Anionic polymerization asymmetric

Interestingly, Reggelin et al. [147] prepared helical chiral polymers by helix-sense selective anionic polymerization of methacrylates, using an asymmetric base mixture as initiator (Scheme 61). 

Natta carried out the anionic polymerization of methyl sorbate, a 1,3-diene, with an optically active initiator and obtained an optically active homopolymer with main-chain chirality. The high molecular weight crystalline polymer produced with (P)-2-methylbutyllithium had a tritactic (di-iso-rra/w-tactic) structure. This was probably the first metal-catalyzed asymmetric polymerization 134). Polymerization of other dienes was attempted by using various asymmetric methods 135). 

TABLE 11.1. Asymmetric Anionic Polymerization of PFMA with DPEDA-Li Complexes in Toluene at-78cC"... 

Aldehyde Polymers Asymmetric anionic polymerization can lead trichloroacetalde-hyde (chloral) to a one-handed helical, isotactic polymer having a 4/1-helical conformation with... 

Vinyl polymers with a stable helical conformation are obtained from methacrylates with a bulky side group by isotactic specific anionic or radical polymerization.13,34 This type of polymer was first synthesized by asymmetric anionic polymerization (helix-sense-selective polymerization) of triphenylmethyl methacrylate (TrMA, 5) using a complex of n-BuLi with (—( sparteine (Sp, 6).13 Although, as discussed... 

Asymmetric anionic polymerization can convert trichloroacetaldehyde (chloral) to a one-handed helical, isotactic polymer (44) having a 4/1-helical conformation with high optical activity ([oi]d +4000° in film).28114-118 Anionic initiators such as 45,115 46,115 and 47117 and Li salts of optically active carboxylic acids or alcohols are used for the polymerization. Although the polymers are insoluble in solvents and their conformation in solution cannot be directly... 

Ma J-J, Nestegard MK, Majumdar BD, Sheridan MM. Asymmetric star block copolymers anionic synthesis, characterization, and pressure-sensitive adhesive performance. In Quirk RP, editor. Applications of Anionic Polymerization Research. ACS Symposium Series. Volume 696. Washington (DC) American Chemical Society 1998. p 159-166. 

An example of an asymmetric induction from optically inactive monomers in an anionic polymerization of esters of butadiene carboxylic acids with (/ )-2-methylbutyllithium or with butyllithium complexed with (-)-menthyl ethyl ether as the catalyst. The products, tritactic polymers, exhibit small, but measurable, optical rotations. Also, when benzofiiran, that exhibits no optical activity, is polymerized by cationic catalysts like aluminum chloride complexed with an optically active cocatalyst, like phenylalanine, an optically active polymer is obtained. ... 

Sequential monomer addition by using a monofunctional initiator (Figure 3(c)) could be followed only if the reactivity of both monomers is almost the same. The maaoinitiator formed from monomer A can polymerize monomer B and vice versa. Styrene (St) and dienes in anionic polymerization and various methacrylates in anionic or GTP are characteristic examples of this method. The sequential monomer addition route, due to partial termination and/or deactivation reactions, proposed from the addition of three different quantities of monomer allows the synthesis of asymmetric ABA ttiblock copolymers, where the two end blocks exhibit different molecular characteristics. 

An amphiphilic ABCA terpolymer has been prepared by the sequential monomer addition route and modified by postpolymerization reactions. The PSt-PIP-PBd-PSt precursor was synthesized by anionic polymerization followed by hydrogenation of double bonds using Ni-Al catalyst. Accordingly, the PSt outer blocks were sulfonated and neutralized with NaOH. A novel aggregate morphology was achieved in water, showing the influence of the ABCA asymmetric architecture in copolymer self-assembly. ... 

Asymmetric anionic polymerization is carried out using a complex of an organolithium with a chiral ligand or using a chiral organolithium (Figure The helix-sense selection... 

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