Benzene anionic copolymerization

Mixed dimerization also affects the kinetics of anionic copolymerization of styrene and para-methyl styrene, a system studied by O Driscoll(24). The reaction was performed in benzene with lithium counter-ions and the plots of In.[styrene] or In(para-methyl styrene] vs. time were both linear. Their slopes,... 

Anionic copolymers, trans-stilbenebutadiene copolymer, trans-stilbene-isoprene copolymer, and trans-stilbene-2,3-dimethylbutadiene copolymer, copolymerized using BuLi initiator, were studied in THE at 0°C and in benzene at 40°C [89]. It was shown that the rate of monomer consumption (excluding stilbene) decreased as follows butadiene > isoprene > 2,3-dimethylbutadiene. Anionic copolymerization... 

The anionic copolymerization of styrene and l-(4-dimethylaminophenyl)-1-phenylethylene in benzene has been investigated [188]. As discussed previously in Sect. 5, Yuki and coworkers [125, 126, 129, 133-136] have developed the formalism for analyzing the kinetics of copolymerization of 1,1-diphenylethylene (M2) with styrene and diene monomers (Mi). It was assumed that the 1,1-diphenylethylene derivative, M2, does not add to itself due to steric effects, i.e., k22=0, as discussed previously in Sect 5. Thus, the monomer reactivity ratio for M2 is zero, i.e., r2- 22l ii- - It was also assumed that the styrene monomer is completely consumed at the end of the polymerization... 

It was anticipated that the copolymerization of substituted 1,1-dipheny-lethylenes with dienes such as butadiene and isoprene would be complicated by the very unfavorable monomer reactivity ratio for the addition of poly(-dienyl)lithium compounds to 1,1-diphenylethylene [133, 134]. Yuki and Oka-moto [133, 134] calculated values of ri=54 and ri=29 in hydrocarbon solutions for the copolymerization of 1,1-diphenylethylene (M2) with butadiene (Mi) and isoprene (Mi), respectively. Although the corresponding values in THE are ri(butadiene)=0.13 and ri(isoprene)=0.12, this would not be an acceptable solution since THE is known to form polymers with high 1,2-microstructures [3]. Anionic copolymerizations of butadiene (Mi) with excess l-(4-dimethyla-mino-phenyl)-l-phenylethylene (M2) were conducted in benzene at room temperature for 24-48 h using scc-butyllithium as initiator [189]. Anisole, triethy-lamine and ferf-butyl methyl ether were added in ratios of [B]/[RLi]=60, 20, 30, respectively, to promote copolymerization and minimize 1,2-enchainment in the polybutadiene units. Narrow molecular weight distribution copolymers with Mn=14xl0 to 32x10 (Mw/Mn=1.02-1.03) and 8, 12, and 30 amine... 

As was stated above, the interpretation that the field affects the dis-sodation state of the growing chain ends was not uniquely substantiated by the experimental data, except those on copolymerizations. Thus it is interesting to investigate the field influence on much simpler systems than cationic homopolymerizations. For this purpose we have chosen living anionic systems in which only propagation steps are involved. The system first studied was a living anionic polymerization of styrene with n-butyllithium in the binary mixtures of benzene and tetrahydrofuran (17,24) and in the binary mixtures of benzene and dimethoxyethane (15). 

Inone, Tsuruta and J. Furukawa (29) have investigated the unusual catalyst system prepared from calcium and diethyl zinc. They claimed that a reaction occurred according to the following equation Ca + 2 ZnEtg -> CaZnEt4 + Zn. Such a catalyst system is heterogeneous in benzene or in bulk, and produces a polystyrene containing 13% of a crystallizable fraction. The catalyst also polymerizes methyl methacrylate, and the anionic nature of these processes is indicated by the reactivity ratios for styrene (Mj) and methyl methacrylate (Mg) copolymerization, rx = 0.31, r2 = 17.1. 

Several attempts at the free-radical (benzene, 1% AIBN, 100 h, 55 °C) and anionic (1 4 THF-benzene, n-butyllithium-18-crown-6 complex [16, 17], -78 °C) polymerization of IPTMSK afforded only traces (<2 %) of a viscous product. Free-radical copolymerization of IPTMSK with methyl methacrylate (MM A) (50 mol % MM A, benzene, 0.5% AIBN, 100 h, 45 °C) resulted in a low yield (<10 %) of a copolymer composed mainly of MMA units and, as indicated by the IR (Figure 1C) and NMR data, of largely decomposed IPTMSK units. The presence of IPTMSK during copolymerization with MMA significantly decreased the molecular weight of the resulting copolymer. These results suggest that IPTMSK is incapable of homopolymerization by either a free-radical or an anionic mechanism. 

