Styrene, vinyl aromatics

NMP is most commonly used for S polymerization. For S polymerizations carried out at temperatures greater than 100 °C, thermal initiation provides some rate enhancement and a mechanism for controlling the excess of nitroxide that is formed as a consequence of radical-radical termination and the persistent radical 

Various substituted styrenes have been also polymerized by NMP. These include 103-107, p-chloromethylstyrene (108),/i-halostyrenes, and p- 

NMP willi acrylates and acrylamides with TEMPO provides only very low conversions. Very low limiting conversions and broad dispersities were 

64) and isoindoline (59) nitroxides. However, limiting conversions were still observed. Tlie self-regulation provided in S polymerization by thermal initiation is absent and, as a consequence, polymerization proceeds until inhibited by the buildup of nitroxide. The final product is an alkoxyamine and NMP can be continued 

uch better control is obtained with the open chain nitroxides, in particular 86 and jj9where mnch lower reaction temperatures can be used and high conversions are achieved. 

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Some of the styrene-vinyl aromatic compound copolymers also demonstrate isomorphism 175). The best examples are styrene-o-F-styrene copolymers, which are highly crystalline products with melting points in the 235-270° C range. The helix bands in the IR spectra of the copolymers disappear, beginning from the 30% content of another comonomer, confirming random copolymerization 175). 

In order to increase the solubiUty parameter of CPD-based resins, vinyl aromatic compounds, as well as other polar monomers, have been copolymerized with CPD. Indene and styrene are two common aromatic streams used to modify cyclodiene-based resins. They may be used as pure monomers or contained in aromatic steam cracked petroleum fractions. Addition of indene at the expense of DCPD in a thermal polymerization has been found to lower the yield and softening point of the resin (55). CompatibiUty of a resin with ethylene—vinyl acetate (EVA) copolymers, which are used in hot melt adhesive appHcations, may be improved by the copolymerization of aromatic monomers with CPD. As with other thermally polymerized CPD-based resins, aromatic modified thermal resins may be hydrogenated. 

The catalytic asymmetric aminohydroxylation of a variety of styrene derivatives, vinyl aromatics, and some other olefins using osmium tetroxide... 

Only a limited number of monomer pairs form block copolymers in this manner. Examples are conjugated dienes and vinyl aromatics that have similar Q-e values. The nature of the anionic initiator, i.e., the ionic character of the carbon-metal bond plays an important role in both the amount and sequence of block formation. For instance, when potassium or cesium initiators are used, styrene polymerizes first as can be seen in Figure 12. 

Little plasticizer is used commercially with styrene polymers. To investigate the interaction between ethylene oxide and vinyl aromatic polymers has been the objective of J. Moacanin and co-workers. 

Styrene An aromatic compound refined from petroleum with the chemical formula C8H8. Also known as vinyl benzene and phenethylene. Styrene is used in the manufacture of polystyrene and synthetic rubber. 

Instead of block copolymers, the use of pseudo-random linear copolymers of an aliphatic a-olefin and a vinyl aromatic monomer has been reported [20], where the styrene content of the polymer must be higher than 40 wt%. Preferred are styrene and ethylene copolymers. These blends may contain, amongst other things, an elastomeric olefinic impact modifier such as homopolymers and copolymers of a-olefins. Presumably the styrene-ethylene copolymer acts as a polymer emulsifier for the olefinic impact modifier. Using 5 wt% of an ethylene-styrene (30 70) copolymer and 20% of an ethylene-octene impact modifier in sPS, a tensile elongation (ASTM D638) of 25 % was obtained. 

Studies of ethylene-vinyl aromatic monomer polymerizations continue to be published. Chung and Lu reported the synthesis of copolymers of ethylene and P-methylstyrene [28] and the same group extended these studies to produce and characterize elastomeric terpolymers which further include propylene and 1-octene as the additional monomers [29,30]. Returning to the subject of alternative molecular architectures for copolymers, Hou et al. [31] has reported the ability of samarium (II) complexes to copolymerize ethylene and styrene into block copolymers. 

It is of interest to note that within the limit of acoiracy of these experiments, monomer decay curves (Fig. 22) were single exponential, whereas Sdieme 1 predicts dual exponentiality (Eq. 65). The results thus imply that in pdyslyrene reverse dissociation ( feedback ) of the excimer is not of importance. This point is amplified by time-resolved fluorescence spectra which show that late- ted >ecti a (see experimental section) are composed exclusively of excimer emission (Fig. 23). The same is true in poly(a-methylstyrene) In view of more recent work mi other vinyl aromatic ptdymers, it would be of interest to study pdy(styrene) further with more sophisticated techniques. 

