Polyethers synthesis

Fluorinated polyethers, synthesis of, 363 Fluorinated polymers, 361-363 Fluorine effect, 361 Fluorine-ended PEEK, 360 Foams... 

Gokel, G. W. and Korzenowski, S. H. (1982). MacrocycUc Polyether Synthesis, vol. 13 in Reactivity and Structure Concepts in Organic Chemistry. Springer-Verlag, Berlin... 

Gokel, G.W. Korzeniowski, S.H. "Macrocyclic Polyether Synthesis," Springer-Verlag, New York, New York, 1982. 

Ford, L. A., DesMarteau, D. D. and Smith, D. W., Jr. 2005. Perfluorocyclobutyl (PFCB) aromatic polyethers Synthesis and characterization of new sulfonamide containing monomers and fluoropolymers. Journal of Fluorine Chemistry 126 653-660. 

G. W. Gokel and S. H. Korzeniowski, Macrocyclic Polyether Synthesis , Springer-Verlag, Heidelberg, 1982. 

Gokel, G.W. Korzeniovski, S.H. Macrocyclic Polyether Synthesis. Verlag Chemie Berlin, 1982. 

There are various procedures for the preparation of polyethers. These procedures typically start with oxirane or oxirane derivatives (e.g. propylene oxide, etc.). Base catalyzed anionic polymerization, acid initiation, or complex coordination catalysis can be used for the reaction [1-3], Not only oxiranes can generate polyethers. Diols also can be used for polyether synthesis. Other source compounds include tetrahydrofuran, which can be polymerized to a polyether using fluorosulfonic acid (HSO3F) as a catalyst, oxetane (trimethylene oxide) or oxetane derivatives, which can be polymerized to generate polyethers with practical applications such as poly[bis(chloromethyl)oxetane], etc. 

Stepanova A. R. Liguid-crystalline polyethers synthesis on the basis of biphenyl derivatives. // Abstract of Chemistry Masters. Thesis. St. Peterburg 1992. 

In the history of PU, some continuous processes for polyether polyol synthesis by anionic polymerisation were developed, but only at small scale (i.e., pilot plant). Tubular reactors with static mixing systems or a column with plate reactor types were used, but these technologies were not extended to industrial scale levels. The first continuous process for high MW polyether synthesis was developed by Bayer (IMPACT Technology) and is based on the very rapid coordinative polymerisation of alkylene oxides, especially PO, with dimetallic catalysts (DMC catalysts - see Chapter 5). A principle technological scheme of a polyether polyol fabrication plant is presented in Figure 4.30. 

Figure 4.30 Scheme for polyether polyol fabrication by anionic polymerisation of alkylene oxides, initiated by glycerol or diols (variant). 1 - Reactor for potassium glycerolate synthesis 2 - Reactor for prepolyether synthesis 3 - Reactor for polyether synthesis 4 - Reactor for purification 5 - Filter press 6 - Storage tank for final purified poly ether 7 - Heat exchangers for removal of the reaction heat 8 - Condensers 9 - Vacuum pumps 10 - Vessels for distilled water 11 - Recirculation pumps 12 - Gear pump or screw (or double screw) pump... 

In conclusion, to obtain a good, resilient, flexible PU foam without collapse, with high rise and free of blow holes, it is necessary that the PO used for the polyether synthesis be free of high MW PPO contaminants. 

The propionaldehyde content of PO strongly affects the colour of the resulting polyether polyols, explained by an uncontrolled condensation of the aldehyde in the presence of an alkaline medium. A maximum of 10 ppm of propionaldehyde in PO of is perfect for a very good colour in the resulting polyether polyols. A maximum content of 50 ppm propionaldehyde is acceptable, but the crude polyether has a yellow colour, which fortunately is removed in the propoxylation step. A propionaldehyde level higher than 100 ppm leads to serious colour problems in polyether synthesis. 

Xylitol (Figure 17.2), a polyol starter for rigid polyether synthesis, having five hydroxyl groups, is produced by the hydrogenation of the same pentosans used for THF synthesis [8]. By propoxylation of xylitol excellent rigid polyether polyols (see Chapter 4.1) are obtained. 

Gokel, G. W. Korzeniowski, S. H. Macrocyclic Polyether Synthesis Springer Verlag Berlin 1982. 

A priori, there are two possibilities for synthesising the polyarylene sulphones. Either a polyether synthesis could be used to join up the aryl sulphone intermediates with ether linkages or a polysulphonylation process employed to link up aryl ethers. In practice either method can be used and will give polymers of hi molecular wei t provided that the intermediates are selected tfithin certain structuiml limitations and the reactim conditions are closdy controlled. The methods are quite different chemically and a polymer structiire made by one route cannot usually be made by the other, althou some structures can be made by either process. 

N. Karak, B. Roy and B. Voit, s-Triazine based hyperbranched polyethers Synthesis, characterization and properties , J Polym Sci Part A Polym Chem, 2010, 68,3994-4004. 

Polyether synthesis From activated or metal-free anionic ring-opening polymerization of epoxides to functionahzation 13PPS845. 

M. Jayakannan, S. Ramakrishnan, Recent developments in polyether synthesis, Mac-romol. Rapid Commun. 22 (18) (2001) 1463-1473. 

D.W. Smith Jr., D.A. Babb, Perfluorocy-clobutane aromatic polyethers. Synthesis and characterization of new siloxane-containing fluoropolymers. Macromolecules 29 (3) (1996) 852-860. 

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