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Anionic block copolymerization of cyclotetrasiloxanes initiated by p ‐bis(dimethyllithiioxysilyl)benzene
Author(s) -
Liu Zonglin,
Li Yanhui,
Wong Daqin,
Hao Shuxuan
Publication year - 1996
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19961226)62:13<2355::aid-app21>3.0.co;2-0
Subject(s) - copolymer , polymer chemistry , siloxane , polymerization , monomer , molar mass distribution , anionic addition polymerization , chemistry , differential scanning calorimetry , precipitation polymerization , materials science , polymer , radical polymerization , organic chemistry , physics , thermodynamics
The triblock copolymers of poly(diphenyl‐ b ‐dimethyl‐ b ‐diphenyl)siloxane (PMP) and poly(diphenyl‐ b ‐dimethyl‐ co ‐methylvinyl‐ b ‐diphenyl)siloxane (PMVP) have been synthesized by the dianionic polymerization procedure. The polymerization of the cyclotetrasiloxane monomers initiated by lithium‐based initiator has been carried out so as to avoid equilibration reactions. The new initiator, p ‐bis(dimethyllithiioxysilyl)benzene, was used. Dimethyl formamide (DMF) was used as a promotor. The effects of initiator concentration, polymerization temperature, and polymerization time on the reaction were investigated. The block copolymers have been determined by 1 H‐NMR, infrared, ultraviolet, and differential scanning calorimetry. Progressive precipitation separation has been used to study the molecular weight distribution, and the integral distribution curves of the molecular weight have been given. © 1996 John Wiley & Sons, Inc.