Styrene a-methylstyrene

Such copolymers of oxygen have been prepared from styrene, a-methylstyrene, indene, ketenes, butadiene, isoprene, l,l-diphen5iethylene, methyl methacrjiate, methyl acrylate, acrylonitrile, and vinyl chloride (44,66,109). 1,3-Dienes, such as butadiene, yield randomly distributed 1,2- and 1,4-copolymers. Oxygen pressure and olefin stmcture are important factors in these reactions for example, other products, eg, carbonyl compounds, epoxides, etc, can form at low oxygen pressures. Polymers possessing dialkyl peroxide moieties in the polymer backbone have also been prepared by base-catalyzed condensations of di(hydroxy-/ f2 -alkyl) peroxides with dibasic acid chlorides or bis(chloroformates) (110). 

Several alkenes are converted to aziridines by treating with oxaziridine (52) at elevated temperatures. Styrene, a-methylstyrene and their derivatives substituted in the benzene ring react smoothly, and so do 1,1-diphenylethylene, indene and acrylonitrile (74KGS1629). 

Polymers of a-methylstyrene have been marketed for various purposes but have not become of importance for mouldings and extrusions. On the other hand copolymers containing a-methylstyrene are currently marketed. Styrene-a -methylstyrene polymers are transparent, water-white materials with BS softening points of 104-106°C (c.f. 100°C for normal polystyrenes). These materials have melt viscosities slightly higher than that of heat-resistant polystyrene homopolymer. 

Applications As the basic process of electron transfer at an electrode is a fundamental electrochemical principle, polarography can widely be applied. Polarography can be used to determine electroreductible substances such as monomers, organic peroxides, accelerators and antioxidants in solvent extracts of polymers. Residual amounts of monomers remain in manufactured batches of (co)polymers. For food-packaging applications, it is necessary to ensure that the content of such monomers is below regulated level. Polarography has been used for a variety of monomers (styrene, a-methylstyrene, acrylic acid, acrylamide, acrylonitrile, methylmethacrylate) in... 

A heterogeneous Pd catalyst dispersed on supports such as o-A1203, C, MgO and CaC03 was found to be an recyclable and selective catalyst for heterogeneous Heck arylation (an important method of C-C bond formation - Chapt. 11) of several olefins (styrene, a-methylstyrene, 1-decene, acrylonitrile, etc.) with iodobenzene [45], Scheme 10.5. 

Typical monomers which polymerise through cationic mechanisms are isobutene, styrene, a-methylstyrene, vinyl ethers and vinyl carbazoles. At present, about 100 vinyl monomers are known that can be polymerised by the cationic initiators. 

Ever since 1962, when Williams, Okamura, and their associates started to publish propagation rate-constants k+p for the cationic bulk polymerization of cyclo-pentadiene, isobutene, styrene, a-methylstyrene and isopropylvinyl ether by ionizing radiations, these constants have been accepted as the best, most likely, values for the k+p of unpaired cations in a medium of low-polarity, and those obtained subsequently by Stannett and his collaborators, using similar methods, enjoyed the same status, (The loci classici are Bates et al. (1962), Bonin et al. (1964), Taylor Williams (1969) and the three papers by Ueno et al. (1967), Hayashi et al. (1967) and Williams et al. (1967).)... 

After Williams initial reports (Bonin etal., 1965 Hubman etal., 1966), the most detailed account of the methods used for determining kp+ is in the group of three papers resulting from the cooperation of Williams with Okamura s group in Kyoto (Ueno et al., 1967 Hayashi et al., 1967 Williams et al., 1967) in these the kp+ of styrene, a-methylstyrene and isobutyl vinyl ether were reported. The bulk polymerisation of styrene and of a-methylstyrene gave kp+ values of the same order of magnitude (ca. 106) and two orders of magnitude less than those for cyclopentadiene and isobutene the same is true for our kpi shown in Table 1. 

Olefin styrene, a-methylstyrene, frans-p-methylstyrene, 1-hexene, c/s and frans-4-octene, c-pentene, c-hexene, c-heptene, indene, 1,2-dihydronaphthalene... 

Hydrocarbon resins comprise a range of low-molecular-weight products (M < 3000) used as adhesives, hot-melt coatings, tackifying agents, inks, and additives in rubber. These include products based on monomers derived from petroleum as well as plant sources. The petroleum-derived products include polymers produced from various alkenes, isoprene, piperylene, styrene, a-methylstyrene, vinyltuolene, and dicyclopentadiene. The plant-derived products include polyterpenes obtained by the polymerization of dipentene, limonene,... 

Among the most extensive studies of monomer reactivity have been those involving the copolymerization of various meta- and para-substituted styrenes with other styrene monomers (styrene, a-methylstyrene, and p-chlorostyrene) as the reference monomer [Kennedy and Marechal, 1983], The relative reactivities of the various substituted styrenes have been correlated by the Hammett sigma-rho relationship ... 

