Ketenes copolymerisation

The coordination polymerisation of heterounsaturated monomers, such as aldehydes [101-103] and ketones [104], isocyanates [105] and ketenes [106,107], in homopolymerisation systems has not been widely described in the literature. However, the coordination copolymerisation of heterounsaturated monomers not susceptible to homopropagation, such as carbon dioxide [71,108-113], with heterounsaturated monomers such as cyclic ethers has been successfully carried out and is of increasing interest. 

Heterounsaturated monomers that undergo coordination polymerisation or copolymerisation with other monomers can be divided into two classes monomers with a carbene-like structure such as isocyanides and carbon monoxide which are coordinated by n complex formation with the transition metal atom at the catalyst active site, and monomers such as isocyanates, aldehydes, ketones and ketenes which are coordinated via 5-bond formation with the metal atom at the catalyst active site. 

The copolymerisation of ketene and acetaldehyde was carried out with ethyl-zinc diphenylamide as the catalyst. It was found to yield an alternating copolymer [scheme (43)], the respective polyester of highly isotactic structure (Table 9.3) [279] ... 

A new route to a controlled synthesis of heavily aromatic substituted polyesters has been investigated. The method involves an alternating copolymerisation of an aldehyde and a ketene. PEK and MBA can be copolymerised under /THF/nBuLi/ — 20°C/LiCl/CH3OH/ conditions to obtain an alternating PEK/ MBA copolymer MJM = 1.15, = 5.1 kg/mol). The alternating structure... 

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