Lithium polybutadienyl

This unusual behavior was accounted for by O Driscoll and Kuntz411), who postulated an extremely fast addition of butadiene to lithium polystyryl but slow addition of styrene to lithium polybutadienyl. Such a relation prevents the formation of any significant proportion of lithium polystyryl in the polymerizing system as long as butadiene monomer is available. Since the homopolymerization of butadiene is relatively slow, whereas that of polystyrene is rather fast, the polymerization speeds up as butadiene disappears. 

The temperature dependency of 1,2 content shown in Table II is also consistent with complex formation between polybutadienyl-lithium and the oxygen atom in the lithium morpholinide moleculre. One can visualize an equilibrium between noncom-plexed and complexed molecules which would be influenced by temperature. Higher temperatures would favor dissociation of the complex and, therefore, the 1,2 content of the polymer would be lower than that from the low temperature polymerization. This explanation is supported by the polymerization of butadiene with lithium diethylamide, in which the microstructure of the polybutadiene remains constant regardless of the polymerization temperature (Table IV). This is presumably due to the fact that trialkylamines are known to be poor... 

End-functionalized polyethylene (PE) [8, 9], polypropylene (PP) [10], and polyisobutylene (PIB) [11] have been transformed to their corresponding macromonomers carrying (meth)acrylate, oxazoline, and methacrylate end groups, 1, 2, and 3, respectively. Polybutadienyl lithium was terminated with chlo-rodimethylsilane, followed by hydrogenation to saturated polyolefin (PHBd) [12]. Hydrosilylation of the end silane with allyl glycidyl ether afforded an epox-... 

Reiteration ultimately leads to a generation = 4 stage dendrimer possessing as many as 64 silicon chloride or vinyl surface groups. These dendrimers have been utilized as macromolecular termination templates for quenching polybutadienyl lithium to give 64 armed star polymers. 

With butadiene and isoprene, the orders in lithium alkenyl are near one quarter (or perhaps even one sixth for butadiene [52, 63]). Data exists where the reported order is nearer one half [59, 66], characterized by rates which are close to those given in Fig. 10 at initiator concentrations near 10 M, but which become much lower as the concentration is decreased. In one case, later work has indicated that this is caused by increased initiator destruction at low concentrations and it seems reasonable to suppose that this explanation is valid for the whole group of experiments. Comparison of kinetic order with degree of association is hindered by the fact that there is no agreement as to the association number of polybutadienyl or polyisoprenyllithium, it being variously described as two [32, 60] or near four [33, 61]. The association phenomenon, however, undoubtedly plays a role in the observed kinetics. 

It has been shown by - C-NMR spectroscopy that the reaction of alkyl lithium species with butadiene to form the substituted butenyl compounds gives a mixture of the anti and the syn isomers, with the latter being the more stable one [43] for the polybutadienyl- and polyisoprenyllithium compounds in hydrocarbons a dimeric association has been proved [41, 44]. 

Odian, G., 2004b. Principles of Polymerization, 4th ed. Wiley-Interscience, Hoboken, New Jersey. OhUnger, R., Bandermann, F., 1980. Kinetics of the propagation reaction of butadiene-styrene copolymerization with Uthium-a-ganic compounds. Macromol. Chem. 181 (9), 1935-1947. Oishi, Y., Watanabe, H., Kanaya, T., et al., 2006. Dynamics of monofunctional polybutadienyl lithium chains aggregated in benzene. Polym. J. 38 (3), 277-288. 

By far the most common initiator for copolymerization of styrene and butadiene is butyl lithium. Once the polymerization process is initiated, the tendency of the anionic species to add to butadiene or styrene monomer will be different. The polybutadienyl anion prefers to react with another butadiene monomer rather... 

The presence of cross-associates needs to be considered in the interpretation of copolymerization kinetics. It has been found that the reaction of poly-butadienyl-lithium with /Mlivinylbenzene in benzene solution proceeds at a rate which increases very markedly with time. Such a result would seem to imply that the polybutadienyl-lithium dimer is very much less reactive than is the mixed dimer formed between polybutadienyl-lithium and the vinylbenzyl-lithium generated by its reaction with p-divinylbenzene. Interestingly, no accelerations... 

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