Synthesis of high molecular

There are two commercial PPS processes being practiced worldwide the Phillips process and the Kureha process. Although these processes contain some common steps, there are distinguishing features, most notably in the reagents used to faciUtate the synthesis of high molecular weight linear PPS. 

The first polyimine was reported by Adams and coworkers [182] from terephthalaldehyde and benzidine and dianisidine. Between 1950 and 1959 Marval and coworkers [174-176] reported a number of polyimines. Suematsu and coworkers [170] reported the first successful synthesis of high molecular weight fully aromatic polyimines by solution polycondensation method using w-cresol as reaction medium. 

Wayland et al. reported the use of tetramesitylporphyrin complexes (CoTMP), including 118231 and 119251 in the synthesis of high molecular weight PMA with very low dispersities (1.1-1.3). Arvanilopoulos et al.m have reported similar chemistry with alkylcobaloximes (120) as photoinitiators at low temperatures. 

Synthesis of High Molecular Weight Poly (p-Pinene)... 

Linear step-growth polymerizations require exceptionally pure monomers in order to ensure 1 1 stoichiometry for mutually reactive functional groups. For example, the synthesis of high-molecular-weight polyamides requires a 1 1 molar ratio of a dicarboxylic acid and a diamine. In many commercial processes, the polymerization process is designed to ensure perfect functional group stoichiometry. For example, commercial polyesterification processes often utilize dimethyl terephthalate (DMT) in the presence of excess ethylene glycol (EG) to form the stoichiometric precursor bis(hydroxyethyl)terephthalate (BHET) in situ. 

The SnAt reactions were first successfully used in the synthesis of high-molecular-weight poly(arylene etherjs by Johnson et al.4,5 This reaction represents a good example for poly(ether sulfonejs in general, either in laboratory -or industrial-scale preparations. In this procedure, the bisphenol A and sodium hydroxide with an exact mole ratio of 1 2 were dissolved into dimethyl sulfoxide (DMSO)-chlorobenzene. The bisphenol A was converted into disodium bisphenolate A, and water was removed by azeotropic distillation. After the formation of the anhydrous disodium bisphenolate A, an equal molar amount of 4,4,-dichlorodiphenyl sulfone (DCDPS) was added in chlorobenzene under anhydrous conditions and the temperature was increased to 160°C for over 1 h... 

Scheme 6.15 Synthesis of high-molecular-weight PEEK via /-butyl containing a soluble PEK precursor.

Characteristic initiation behavior of rare earth metals was also found in the polymerization of polar and nonpolar monomers. In spite of the accelarated development of living isotactic [15] and syndiotactic [16] polymerizations of methyl methacrylate (MMA), the lowest polydispersity indices obtained remain in the region of Mw/Mn = 1.08 for an Mn of only 21 200. Thus, the synthesis of high molecular weight polymers (Mn > 100 x 103) with Mw/Mn < 1.05 is still an important target in both polar and nonpolar polymer chemistry. Undoubtedly, the availability of compositionally pure materials is a must for the accurate physical and chemical characterization of polymeric materials. 

K. Nomura, H. Morimoto, Y. Imanishi, Z. Ramhani, and Y. Geerts, Synthesis of high molecular weight rra i-poly(9,9-di- -octylfluorene-2,7-vinylene) by the acyclic diene metathesis polymerization using molybdenum catalysts, J. Polym. Sci., Part A Polym. Chem., 39 2463-2470, 2001. 

In the late 1970s, Kirchhoff at Dow Chemical Company developed the use of benzocyclobutenes in polymer synthesis and modification. These efforts culminated in 1985 with the issuance of the first patent describing the use of benzocyclobutene in the synthesis of high-molecular-weight polymer.27 Similar work that involved a thermosetting system based on Diels-Alder cycloaddition between terminal benzocyclobutene and alkyne groups,28,29 was reported separately and independently by Tan and Arnold.28 Since these initial discoveries, the field of benzocyclobutene polymers has expanded rapidly and benzocyclobutene chemistry constitutes the basis of a new and versatile approach to the synthesis of high-performance polymers for applications in the electronics and aerospace industries.30... 

Gertrude Walsh Robinson developed a new method for the synthesis of high-molecular-weight fatty acids, and she was active in penicillin research during the Second World War. Baker writes (1954) "It is perhaps not generally known that she was the first chemist to prepare synthetical material with genuine antibiotic character of the penicillin type" (567). 

Phase-transfer techniques are widely used for the preparation of polymers. For example, potassium fluoride is used to produce poly(etherketone)s under phase-transfer conditions (Scheme 10.18). Use of this reagent allows the chloroaro-matics to be used as starting material as opposed to the more expensive flu-oroaromatics that are usually employed [23]. This method is suitable for the synthesis of high molecular weight semicrystalline poly(ether ketone)s, although the presence of excess potassium fluoride in the reaction mixture can lead to degradation reactions. The use of a phase transfer catalyst can allow the use of water-soluble radical initiators, such as potassium peroxomonosulfate used to promote the free-radical polymerization of acrylonitrile [24],... 

Above all, the discovery that some organometallic compounds are effective in the synthesis of high molecular weight PCL [7] promoted a renewed interest in the ROP of lactones, particularly with alkyl metals, metal halides, oxides, car-boxylates, and alkoxides. These metal compounds were first classified as anionic... 

Lou X, Detrembleur C, Jerome R (2002) Living cationic polymerization of 5-valerolactone and synthesis of high molecular weight homopolymer and asymmetric telechelic and block copolymer. Macromolecules 35 1190-1195... 

Yoneda, S., Kawamoto, H., and Nakatsubo, F., Synthesis of high molecular mass condensed tannins by cationic polymerization of flavan-3,4-carbonate, J. Chem. Soc., Perkin Trans. 1, 1025, 1997. 

Fig. 19. The polymerization flask designed for the synthesis of high-molecular-weighi (Mn>500,000) poly(methyl methacrylates) by the high-speed living polymerization with the (porphyrinato)aluminium enolate (2)-Lewis acid (3e) systems...

Research Focus Synthesis of high-molecular-weight biphenylpolyheterocyclics useful as... 

Miihlradt, P.R Synthesis of high molecular weight polyphosphate with a partially purified enzyme from Salmonella. J. Gen. Microbiol., 68, 115-122 (1971)... 

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