ABA block copolymers without tapering by isokinetic living anionic polymerization in a series of stirred tank reactors
作者:
D. Hesterwerth,
F. Bandermann,
期刊:
Die Angewandte Makromolekulare Chemie
(WILEY Available online 1991)
卷期:
Volume 184,
issue 1
页码: 111-121
ISSN:0003-3146
年代: 1991
DOI:10.1002/apmc.1991.051840110
出版商: Hüthig&Wepf Verlag
数据来源: WILEY
摘要:
AbstractEquations for the molecular weight distribution and the average molecular weights of a living anionic polymerization with very rapid or slow initiation are presented for a series of stirred tank reactors. It is shown that polydispersity of the polymer in the last vessel of a cascade takes for nearly complete conversion of monomer then a minimum, when the reaction is performed isokinetically with concern to monomer conversion, i.e. when monomer conversion in each vessel of a cascade of n tanks is 1/n. Now, polydispersity of the polymer in the mth vessel of the cascade (1 ≤ m ≤ n) is Dm= 1 + 1/m. Values of all systems variables needed for isokinetic control of the polymerization may be precalculated from kinetic models. For vessels of equal size and with equal residence times reaction temperature is suggested as control variable increasing stepwise from vessel to vessel. The proposed procedure was checked for the systems styrene/n‐butyllithium/toluene, styrene/s‐butyllithium/benzene, and isoprene/s‐butyllithium/n‐heptane. A satisfying agreement between calculated and measured values of the objectives monomers conversion, number average molecular weight, and polydispersity was found. It is proposed to use the described procedure for the preparation of ABA block copolymers with negligible tapering between the blocks by living anionic polymerization in a series of stirred ta
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