Kinetic studies and reaction mechanisms in homogeneous anionic polymerization

Abstract

Abstract

Anionic polymerization of MMA initiated by organolithium/cuprum diphenylphosphide (Ph2PCu) and synthesis of its block copolymer

“…Organolithium/cuprum diphenylphosphide (RLi/ Ph 2 PCu) complexes have better thermal stability and initiation reactivity than RLi/CuSCN and RLi/ PhOCu. Among the three kinds of RLi/Ph 2 Pcu studied, the polymerization of alkyl methacrylate initiated by n-BuLi/Ph 2 PCu and Ph 2 PCu/Li(Ip) [3][4][5][6] Li/ Ph 2 PCu in THF at À50 C showed partial living characteristics. This finding is demonstrated by the following: (a) the narrow MWD (1.08-1.25), 100% initiation efficiency; (b) the linear relationship between the experimental number average molecular weight and [MMA]/[n-BuLi/Ph 2 PCu]; (c) the proportional increase in molecular weight; and (d) the constant narrow distribution after multiple monomer additions.…”

“…It suggests excessive feeding times for the synthesis of segmented copolymer, making it difficult to prepare the symmetrical ABA block copolymer. Thus, dilithium oligomer of isoprene 49,50 was used to prepare dilithium heterocuprates, i.e., Ph 2 PCu/Li(Ip) [3][4][5][6] Li/Ph 2 PCu. It initiated MMA to polymerize bidirectionally (Scheme 4).…”

“…The living character of the Ph 2 PCu/Li(Ip) [3][4][5][6] Li/ Ph 2 PCu initiated polymerization was used to prepare the segmented copolymer PGMA-b-PBMA-b-PMMA- b-PBMA-b-PGMA. The synthetic route is illustrated in Scheme 4.…”

“…However, the ideal anionic living polymerization of alkyl methacrylate has not yet been developed because of the inherent side reactions of the polar ester group 2. All the reactions during both initiation and propagation have been investigated in detail and many methods have been attempted to suppress the side reactions 2–15. The breakthroughs achieved thus far include group transfer polymerization (GTP) of silyl ketene acetal and metal‐free anionic polymerization (MFA), which were developed in the 1980s 16–18.…”

“…2 All the reactions during both initiation and propagation have been investigated in detail and many methods have been attempted to suppress the side reactions. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] The breakthroughs achieved thus far include group transfer polymerization (GTP) of silyl ketene acetal and metal-free anionic polymerization (MFA), which were developed in the 1980s. [16][17][18] In addition to GTP and MFA, classical anionic polymerization can also show living characteristics with ligands capable of coordinating with enolate ion pairs.…”