Poly , aromatic

Aliphatic—aromatic poly(amide—imides) based on N,1S7-bis(carboxyalkyl)-benzophenone-3,3, 4,4 -tetracarboxyhc diimides have shown a 10% weight loss at 400°C (14). 

Neuse, E. Aromatic Poly benzimidazoles. Syntheses, Properties, and Applications. Vol. 47, pp. 1—42. 

S. Janietz and S. Anlauf, A new class of organosoluble rigid-rod fully aromatic poly(l,3,4-oxadia-zolejs and their solid-state properties, 1., Macromol. Chem. Phys., 203 427-432, 2002. 

As depicted in Scheme 2, homopolymerization of 1 to form the aromatic poly(aryl ether) 6FNE utilized the Scholl reaction in nitrobenzene with anhydrous ferric chloride at room temperature. A 100-ml round-bottom flask was charged... 

Aromatic poly(aryl ether ketone)s containing 1,4-naphthalene moieties were prepared by the reaction of a bisphenol and 2 in the presence of potassium carbonate in DM Ac at 160°C as depicted in Scheme 3. A typical polymerization was carried out as follows To a 100-ml round-bottom flask was added 8.32 g (O.OlOmol) of2, 3.36g (O.OlOmol) of4,4 -(hexafluoroisopropylidene) diphenol, 51.2 g ofDMAc, and 3.1 g (0.022 mol) of potassium carbonate. The mixture was heated to 160°C with stirring under nitrogen for 18 h. The mixture was allowed to cool to room temperature. The polymer was precipitated by pouring the reaction mixture into a blender containing about 100 ml of water, filtered, washed three times with water and dried to yield 8.1 g (92% yield) as a white powder. 

Hexafluoroisopropylidene-unit-containing aromatic poly(ether ketone)s were first synthesized from an alkaline metal salt of Bisphenol AF (1) and 4,4 -difluoro-benzophenone.14 Cassidy and co-workers prepared hexafluoroisopropylidene-unit-containing poly(ether ketone)s by condensing 2,2-bis[4-(4-fluorobenzoyl)-phenyl]-l,l,l,3,3,3-hexafluoropropane (9) and 2,2-bis[4-(4-fluorobenzoyl)-phenyljpropane (10) with Bisphenol AF (1) or Bisphenol A (4) (Scheme 7).15 The reactions are nucleophilic aromatic displacements and were conducted in DMAc at 155- 160°C with an excess of anhydrous potassium carbonate. After 3 to 6 h of reaction, high-molecular-weight poly(ketone)s are obtained in high yields. 

A powerful and efficient method for the preparation of poly(ketone)s is the direct polycondensation of dicarboxylic acids with aromatic compounds or of aromatic carboxylic acids using phosphorus pentoxide/methanesulfonic acid (PPMA)16 or polyphosphoric acid (PPA)17 as the condensing agent and solvent. By applying both of these reagents to the synthesis of hexafluoroisopropylidene-unit-containing aromatic poly(ketone)s, various types of poly(ketone)s such as poly(ether ketone) (11), poly(ketone) (12), poly(sulfide ketone) (13), and poly-... 

Novel fluorine-containing aromatic poly(azomethine)s are prepared by the reaction of hexafluoroisopropylidene-unit-containing aromatic diamines, 2,2-bis[4-(4-aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane (17) and 2,2-bis(4-aminophenyl)-l, 1,1,3,3,3-hexafluoropropane (18) with terephthalaldehyde (19) or isophthalaldehyde (20)20 (Scheme 11). 

Wholly aromatic poly(azomethine)s possess remarkable thermal stability, and high strength and modulus. However, owing to their limited solubility and infusibility, it is difficult to obtain poly(azomethine)s having sufficiently high molecular weight and useful processability. 

The incorporation of fluorine atoms improves the solubility of aromatic condensation polymers without causing them to lose their high thermal stability and modifies the processability. Hexafluoroisopropylidene-unit-containing poly-(azomethine)s and copoly(azomethine)s are readily soluble in highly polar solvents such as DMAc, HMPA, and NMP, and they also dissolve completely in dichloromethane, chloroform, and THF, whereas poly(azomethine)s derived from 21 and 22 and having no fluorine atom are insoluble in these solvents.20 Accordingly, the solubility of aromatic poly(azomethine)s is remarkably improved by substituting isopropylidene units with fluorine atoms. 

Several routes have been reported for the synthesis of aromatic poly(azole)s such as poly(benzimidazole), poly(benzoaxazole), and poly(benzthiazole) melt polycondensation of dicarboxylic acid diphenyl esters with tetramines21 and high-temperature solution polycondensation of dicarboxylic acids or their derivatives with tetramine hydrochlorides in PPA.22 PPA acts as condensing agent and solvent. Ueda etal.23 developed a modified method for the synthesis ofpolyazoles with the use of PPM A. 

