Methacrylates, activated reactivity ratios

Labelled monomers have been used in co-polymerizations for analysis of the resulting co-polymers and consequent determination of monomer reactivity ratios (15, 16). This technique is of particular value when the compositions of the different monomer units are rather similar or when the co-polymer contains only very small amounts of one of the monomers. These points can be appreciated by considering calculations on co-polymers of methyl methacrylate and methyl acrylate summarized in Table 1. The analyses have been calculated ignoring contributions of end-groups it assumed that the acrylate ester is labelled with carbon-14 and that specific activities are expressed in units such as curies/g of carbon. 

Novel iron carbonyl monomer, r)4-(2,4-hexadien-l-yl acrylate)tricarbonyl-iron, 23, was prepared and both homopolymerized and copolymerized with acrylonitrile, vinyl acetate, styrene, and methyl methacrylate using AIBN initiation in benzene.70,71 72 The reactivity ratios obtained demonstrated that 23 was a more active acrylate than ferrocenylmethyl acrylate, 2. The thermal decomposition of the soluble homopolymer in air at 200°C led to the formation of Fe203 particles within a cross-linked matrix. This monomer raised the glass transition temperatures of the copolymers.70 The T)4-(diene)tricarbonyliron functions of 23 in styrene copolymers were converted in high yields to TT-allyltetracarbonyliron cations in the presence of HBF4 and CO.71 Exposure to nucleophiles gave 1,4-addition products of the diene group.71... 

Reactivity ratios of a number of activated acrylates and methacrylates with different structural monomers are given in Table 2. Polymer compositions produced at low conversions from equimolar monomer fe compositions are also indicated in the Table. These values are back calculated from the reactivity ratios, and are hence equivalent to experimental data. The actual copolymeriz-ability patterns of three comonomer pairs are also shown in Fig. 4. These results show that, among the various monomer pairs, AOTcp with styrene, and AOTcp with 7V-vinylpyrrolidone, produce azotropic copolymers at about equimolar monomer feed compositions. The relatively small reactivity ratios of these two monomer pairs indicate that their equimolar copolymerization produces approximately alternating, rather than random or block, copolymers. 

Macromonomeres, styrenic, of polyoxyethylene 52 Maleic derivatives 49 Mechanical stability 47 Mesogens, disc-like 216 Methacrylates, activated 3 -, -, reactivity ratios 7 Methacrylic polymerizable end groups 52 Methyl free radicals 88 Micelle concentration, critical 47, 48, 55 Mono-radicals 91-103... 

Reactivity ratios exhibit a weak temperature dependence that is often difficult to measure. With increasing temperature, the ratios tend to approach unity as demonstrated for styrene-butyl acrylate [28], butyl acrylate-methyl methacrylate [29], and ethylene copolymer systems [30, 31]. The temperature dependencies of the latter values agree well with activation energies reported for addition of monomers to small radicals [32]. 

Haddleton, D. M., et al. (1997). Identifying the nature of the active species in the polymerization of methacrylates inhibition of methyl methacrylate homopolymerizations and reactivity ratios for copolymerization of methyl methacrylate/n-butyl methacrylate in classical anionic, alkyUithium/trialkylaluminum-initiated, group transfer polymerization, atom transfer radical polymerization, catalytic chain transfer, and classical free radical polymerization. Macromolecules, 30(14) 3992-3998. 

Most of the reported polyfvinyl ether) macromonomers have been prepared with a methacrylate end group which can be radically polymerized and which is non-reactive under cationic polymerization conditions [71-73]. Generally, the synthesis was based on the use of the functional initiator 30, which contains a methacrylate ester group and a function able to initiate the cationic polymerization of vinyl ethers. Such initiator can be obtained by the reaction of HI and the corresponding vinyl ether. With initiator 30 the polymerization of ethyl vinyl ether (EVE) was performed using I2 as an activator in toluene at -40 °C. The MW increased in direct proportion with conversion, and narrow MWD (Mw/Mn= 1.05-1.15) was obtained. The chain length could be controlled by the monomer to initiator feed ratio. Three poly(EVE) macromonomers of different length were prepared by this method Mn=1200,5400, and 9700 g mol-1. After complete... 

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