Ethylene and styrene copolymerization

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. 

Single-site catalysts offer many new opportunities for copolymerizing ethylene and styrene (Scheme 35). The alternating isospecific polymerization of these... 

Copolymerization of ethylene and styrene by the INSITE technology from Dow generates a new family of ethylene-styrene interpolymers. Polymers with up to 50-wt% styrene are semicrystalline. The stress-strain behavior of the low-crystallinity polymers at ambient temperature exhibits elastomeric characteristics with low initial modulus, a gradual increase in the slope of the stress-strain curve at the higher strain and the fast instantaneous recovery [67], Similarly, ethylene-butylene copolymers may also be prepared. 

These ethylene-based Q and e values may be used to calculate the reactivity ratios for the copolymerization of vinyl acetate with vinyl chloride. Agreement is good when these values are compared with experimental values. In Table IV reactivity ratios calculated from ethylene- and styrene-based Q and e values are shown. 

For the production of ethylene/l-octene copolymers, metallocenes in combination with oligomeric methylalumoxanes or other compounds are now used [31, 63]. Half-sandwich transition metal complexes such as [(tetramethyl- / -cyclopentadienyl) (A-/-butylamido)dimethylsilyl]titanium dichloride are applied to synthesize linear low-density copolymers and plastomers, called constrained geometry catalysts [31]. Ethylene and styrene can be copolymerized to products ranging from semicrystalline mbber-like elastomers to highly amorphous rigid materials at room temperature [64]. 

Smith, G.D. and Boyd, R.H. (1992) Subglass relaxations - Intermolecular packing and the relaxation-times for ester side group reorientation - a Molecular-dynamics simulation. Macromolecules 25,1326-1332. Mani, R. and Burns, C.M. (1991) Homo- and copolymerization of ethylene and styrene using TiCl ... 

Recently, Baird and co-workers have reported (75) examples of polymerizations by a simple mono-Cp titanium complex, (C5(CH3)5)Ti(CH3)3 activated with a Lewis acid (B(C6F5)3) that not only copolymerizes ethylene and a-olefins but also induces polymerization of monomers normally associated with cationic polymerization such as isobutylene and vinyl ethers. Shaffer and Ashbaugh foimd (76) that for isobutylene and a-methylstyrene, the metal complex is an initiator rather than a catalyst (if it even participates at all), but that a transition from cationic to coordination polymerization occurs in styrene polymerization as temperature is raised. Even if it merely functions as an initiator, however, these investigations have revealed new polymerization systems based on anions such as [RB(C6F5)3l (R = alkyl, CeFs) that are less prone to side reactions tending to limit the MW and degree of polymerization of monomers like isobutylene at moderate temperatures (T > -80°C). 

Mani, R. Bums, C. M. Homo- and copolymerization of ethylene and styrene using TiCl3 (AA)/methylaluminoxane. Macromolecules 1991, 24, 5476-5477. 

Miilhaupt and coworkers studied homo- and copolymerizations of 1,5-HD with ethylene and styrene using the MAO-activated constrained geometry catalyst 8. This catalyst system afforded very high 1,5-HD incorporation (reaching 52 mol%) with randomly distributed cis- and transcyclopentane rings in the homo- and copolymer backbones. The ratio of vinyl side chains to cyclic rings was controlled by the 1,5-HD concentration, where low concentrations of 1,5-HD promoted cyclopolymerization. 

Methylalumoxane (MAO) was prepared by the reaction of trimethylaluminum with CuSO 5H2O according to the procedure reported previously.Polymerization of styrene was carried out in toluene (20 ml) in an agitated 100 ml three-necked flask. Both titanium complex and MAO were fed into the flask then stirred for 10 min at polymerization temperature before styrene (10 ml) was added. Polymerization was stopped by adding a mixture of methanol and hydrochloric acid. The polymers obtained were washed with methanol, filtered, and dried in vacuo at 60 C for 4 h. The copolymerization of ethylene and styrene was carried out in a 200 ml three-necked... 

Table 2 shows the results of the copolymerization of ethylene and styrene with various Ti complex-MAO systems. The catalytic... 

COPOLYMERIZATION OF ETHYLENE AND STYRENE UNDER VARIOUS POLYMERIZATION CONDITIONS... 

Table 4 shows the results of the copolymerization of ethylene and styrene under different styrene feed concentrations with the (TBP)Ti(0Pr )2-MA0 system. The catalytic activity as well as the Mw and Mw/Mn increased with increasing styrene concentration. 

Table 4. Copolymerizations of ethylene and styrene with the (TBP)Ti(OPr )2 and MAO system ...

Zhang and Nomura reported on the living copolymerization of ethylene and styrene using a cyclopentadienyl... 

Hydrocarbon resins (qv) are prepared by copolymerization of vinyltoluene, styrene, and a-methylstyrene in the presence of a Eriedel-Crafts catalyst (AlCl ). These resins are compatible with wax and ethylene—vinyl acetate copolymer (197). 

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. 

During this early period, a very ingenious free-radical route to polyesters was used to introduce weak linkages into the backbones of hydrocarbon polymers and render them susceptible to bio degradabihty (128—131). Copolymerization of ketene acetals with vinyl monomers incorporates an ester linkage into the polymer backbone by rearrangement of the ketene acetal radical as illustrated in equation 13. The ester is a potential site for biological attack. The chemistry has been demonstrated with ethylene (128—131), acryhc acid (132), and styrene (133). 

It has been shown by Barb and by Dainton and Ivin that a 1 1 complex formed from the unsaturated monomer (n-butene or styrene) and sulfur dioxide, and not the latter alone, figures as the comonomer reactant in vinyl monomer-sulfur dioxide polymerizations. Thus the copolymer composition may be interpreted by assuming that this complex copolymerizes with the olefin, or unsaturated monomer. The copolymerization of ethylene and carbon monoxide may similarly involve a 1 1 complex (Barb, 1953). 

Polystyrene-g-poly(ethylene oxide) was synthesized by the copolymerization of styrene and styrenic PEO with CpTiCb/MAO catalyst [190]. In this case the macromonomer was prepared by first reacting the sodium salt of PEO-OH with NaH and then with a 5-fold amount of p-chloromethyl styrene. 

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