The general characteristics of anionic copolymerization are very similar to those of cationic copolymerization. There is a tendency toward ideal behavior in most anionic copolymerizations. Steric effects give rise to an alternating tendency for certain comonomer pairs. Thus the styrene-p-methylstyrene pair shows ideal behavior with t = 5.3, fy = 0.18, r fy = 0.95, while the styrene-a-methylstyrene pair shows a tendency toward alternation with t — 35, r% = 0.003, i ii 2 — 0.11 [Bhattacharyya et al., 1963 Shima et al., 1962]. The steric effect of the additional substituent in the a-position hinders the addition of a-methylstyrene to a-methylstyrene anion. The tendency toward alternation is essentially complete in the copolymerizations of the sterically hindered monomers 1,1-diphenylethylene and trans-, 2-diphe-nylethylene with 1,3-butadiene, isoprene, and 2,3-dimethyl-l,3-butadiene [Yuki et al., 1964]. 

Rh(C2H4)2CI]2 Phosphinated acetal of cross-linked styrene a-Methylstyrene 2-Ethyl-1-hexene 28... 

Recent laser flash photolysis (LFP) studies have provided absolute rates of addition of perfluoro-n-alkyl radicals to a variety of alkenes in solution [ 114,115]. In these studies, C2Fj, C3F7, and n-C7F,5 were generated instantaneously by photolysis of the respective diacyl peroxides. The initially-formed perfluoroacyloxyl radicals decarboxylated rapidly to yield the perfluoroalkyl radicals, after which the additions of these radicals to styrene, a-methylstyrene, etc. were monitored directly via observation of the growth of UV absorption due to the transient benzylic radicals. 

Conjugated dehydrogenation of isopropylbenzene was planned [87] by the method of experiments with the minimal number of tests. Total yields of styrene and a-methylstyrene per injected isopropylbenzene were taken for optimized parameters, because these monomers are equally valuable. At the gradient motion (T = 640 °C) the highest yield of the target products (styrene + a-methylstyrene) equaled 56.8% with about 90% selectivity. Further gradient motion was of no practical interest due to a process selectivity decrease down to 80%. 

Olefins ethylene, styrene, a-methylstyrene, divinylbenzene, and vinyltoluene. 

The study by low-angle X-ray diffraction and electron microscopy of concentrated solutions of the copolymers in preferential solvents for polybutadiene (iso-prene, butadiene) or for poly(a-methyl styrene) (styrene, a-methylstyrene, methyl methacrylate, methylethyl ketone) and of copolymers in the dry state obtained by slow evaporation of the solvent from the mesophases have shown the existence of three types of structure hexagonal, lamellar, and inverse hexagonal depending upon the copolymer composition84,85. The factors governing the structural type and the structural parameters are the same as in the case of polystyrene-polybutadiene copolymers85. ... 

The comparison of copolymers SB, BMS and BVN with the same compositions and molecular weight and exhibiting all a lamellar structure has shown that the extension of the macromolecular chains depends upon the nature of the nonpolybutadiene blocks. The extension of the chains increases in the order styrene, a-methylstyrene, vinylnaphtalene and the extension of the polybutadiene chain is caused by that of the adjoined chain85. ... 

When vinyl monomers such as isobutene, styrene, a-methylstyrene, and vinyl ethers are irradiated by ionizing radiation, the polymerizations of these mono-... 

The dimerization of the anion radicals was studied in NAH/THF and LAH/THF by following the decay of the absorption maxima of the styrene, a-methylstyrene, and 1,1-diphenylethylene radical-anions. The dimerization followed second order kinetics with the rate constants shown in Table 2. The absorption spectrum with a peak at 320 nm, which grew concomitantly with the decay of the ion-pair MST, Na+(or Li+) was assigned to the dimeric dianion MSMS in the form of the solvent-separated ion pair (Fig. 5). 

Electrical Conductivity. Hayashi et al. (14) have made electrical conductivity measurements in irradiated styrene, a-methylstyrene, and isobutyl vinyl ether. The observed specific conductivities in these monomers were of the same order of magnitude, at a given dose rate, as that measured in cyclohexane. Since the G values for ion production in most hydrocarbon liquids are approximately the same, they concluded that the conducting species in the monomer systems must have had approximately the same molecular size as cyclohexane. Also, since the observed specific conductances of the three monomers and that of cyclohexane showed a square-root dependence on the dose rate, they concluded that the behavior of kinetically independent oppositely charged carriers was being observed, with very little effect of the applied field on the recombination process. 

At this point, then, the data appear to indicate that in most of the monomers which have been studied so far—cyclopentadiene, 13-pinene, styrene, a-methylstyrene, isobutylene, and isobutyl vinyl ether—the pre-... 

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