Ring-opening polymerization synthesis

Cheng, M. AttygaUe, A. B. Lohkovsky, E. B. Coates, G W. Single-site catalysts for ring-opening polymerization Synthesis of heterotactic poly(lactic acid) from roc-lactide. J. Am. Chem. Soc. 1999, 121, 11583-11584. 

Synthesis. The synthesis of poly(dichlotophosphazene) [25034-79-17, (N=PCl2) (4), the patent polymer to over 300 macromolecules of types (1) and (2), is carried out via controlled, ring-opening polymerization of the corresponding cycHc trimer, (N=PCl2)3 [940-71 -6]. 

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.

Ring-opening polymerization has played an important role in systematic approaches to the chemical synthesis of polysaccharides and the clarification of their biomedically interesting characteristics in relation to their own molecular structures. The early... 

Recently, Cohn and Salomon synthesized and characterized a series of PLCL thermoplastic bioelastomers by two-step synthesis procedure. First, ring-opening polymerization of L-lactide initiated by the hydroxyl terminal groups of the PCL chain. Second, chain extension polymerization of these PLA-PCL-PLA triblocks initiated by the hexamethylene diisocyanate (HDl). 

As early as 1895, the synthesis of polydichlorophosphazene was attempted by H.N. Stokes by thermal ring-opening polymerization of hexachloro-triphosphazene [(NPCl2)3]. The product obtained by H.N. Stokes was a high-molecular weight cross-linked rubbery material called inorganic rubber which is insoluble in all solvents and hydrolytically decomposes into phosphates, ammonia, and hydrochloric acid in the presence of moisture. Because of its insolubility and hydrolytic instability, the polymer found no technological application and remained as a laboratory curiosity. 

In 1964, H.R. Allcock filed a patent claiming the preparation of a soluble polydichlorophosphazene. The polymer obtained can be soluble in organic solvents such as benzene and toluene. This thermal ring-opening polymerization of hexachloro-triphosphazene in the melt at 250°C is the most fully developed and commonly used method for polydichlorophosphazene synthesis to date. 

Xiao CS, Zhao CW, He P, Tang ZH, Chen XS, Jing XB (2010) Facile synthesis of glycopo-lypeptides by combination of ring-opening polymerization of an alkyne-substituted N-carboxyanhydride and click glycosylation . Macromol Rapid Commun 31 991-997... 

In polyester synthesis via ring-opening polymerizations, metal catalysts are often used. For medical applications of polyesters, however, there has been concern about harmful effects of the metallic residues. Enzymatic synthesis of a metal-free polyester was demonstrated by the polymerization of l,4-dioxan-2-one using Candida antarctica lipase (lipase CA). Under appropriate reaction conditions, the high molecular weight polymer (molecular weight = 4.1 x 10" ) was obtained. 

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