Effect of lithium perchlorate on the spontaneous copolymerization of 4-vinylpyridine with various electron-rich vinyl monomers

Autor: Choi, Woon-Seop, Mikhael, Michael G., Padias, Anne B., Hall, H. K.
Zdroj: Journal of Polymer Science Part A: Polymer Chemistry; 1 June 1999, Vol. 37 Issue: 11 p1709-1716, 8p
Abstrakt: The spontaneous copolymerization of 4-vinylpyridine (4-VP) activated with lithium perchlorate (LiClO4) with various electron rich monomers (p-methoxystyrene, MeOSt; p-methylstyrene, MeSt; styrene, St) was investigated in various solvent systems at 75°C. Increasing the LiClO4 concentration and the nucleophilicity of the electron rich monomer increased the copolymer yields. Both 1H-NMR and elemental analysis confirmed the almost 1:1 copolymer structure for VP/MeOSt system which possessed high molecular weight and narrow polydispersity (PDI). Compared to 4-VP activated with zinc chloride, LiClO4 systems showed slightly lower yields and much narrower PDI. We also investigated the spontaneous copolymerization of 4-VP activated with various protic acids in the reaction with various electron rich comonomers. However, generally protic salt forms showed less solubility in organic solvents and showed low molecular weight polymer products with low yields. The proposed initiation mechanism exhibits the formation of a σ-bond between the β-carbons of the two donor-acceptor monomers, creating the 1,4-tetramethylene biradical intermediate initiating the copolymerization. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1709–1716, 1999
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