Anionic Polymerization of 1,3‐Cyclohexadiene: Reactivity of Poly(1,3‐cyclohexadienyl)lithium

Abstract

Summary: The reactivity of poly(1,3‐cyclohexadienyl)lithium (PCHDLi), as a species for the propagation of the anionic polymerization of 1,3‐cyclohexadiene (1,3‐CHD), was examined using a post‐polymerization reaction of PCHDLi and 9‐bromofluorene (9‐BFL). The degree of nucleophilicity of the PCHDLi systems was determined as PCHDLi/1,4‐diazabicyclo[2,2,2]octane (DABCO) > PCHDLi/N,N,N′,N′‐tetramethylethylenediamine (TMEDA) > PCHDLi. The nucleophilicity of PCHDLi was strengthened by the complexation of TMEDA to Li, and was saturated when the TMEDA/Li molar ratio was over 1.0. The rate of polymerization increased with increasing nucleophilicity of PCHDLi. In addition, the molar ratio of the 1,2‐addition (1,2‐CHD unit)/1,4‐addition (1,4‐CHD unit) seemed to be strongly affected by both the nucleophilicity of PCHDLi and the steric hindrance of CLi bonds in PCHDLi.Post‐polymerization reaction of poly(1,3‐cyclohexadienyl)lithium (PCHDLi) and 9‐bromofluorene (9‐BFL).magnified imagePost‐polymerization reaction of poly(1,3‐cyclohexadienyl)lithium (PCHDLi) and 9‐bromofluorene (9‐BFL).

The rapid, living, anionic polymerization of 2‐vinylnaphthalene at ambient temperature: Characterization of an n‐butyllithium/tetrahydrofuran system in 1,2,3,4‐tetrahydronaphthalene

“…As we reported in previous papers, the type of RLi, the solvent and addition of a polar additive will all greatly affect the anionic polymerization of 1,3‐cyclohexadiene (1,3‐CHD; a diene monomer) and 4‐diphenylaminostyrene (4‐DAS; a St derivative) at ambient temperature . These studies further demonstrated that the application of a suitable polymerization system resulted in the first‐ever instance of well‐controlled (i.e., living) anionic polymerization of 1,3‐CHD and 4‐DAS .…”

End-group stannylation of regioregular poly(3-hexylthiophene)s

“…TMEDA has been reported to enhance the polarity of alkyllithium species or to break them into smaller clusters, leading to higher reactivity and faster metalation. 18,19 Thus, we have conducted the lithiation of P3HT in the presence of TMEDA. The 1 H NMR spectrum recorded after stannylation shows that the addition of TMEDA to the lithiation process resulted in the formation of stannylated P3HT (see Figure 2 for a typical 1 H NMR spectrum), as indicated by the presence of a characteristic -CH 3 peak at d ¼ 0.40 in the Me 3 Sn-group.…”

Anionic polymerization of 1,3‐cyclohexadiene: Addition of poly(1,3‐cyclohexadienyl)lithium to fullerene‐C60

“…We previously reported that the structure of the PCHD carbanion can be predicted from the polymer chain structure, that is, we proposed the existence of a covalent σ‐structure [Scheme (a)] and an ionic π‐structure [Scheme (b)] as PCHD carbanions in PCHDLi from the analogous poly(butadienyl)lithium 20, 29. The σ‐ and π‐forms of PCHDLi are considered to result in 1,4‐addition (1,4‐CHD unit) [Scheme (c)] and 1,2‐addition (1,2‐CHD unit) [Scheme (d)], respectively.…”

“…We have previously revealed that three types of polymer main chain structures, such as an all 1,2‐CHD unit sequence [Scheme (a)], a 1,2‐CHD/1,4‐CHD unit sequence [Scheme (b)], and an all 1,4‐CHD unit sequence [Scheme (c)] can be formed in PCHD 14, 15, 18–37…”

“…In the previous articles,18–37 we reported the first successful example of the (living) anionic polymerization of 1,3‐cyclohexadiene (1,3‐CHD), a monomer of PCHD. Subsequently, a well‐defined C 60 ‐PCHD having a maximum of four arms was synthesized by the addition of poly(1,3‐cyclohexadienyl)lithium (PCHDLi) to C 60 (Scheme ) 14, 15.…”