Ethylene oxide copolymerisation

By copolymerising with a small amount of second monomer which acts as an obstruction to the unzipping reaction, in the event of this being allowed to start. On the industrial scale methyl methacrylate is sometimes copolymerised with a small amount of ethyl acrylate, and formaldehyde copolymerised with ethylene oxide or 1,3-dioxolane for this very reason. 

The coordination polymerisation and copolymerisation of heterocyclic monomers have been restricted in industry to a much smaller volume than the polymerisation and copolymerisation of hydrocarbon monomers polyether elastomers from epichlorohydrin and ethylene oxide or propylene oxide, and allyl glycidyl ether as the vulcanisable monomeric unit, are produced on a larger scale [4-7],... 

Oxirane/cyclic acid anhydride alternating copolymers of controlled molecular weight with a narrow molecular weight distribution were found by Aida et al. [188,189] to be formed under mild conditions when copolymerising ethylene oxide and phthalic anhydride in the presence of the (tpp)AlCl-quater-nary phosphonium salt catalyst system. The copolymerisation carried out with (tpp)AlCl alone proceeded very slowly, and the product was not polyethylene terephthalate) but contained ether linkages in considerable amount. The development of the living character and the tendency towards alternation of the copolymerisation when using the aluminium porphyrin catalyst, coupled with a quaternary salt, have been postulated [188,189] to be due to the formation of... 

The copolymerisation of ethylene oxide and phenyl isocyanate has been found [266] to proceed in the presence of the triethylaluminium-water (2 1) catalyst, although phenyl isocyanate alone could not be polymerised by the same catalyst. The copolymer formed was characterised by an alternating comonomer distribution [scheme (39)] and contained acetalic units in its chains (Table 9.4) ... 

Commercial products are complex mixtures of partial fatty acid esters of sorbitol and its mono- and dianhydrides copolymerised with approximately 20 moles (usually) of ethylene oxide for each mole of sorbitol and... 

Ishida and co-workers [14] applied reactive pyrolysis of copolymer polyacetals in the presence of cobalt sulfate incorporated into Py-GC equipped with a high-resolution capillary separation column. The method was successfully applied to study the sequence distributions in polyacetals containing low levels of copolymerised ethylene oxide units. The E contents and the distributions of E sequences up to E in polymers were evaluated on the basis of peak intensities of cyclic ethers containing E units on the pyrogram. 

Chromium Oxide-Based Catalysts. Chromium oxide-based catalysts were originally developed by Phillips Petroleum Company for the manufacture of HDPE resins subsequendy, they have been modified for ethylene—a-olefin copolymerisation reactions (10). These catalysts use a mixed sihca—titania support containing from 2 to 20 wt % of Ti. After the deposition of chromium species onto the support, the catalyst is first oxidised by an oxygen—air mixture and then reduced at increased temperatures with carbon monoxide. The catalyst systems used for ethylene copolymerisation consist of sohd catalysts and co-catalysts, ie, triaLkylboron or trialkyl aluminum compounds. Ethylene—a-olefin copolymers produced with these catalysts have very broad molecular weight distributions, characterised by M.Jin the 12—35 and MER in the 80—200 range. 

M-NHC catalysts in this area. Metal catalysed carbonylation also provides an alternative synthetic ronte to the prodnction of materials that traditionally reqnire highly toxic precnrsors, like phosgene. This section discnsses carbonylation of aryl hahdes, oxidative carbonylation of phenolic and amino componnds, carbonylation of aryl diazoninm ions, alcohol carbonylation, carbonylative amidation, and copolymerisation of ethylene and CO. 

Heck-type step-growth condensation polymerisation involves mainly palladium-based catalysts, although nickel-based catalysts are also effective. It is worth noting that this polycondensation requires a change in the oxidation state of the metal (e.g. Pd) [schemes (30) and (31)] [71], which is in contrast to chain growth polymerisation, such as ethylene/carbon monoxide alternating copolymerisation promoted by Pd-based catalysts [schemes (82) and (83) in Chapter 3], for which the preservation of the oxidation state of palladium, Pd(II), is typical [83-85] ... 

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