Fluorine-containing aromatic poly(benzimidazole)s are synthesized by direct polycondensation of 2,2-bis(4-carboxyphenyl)-l, 1,1,3,3,3-hexafluoropropane (15) with 3,3 -diaminobenzidine tetrahydrochloride (23) (Scheme 13) and 1,2,4,5-benzenetetramine tetrahydrochloride (24) (Scheme 14) in PMMA or PPA.24... 

High-molecular-weight fluorine-containing aromatic poly(benzoxazole)s have not been obtained either by the direct solution polycondensation in PPA at 200°C or by the low-temperature solution polycondensation in DMAc at 0 to 5°C from 2,2-bis(3-amino-4-hydroxyphenyl)-l,l,l,3,3,3-hexafluoropropane and aromatic diacid derivatives because the fluorine-containing monomer has low nucleophilicity owing to the presence of the electron-withdrawing hexafluoroiso-propylidene unit. 

High-molecular-weight aromatic poly(benzothiazole)s can be obtained from dichloride (26) of 15 and 29 in PPA under similar reaction conditions (Scheme 17). 

Aromatic poly(benzoxazole)s exhibit excellent thermal stability. Rigid-rod poly(benzoxazole)s are fabricated into high-strength and high-modulus fibers. Fluorine-containing aromatic poly(benzoxarole)s are expected to have unique properties. 

Aromatic poly(benzothiazole)s are thermally and thermooxidatively stable and have outstanding chemical resistance and third-order nonlinear optical susceptibility. Aromatic poly(benzothiazole)s can be spun into highly-oriented ultrahigh strength and ultrahigh modulus fibers. However, this type of polymer is insoluble in most organic solvents. Therefore, hexafluoroisopropylidene units are introduced in the polymer backbone to obtain soluble or processable aromatic poly(benzothiazole)s. 

The aromatic poly(benzothiazole) from 15 and 29 is almost amorphous and easily soluble in strong acids such as concentrated sulfuric acid and methane-sulfonic acid.26 It also dissolves in organic solvents such as HMPA and o-chlorophenol. The increased solubility and amorphous nature of this polymer is also ascribed to reduced intermolecular forces and to looser packing owing to the presence of highly distorted diphenylhexafluoroisopropylidene units in the polymer backbone. 

Transparent, flexible, and tough films with deep orange color are cast from HMPA solution of poly(benzothiazole) from 15 and 29.26 The tensile strength of 69Mpa and the tensile modulus of 2.7 GPa are obtained for aromatic poly(ben-zoxazole) (28) from 15 and 29. These values are higher than those of hexafluoroisopropylidene-unit-containing poly(benzimidazole). 

Aroma isolation, 11 516-521 distillations for, 11 519 solvent extraction for, 11 518 Aroma perception, taste and, 11 522-523 Aroma therapy, 18 354 Aromatic-(poly)cycloaliphatic diphenols, interfacial condensation of, 23 723-724... 

Aromatic nitrations, 17 160-161 by-products of, 17 161 kinetics of, 17 162 Aromatic nitriles, 17 243 Aromatic nucleophilic displacement, polyimide synthesis via, 20 273 Aromatic phosphines, 19 60, 62 Aromatic poly(monosulfide ketone)s, 23 709 Aromatic poly(monosulfide)s, 23 706 Aromatic polyamide copolymers, laboratory synthesis of, 19 720 Aromatic polyamide fibers, 24 614 Aromatic polyamides, 10 210-212 19 713-738. See also Aliphatic polyamides (PA)... 

Interfacial condensation, 23 730 of aromatic-(poly)cycloaliphatic diphenols, 23 723-724 polysulfonate preparation by,... 

Radiation-Resistant, Amorphous, All-Aromatic Poly (ary lene ether sulfones)... 

Miller et al. [87,88] have described the synthesis of hyperbranched aromatic poly(ether-ketone)s based on monomers containing one phenolic group and two fluorides which were activated towards nucleophilic substitution by neighboring groups. The molecular weight and polydispersity of the formed po-ly(ether-ketone)s could be controlled by reaction conditions such as monomer concentration and temperature. The formed polymers had high solubility in common solvents such as THF. 

An example for the synthesis of poly(2,6-dimethyl-l,4-phenylene oxide) - aromatic poly(ether-sulfone) - poly(2,6-dimethyl-1,4-pheny-lene oxide) ABA triblock copolymer is presented in Scheme 6. Quantitative etherification of the two polymer chain ends has been accomplished under mild reaction conditions detailed elsewhere(11). Figure 4 presents the 200 MHz Ir-NMR spectra of the co-(2,6-dimethyl-phenol) poly(2,6-dimethyl-l,4-phenylene oxide), of the 01, w-di(chloroally) aromatic polyether sulfone and of the obtained ABA triblock copolymers as convincing evidence for the quantitative reaction of the parent pol3rmers chain ends. Additional evidence for the very clean synthetic procedure comes from the gel permeation chromatograms of the two starting oligomers and of the obtained ABA triblock copolymer presented in Figure 5. 

---