Ring-opening polymerization polyether synthesis

Poly(tetramethylene oxide) polyols (see Scheme 4.4) are a special class of polyethers syndiesized via acid-catalyzed ring-opening polymerization of tetrahy-drofuran. Although less susceptible to side reactions, the synthesis of these C4 ethers is less flexible in terms of product composition and structure. Thus, because of diis syndietic route, only two-functional glycols are available and copolymers are not readily available. Molecular weights of commercial C4 glycols range up to about 3000 g/m. 

Scheme 4.12 Conventional synthesis of polyether polyols via base-catalyzed ring-opening polymerization of alkylene oxides.

Lewis acid-assisted high-speed living anionic polymerization can be applied not only to the accelerated synthesis of naiTOw MWD poly(methacrylic esters) but also to the synthesis of polyethers from epoxides (11) and polyesters from lactones (14 and 15) with aluminum porphyrins as initiators. Furthermore, ring-opening polymerization of episulfides (18) with zinc AT-substituted porphyrins (5) can also be accelerated by Lewis acids. 

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

In parallel, NHCs were also used as initiators for the ring-opening polymerization of epoxides. This could be executed for the synthesis of polyethers of ethylene oxides. The living zwitterionic intermediate could further react with 8-caprolactone to generate di-block co-polymers in one pot. ... 

Magnusson H, Malmstrom E, Hult A (1999) Synthesis of hyptabranched aliphatic polyethers via cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane. Macromol Rapid Commun 20 453 57... 

The synthesis of well-defined polyethers by ROP has only been reported for a limited number of monomers that have enougji ring-strain to be readily opened, namely ethylene oxide, oxetane and THF. Moreover, the rather similar reactivity of the cyclic ether bonds and the ring-opened polymeric ether bonds in combination... 

Maynard HD, Grubbs RH (1999) Synthesis of functionalized polyethers by ring-opening metathesis polymerization of unsaturated crown ethers. Macromolecules 32 6917-6924... 

Block copolymer systems have aroused interest with reviews of the synthesis of nylon elastomers, thermoplastic polyether-polyamide elastomers, and thermoplastic cross-linked polyamides of 3,3 -bis(hydroxymelhyl) glutaric add. Block copolymers were also reported from poly(/n-phenylene isophthalamidc) and poly(ethylene oxide) or poly(dimethylsiloxane). The polycondensation of oco -dicarboxylic-poly(amide 11) and x -dihydroxy-polyoxyethylene has also been studied and rate constants and activation energies evaluated for the process. The polycondensation of axo -diacid and e9o> -diester-poly(amide 11) oligomers with cuco -dihydroxy-polyether oligomers has similarly been reported. Lactam Rli -opening Polymerization Routes.—The effects of ring size, substitution and the presence of heteroatoms on the polymerizability of lactams has been the subject of reviews. - In the field of lactam polymerization, two systems have evoked major interest, namely caprolactam and 2-pyrrolidone. Studies on caprolactam have reported the effect of water on the mechanism of polymerization and polymerization rate, where it was found that the process was... 

Scheme 8 Synthesis of hyperbranched polyethers via cationic ring-opening multibranching polymerization of EHO.

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