Addition polymerisation epoxides

Ca.ta.lysts, A small amount of quinoline promotes the formation of rigid foams (qv) from diols and unsaturated dicarboxyhc acids (100). Acrolein and methacrolein 1,4-addition polymerisation is catalysed by lithium complexes of quinoline (101). Organic bases, including quinoline, promote the dehydrogenation of unbranched alkanes to unbranched alkenes using platinum on sodium mordenite (102). The peracetic acid epoxidation of a wide range of alkenes is catalysed by 8-hydroxyquinoline (103). Hydroformylation catalysts have been improved using 2-quinolone [59-31-4] (104) (see Catalysis). 

Epoxide/aliphatic amine or polyamide blends Air drying Addition polymerisation Blends rich in higher ketones Fairly good Very good Poor Very good Fairly good/ good Finishes need to be supplied in two separate containers and mixed just prior to use... 

The most important commercial polymers prepared by this method are obtained from monomers containing a carbon-carbon double bond. In such cases the reaction is called vinyl polymerisation. The addition polymerisation is also important for carbonyl compounds and 1, 2-epoxides. 

Poly(epoxides) are readily prepared by a ring-opening addition polymerisation catalysed by anionic, cationic or coordination catalysts. Consider the polymerisation of an epoxide bearing a single substituent ... 

Epoxide/amino or phenolic resin blends Stoving Addition and condensation polymerisation Blends rich in higher ketones and alcohols Good Good Very good Very good Good ... 

Simvastatin, a conjugated alkene, can polymerise as a result of peroxyl radical addition. The peroxide-linked oligomers can be subsequently cleaved to produce epoxides, which in turn degrade to form ketones and alcohols [69]. Inclusion of vitamin E (a-tocopherol) into formulations was found to inhibit chain-oxidation of simvastatin, lovastatin and other structurally related statins. 

Carbocation-oxonium ion equilibria are obvious complicating factors in studies of the kinetics of initiation of polymerisation and useful thermodynamic data for such equilibria involving Ph3C+ and a variety of linear and cyclic ethers have been reported by Slomkowski and Penczek (132). A dramatic increase in rates of initiation of polymerisation of THF induced by Ph3C+ salts is observed on addition of small amounts of epoxides such as propylene oxide (113a,b), which compete favourably with THF in the primary carbocation-oxonium ion equilibria and simplify the initiation reaction ... 

These compounds can initiate anionic polymerisation of epoxides, and when R, = H the secondary amine can react by addition to an epoxide group. Farkas and Strohm 64> have studied the reaction of 2-ethyl-4-methyl imidazole with phenyl glycidyl ether and BADGE resin using chemical analysis and proton NMR spectroscopy. They found that the imidazole readily forms adducts with epoxide of 1 1 and 1 2 molecular ratio ... 

In practice the epoxide-amine cure is often accelerated by the addition of catalysts such as boron trifluoride complexes, and the boron trifluoride-ethylamine adduct (BFE) is widely used for this purpose. In addition to catalysing the epoxide-amine reactions, BFE can initiate homopolymerisation of epoxide. The accelerating effect of BFE is illustrated by DSC scans for the TGDDM/DDS/BFE system in Figure 12. The multiple-peaked exotherm associated with the BFE-catalysed TGDDM/DDS cure indicates that the kinetics of this system are more complex than those for the cure with amine alone. For this system the overall heat of reaction was found to decrease with increasing BFE concentration 89). For DDS alone Q0 was about 110 kJ per mole epoxide while the value for BFE alone was 75 kJ/mole, and the DDS/BFE values were between these limits. It appears that the proportion of epoxide homo-polymerisation relative to amine or hydroxyl addition increases with increasing BFE concentration. 

The first report on the coordination polymerisation of epoxide, leading to a stereoregular (isotactic) polymer, concerned the polymerisation of propylene oxide in the presence of a ferric chloride-propylene oxide catalyst the respective patent appeared in 1955 [13]. In this catalyst, which is referred to as the Pruitt Baggett adduct of the general formula Cl(C3H60)vFe(Cl)(0C3H6),CI, two substituents of the alcoholate type formed by the addition of propylene oxide to Fe Cl bonds and one chlorine atom at the iron atom are present [14]. A few years later, various types of catalyst effective for stereoselective polymerisation of propylene oxide were found and developed aluminium isopropoxide-zinc chloride [15], dialkylzinc-water [16], dialkylzinc alcohol [16], trialkylalumi-nium water [17] and trialkylaluminium-water acetylacetone [18] and trialkyla-luminium lanthanide triacetylacetonate H20 [19]. Other important catalysts for the stereoselective polymerisation of propylene oxide, such as bimetallic /1-oxoalkoxides of the [(R0)2A10]2Zn type, were obtained by condensation of zinc acetate with aluminium isopropoxide in a 1 2 molar ratio of reactants [20-22]. 

The reaction between epoxides and HF gives fluorohydrins and, generally, other products resulting from extensive polymerisation. However, the acidity and reactivity of HF may be decreased by the addition of a base, either an amine or KF, or by complexation with a Lewis acid, such as borontrifluoride etherate [174]. Consequently, pyridine-HF, Et3N-3HF [203] and -Pr2NH-3HF [204] efficiently cleave epoxides to give excellent yields of fluorohydrins (Figure 3.39). 

After workup with ammonium chloride (liberation of NH3 and NaCl) and extraction with hot dimethylsulfoxide products 4 and 5 can be isolated as white solids in yields of ca. 30 %. The low yield of the desired product observed for the epoxide addition reaction is attributed to an anionic epoxide polymerisation process [5],... 

Latex with hydroxyl functionalised cores of a methyl methacrylate/butyl acrylate/2-hydroxyethyl methacrylate copolymer, and carboxyl functionalised shells of a methyl methacrylate/butyl acrylate/methacrylic acid copolymer was prepared by free radical polymerisation. The latex was crosslinked using a cycloaliphatic diepoxide added by three alternative modes with the monomers during synthesis dissolved in the solvent and added after latex preparation and emulsified separately, then added. The latex film properties, including viscoelasticity, hardness, tensile properties, and water adsorption were evaluated as functions of crosslinker addition mode. Latex morphology was studied by transmission electron and atomic force microscopy. Optimum results were achieved by introducing half the epoxide by two-step emulsion polymerisation, the balance being added to the latex either in solution or as an emulsion. 8 refs. 

Offering for example enhanced heat and chemical resistance over even the best tetraphthalic polyester, there is close chemical relationship between the other two and the bisphenol-A starting point, a condensation product of phenol with acetone under acidic conditions. Then come those epoxides which, as a product of a further reaction between bisphenol and epichlorohydrin, are applicable to composites. In turn the vinyl esters can be considered as an epoxy resin backbone with terminal acrylic ester groups, dissolved in or diluted by -similar to unsaturated polyester - a monomer like styrene, which can itself be polymerised. All are chemically cured or promoted, with or without the addition of heat, although the epoxides are more selective to the use of amines for this purpose, than the other two where the peroxides are the more common. 

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