Styrene preparation

Variation of Styrene Content with Extent of Conversion. Figure 8 gives the relationship between copolymer composition and the extent of conversion for copolymers of butadiene and styrene (25 wt.7. styrene) prepared in toluene, at 30°C, with n-BuLi and barium salts of t-butanol and water. For comparison purposes, the copolymer composition curve is shown for the reaction initiated using n-BuLi alone. Copolymerization using n-BuLi results in very little incorporation of styrene into the copolymer chain until about 757. conversion, after which the styrene content increases very rapidly. In contrast, copolymerization using the barium salts and n-BuLi results in an increased incorporation of styrene at the same extents of conversion. 

Butadiene-Styrene Copolymers from Ba-Mg-Al Catalyst Systems. Figure 13 shows the relationship between copolymer composition and extent of conversion for copolymers of butadiene and styrene (25 wt.7. styrene) prepared in cyclohexane with Ba-Mg-Al and with n-BuLi alone. Copolymerization of butadiene and styrene with barium salts and Mg alkyl-Al alkyl exhibited a larger initial incorporation of styrene than the n-BuLi catalyzed copolymerization. A major portion of styrene placements in these experimental SBR s are more random however, a certain fraction of the styrene sequences are present in small block runs. 

Dynamic viscoelastic and stress-optical measurements are reported for blends of crosslinked random copolymers of butadiene and styrene prepared by anionic polymerization. Binary blends in which the components differ in composition by at least 20 percentage units give 2 resolvable loss maxima, indicative of a two-phase domain structure. Multiple transitions are also observed in multicomponent blends. AU blends display an elevation of the stress-optical coefficient relative to simple copolymers of equivalent over-all composition. This elevation is shown to be consistent with a multiphase structure in which the domains have different elastic moduli. The different moduli arise from increased reactivity of the peroxide crosslinking agent used toward components of higher butadiene content. 

Homopolymer PS and block copolymer poly(tert-butyl acrylate)-b-styrene, prepared by nitroxide-mediated living free-radical polymerization, were utilized for the functionalization of shortened SWCNTs through a radical coupling reaction (Scheme 1.33) [194]. 

Some color due to small amounts of iodine may be present in substituted styrenes prepared by this procedure from aryl-methylcarbinols synthesized from the corresponding aldehyde and methylmagnesium iodide. If present, iodine may be removed by shaking the crude product with 1 g. of powdered zinc and 25 ml. of water. 

Many adducts 1 of dibromocarbene to ring-substituted styrenes prepared using bromoform/potassium /crt-butoxide have been described (unfortunately, the yields were not given). 

The a-methyl resonance in poly(o -methyl styrene) is found to be split into three peaks which are assigned to isotactic, heterotactic and syndiotactic triads. Fractions of the polymers in the three configurations determined by the area of these peaks are given below for poly(o -methyl styrene) prepared with two different catalysts [S. Brownstein, S. Bywater, and D. J. Worsfold, Makromol. Chem., 48, 127 (1961)] ... 

Moad et al. reported that, for the copolymer of MMA and styrene prepared with 13C=0-labelled BPO, C=0 carbon showed clear splittings not only due to the difference of the first monomer unit but also due to the second monomer unit.86 Detailed analysis of the sequences may afford monomer reactivity ratios at the beginning of the copolymerization. 

Figure 2. Aliphatic proton resonance (100 MHz) of styrene-methyl methacrylate copolymers in CeD9 solution at 80°C containing 49 mol % of styrene derived from a styrene-methacrylic anhydride copolymer (top), and containing 56 mol % styrene prepared directly from styrene and methyl...

The superior cold properties of lithium polymers were even more pronounced in the case of butadiene-styrene copolymers than in the poly butadienes. As Figure 2 shows, a butadiene-styrene copolymer (33% styrene) prepared with lithium outperformed LTP (23.5% styrene, emulsion recipe, 5°C.) by 21 °C. in regard to the temperature at which Young s bending modulus reaches 10,000 pounds per square inch. The fact that the lithium polymer had a higher styrene content and also a higher Mooney viscosity (130 vs. 49) than LTP should have affected its cold properties adversely therefore, the superior performance of the lithium copolymer is significant. 

Many derivatives of styrene can be readily synthesized. Some are commercially available. One of them is a-methyl styrene. It is formed from propylene and benzene by a process that is very similar to styrene preparation ... 

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