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Butyllithium‐initiated anionic synthesis of well‐defined poly(styrene‐ block ‐ethylene oxide) block copolymers with potassium salt additives
Author(s) -
Quirk Roderic P.,
Kim Jungahn,
Kausch Charles,
Chun Moonseok
Publication year - 1996
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199601)39:1<3::aid-pi436>3.0.co;2-o
Subject(s) - ethylene oxide , copolymer , styrene , polymer chemistry , potassium , anionic addition polymerization , alkoxide , polymerization , oxide , ethylene , materials science , butyllithium , lithium (medication) , chemistry , organic chemistry , polymer , catalysis , medicine , endocrinology
Poly(styrene‐ block ‐ethylene oxide) (PS–PEO) diblock copolymers have been synthesized with predictable block molecular weights and narrow molecular weight distributions. sec ‐Butyllithium‐initiated polymerization of styrene was effected in benzene solution followed by ω‐end‐group functionalization with ethylene oxide to form the corresponding polymeric lithium alkoxide (PSOLi). Block copolymerization of ethylene oxide initiated by the unreactive PSOLi was promoted by addition of dimethylsulfoxide and either potassium t ‐butoxide, potassium t ‐amyloxide or potassium 2,6‐di‐ t ‐butylphenoxide. Although the PS–PEO block copolymer product contained some poly(ethylene oxide) homopolymer, the poly(ethylene oxide) block M̄ n was in good agreement with the calculated value and the molecular weight distribution of the final block was generally narrow ( M̄ w / M̄ n ≤ 1.1). The amount of PEO homopolymer was minimized using potassium 2,6‐di‐ t ‐butylphenoxide rather than potassium t ‐alkoxides.