Living Anionic Polymerization of 4-Halostyrenes

Abstract

Anionic polymerizations of 4-chlorostyrene (1), 4bromostyrene (2), and 4-iodostyrene (3) were carried out in tetrahydrofuran (THF) at −78 °C for 5 min using sec-butyllithium (sec-BuLi) or oligo(α-methylstyryl)lithium (αMSLi) as the initiator. Poly(1)s having broad molecular weight distribution (MWD, Đ M , M w /M n ∼2) were quantitatively obtained using sec-BuLi and αMSLi, and the molecular weights could be controlled by the molar ratios between 1 and the initiators. Complete consumption of 2 was also realized using αMSLi under similar conditions. The conversion of 2 was only 8.8% when initiated with sec-BuLi, and the resulting poly(2) possessed broad multimodal MWD. No polymeric product of 3 was produced using sec-BuLi, indicating the presence of major side reactions involving the electrophilic C−Br and C−I bonds. On the other hand, well-defined poly(1) and poly(2) were quantitatively obtained using αMSLi in the presence of 10-fold cesium phenoxide (PhOCs) as an additive. The polymerization using αMSLi/PhOCs was completed within few minutes, and the resulting poly(1)s and poly(2) possessed narrow MWD (M w /M n <1.1) and predictable molecular weights. In the case of 3, the αMSLi/PhOCs initiator quantitatively produced poly(3) having predictable molecular weight and relatively narrow MWD (M w /M n = 1.2−1.3). The stability of the propagating carbanions was demonstrated at −78 °C by the quantitative efficiency of the sequential copolymerization of 1 or 2 and styrene as well as that of 1 and 2 in any addition order. The observed difference in polymerization behaviors of 1−3 can be explained by the relative reactivity of the carbon−halogen bonds in the monomer structures.

Quo Vadis Carbanionic Polymerization?

“…Many synthetic groups were focused on discovering and studying new vinyl monomers compatible with anionic polymerization, leading to the synthesis of novel materials with exciting properties. − Ishizone’s − and Ma’s , groups, reported the synthesis of several novel styrene and 1,3-diene derivatives bearing various substituents. For example, the anionic polymerization of styrene derivatives with bulky adamantyl groups generated well-defined polymers exhibiting higher T g values (>200 °C) than PS .…”

Characterization and kinetics study of poly(α-methyl styrene) synthesized by living anionic polymerization

“…Well-de ned poly(methyl styrene-co-styrene) copolymers were synthesized by Wolf et al [11]. 13 C NMR of quaternary aromatic carbon showed diad probabilities and synthetic pathway to favor alternating sequences. The combination of living cationic polymerization and anionic ring-opening polymerizations (AROP) has been used to synthesize linear triblock copolymers containing PAMS, polyisobutylene, and polypivalolactone [12].…”

“…The combination of living cationic polymerization and anionic ring-opening polymerizations (AROP) has been used to synthesize linear triblock copolymers containing PAMS, polyisobutylene, and polypivalolactone [12]. Goseki and coworkers suggested oligo (α-methyl styrene) lithium as the initiator for synthesis of 4halostyrenes via anionic polymerization [13].…”

“…Moreover, multi-stage dosing of initiator offers valuable and accurate method to determine propagation rate constant and initial impurities value of the system. 13 C NMR analysis demonstrated that Bernoullian statics model exhibits a superior t compared to 1storder Markov statics model for the assigned sequence. Furthermore, the synthesized PAMS presents higher degree of racemic addition with P m =0.439.…”

Synthesis of Sequence-Controlled Homopolymer via Anionic Self-Alternating and Chemoselective Polymerization of 4-Vinyl-1,1-diphenylethylene Derivatives

“…In this study, a series of novel VD derivatives possessing specific substituents, chloro ( ClVD ), methyl ( MeVD ), methoxy ( MeOVD ), and dimethylamino ( Me2NVD ) groups at the para -position of the DPE framework, were designed and synthesized by considering the Hammett parameters (Scheme ). It is noted that the corresponding 4-substituted styrene derivative was used for anionic polymerization, which indicates the tolerance of these substituents to basic conditions. − A characteristic feature of VD is that the entire molecule is connected by an extended π-conjugated system. Therefore, the electronic effect of the substituent on the DPE skeleton of VD is anticipated to change the reactivity of both the monomer and its generated carbanion.…”