In helium quantitative yield of HCI. remainder residue and hydrocarbons, benzene is major volatile hydrocarbons product aliphatic hydrocarbons, benzene (major product), toluene, ethylbenzene, o-xyiene, monochlorobenzene styrene, vinyl tcriuerre. p-dichlorobenzene, o-dichlorobenzene, indene, 1,3.5-trichlorobenzene 1.2.4. richlorobenzene. naphthalene, u-methylnaphthalene. p-methylnaphthatene effect of ZnO. SnOj, and Ab03 on the yields of products Is also recorded HCI. CO2. ethene. ethane, propane, 1-butene. 2-butene. 1-pentene. cydopentene, n-pentane, 2-methylbulane, 1,3-pentadiene. 2-methyl-1,3-pentadiene, complex series (60 Identlfled) of aromatic and polyaromatic species including benzene, styrene, methylstyrenes, toluene, o-xytene, m-xylene, p-xylene, biphenyl, naphthalene, anthracene, phenanthrene. pyrene, etc. 

The conversion of a-methylstyrene (2-phenyl- 1-propene) also serves as a model reaction in many other investigations of asymmetric hydrocarboxylation. Due to its high regioselectivity and low tendency for alkene isomerization, only the linear reaction product is formed (> 95 %) together with minor amounts of the achiral branched product. With styrene itself, and other vinyl aromatics generally lower regioselectivities are observed. The results of asymmetric hydrocarboxylation of this substrate type are compiled in Table 10. 

Table 10. Asymmetric Hydrocarboxylation of Styrene and Other Vinyl Aromatics... 

Many other chiral phosphane ligands are used in asymmetric hydrocarboxylation. In the presence of NMDPP and trifluoroacetic acid in methanol carbomethoxylation of vinyl aromatics. in particular styrene, with palladium(0)bis(dibenzylidcncacetone) takes place with marked asymmetric induction (up to 52% cc) and high selectivities towards the branched product (94%)20. With other chiral ligands and other acids only smaller inductions are observed using the same catalytic system. With an increase in carbon monoxide pressure the asymmetric induction decreases. Involvement of the complex PdH(PR3),OCOCF3 is presumed20. 

TABLE 11. Quantum Yields for the Irradiation of Poly(styrene-co-vinyl Aromatic Ketones)s at 313 nm in Nj... 

Ionic polymerization systems of commercial importance employ mostly batch and continuous solution polymerization processes. Suitable monomers for ionic polymerization include conjugated dienes and vinyl aromatic. Among these, the anionic polymerization of styrene-butadiene (SB) and styrene-isoprene (SI) copolymers and the cationic polymerization of styrene are the most commercially important systems. 

More recently, a US Patent has been issued to the Goodyear Tire Rubber Company, which claimed that polar functional monomers could be copolymerized with conjugated dienes and vinyl aromatics to chemically modify the polymer chain. Functional monomers, such as 3-(2-pyrrolidinoethyl) styrene ... 

Production of EPS. Plastic materials on the polystyrene basis occupy with its production volume the third position in the world, following polyolefin and pol5rvinyl chloride. Polystyrene (PS) is made from styrene (vinyl benzene), which is liquid at ordinary temperatures and can be polymerized well in a unit or suspension. In the basic methylene chain, which forms a polystyrene molecule, a six-part aromatic circle (phenyl) is linked to every other carbon instead of hydrogen. 

Polyolefin, PO [of ethylene, propylene, butylene, 4-methylpentene, and their copolymers with 1-aUcenes, vinyls, (meth)acrylates - preferably PP], was grafted at a ratio 1 9-4 1 with 1-20 wt% of (meth)acrylic acid and >30 wt% of styrene and/or aUcyl- and/or halo-substituted styrene, methacrylic ester, and 0-60 % of other comonomers [e.g., vinyl aromatic, ester], at least some of the acid units of methacrylic acid and/or acrylic acid bearing a charge and being associated with non-polymeric counterions [e.g., 90 % methyl methacrylate, 5 % butyl acrylate, and 5 % methacrylic acid with either or Mg ". The ionomer could be blended with PO either during or after manufacturing. 

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