2-phenoxy-5-phthalimidophenyl)cyclobutane (4).6 See Section 2.1.1.6.2. for a more detailed discussion of this [2 + 2]-cycloaddition process. 

Tanihara N, Tanaka K, Kita H, and Okamoto K. Pervaporation of organic liquid mixtures through membranes of polyimides containing methyl-substituted phenylenediamine moieties. J Membr Sci 1994 95 161-169. 

Sillion et al [47] prepared polyimides containing benzhydrol groups by using the reduction product of benzophenonetetracarboxylic acid dimethyl ester shown below. 

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