It has been reported that vinylferrocene is polymerized by using a radical, cationic, anionic, or Ziegler system initiator [29 — 34]. In particular, higher molecular weight products can be obtained using radical-initiated bulk polymerization [31]. Indeed, both bulk copolymerization and solution copolymerization (in benzene) of 18 with vinylferrocene by using a radical initiator (AIBN) afforded the chiral polymers 19a —e (Scheme 3-13), which were purified by reprecipitation of the benzene solution with methanol. The ratios of the two comonomers were varied in copolymerization. The composition data of the copolymers obtained revealed nearly the same reactivity between 18 and vinylferrocene, which suggests that 19a—e are random copolymers. 

A macromonomer technique was employed by Ishizu and Kuwahara to prepare miktoarm star copolymers of the (PS) (PI)m type.128 PS and PI macromonomers were prepared by coupling the living chains with />chloromethylstyrene. The PS and PI macromonomers (vinyl end-capped chains) were copolymerized anionically in benzene using n-BuLi as initiator. The products are comb-shaped copolymers, but they behave as miktoarm stars of the type A Bm. The reaction sequence is given in Scheme 58. 

Attempts to copolymerize 15 with styrene in an analogous manner failed due to decomposition of the cluster. However, copolymerization was accomplished by use of n-butyl lithium as an anionic initiator. In this case, a benzene solution of styrene and 15 (in a 100/1 mole ratio) was treated with a trace of n-butyl lithium. After 20 hours, methanol was added to the mixture in order to quench the reaction and cause precipitation of the resulting polymer, which was then purified by repeated precipitations from methylene chloride. Spectroscopic characterization of the polymer confirmed that the cluster had been chemically incorporated into the polymer, with a loading of 0.67 mole per cent. 

Hashimoto and coworkers smdied anionic living copolymerization by ionic mechanism of two monomers, styrene and isoprene in a dilute benzene solution with the aid of combined time-resolved... 

Myrcene is, to our knowledge, the only monoterpene which has been the object of living anionic polymerization (LAP) and copolymerization studies [91]. These systems involved A -butyl lithium as the initiator, and either benzene or THF as solvent. When the reaction was carried out in the former, 1,4-addition was favoured (85-90 per cent). 

A comprehensive list of the grafting reactions of (a) and (b) onto different polymer backbones is given in Ref 543. The methods summarized there include radiation techniques [623], grafting by radical transfer [624], and grafting initiated by functional groups in backbone polymers [625,626]. Macromonomers of (a) have been synthesized by means of anionic polymerization techniques and have been copolymerized with styrene [627,628]. Only a few examples are known in which polymers from (a) and (b) were used as backbone [629]. Star shaped block copolymers with four arms were prepared by coupling living styrene/(a) block copolymers with 1,2,4,5-tetrakis-bromomethyl-benzene [626]. 

Studies of the copolymerizations of 1,1-diphenylethylene and dienes showed rather different behavior compared with the copolymerizations of styrene and 1,1-diphenylethylene [125, 133-136]. The monomer reactivity ratios for copolymerizations of dienes with DPE are shown in Table 7. When butadiene was copolymerized with 1,1-diphenylethylene in benzene at 40 °C with -butyl-lithium as initiator, the monomer reactivity ratio for butadiene, ri, was 54 this means that the addition of butadiene to the butadienyl anion is 54 times faster than addition of 1,1-diphenylethylene to the butadienyl anion [133]. This unreactivity of poly(butadienyl)lithium towards addition to DPE was also observed in studies of end-capping of poly(butadienyl)lithium with DPE in hydrocarbon solution (see Sect.3.3) [109, 111]. Because of this unfavorable monomer reactivity ratio, few DPE units would be incorporated into the co-... 

Free radical or anionic polymerization is possible and can gel using a crosslinking agent (N,N -methylene bis acrylamide, divinyl benzene, etc.) that has a multifunctional group. Various copolymerized crosslinked materials can be obtained by comonomers. 

Polystyrene is imusual among commodity polymers in that we can prepare it in a variety of forms by a diversity of polymerization methods in several types of reaction vessel. Polystyrene may be atactic, isotactic, or syndiotactic. Polymerization methods include free radical, cationic, anionic, and coordination catalysis. Manufacturing processes include bulk, solution, suspension, and emulsion polymerization. We manufacture random copolymers by copolymerizing styrene directly vith comonomers containing vinyl groups. In addition, we can polymerize styrene in the presence of polymer chains containing unsaturation in order to create block copolymers. Crosslinked varieties of polystyrene can be produced by copolymerizing styrene vith difunctional monomers, such as divinyl benzene. 

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