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Preparation of ultrahigh molecular weight polyacrylonitrile and its terpolymers
Author(s) -
Zhang C.,
Gilbert R. D.,
Fornes R. E.
Publication year - 1995
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/app.1995.070581119
Subject(s) - acrylonitrile , monomer , polymer chemistry , polyacrylonitrile , molar mass distribution , emulsion polymerization , polymerization , polymer , copolymer , itaconic acid , precipitation polymerization , radical polymerization , chemistry , materials science , chemical engineering , organic chemistry , engineering
The synthesis of high molecular weight (in excess of 10 6 million Daltons) poly(acrylonitrile) and poly(acrylonitrile‐ co ‐methylacrylate‐ co ‐itaconic acid) is described. An inverse emulsion polymerization formulation with AIBN as the initiator was used. However, polymer precipitation occurred early in the polymerization. In each case, the molecular weight distribution was surprisingly narrow (M̄ w /M̄ n ∼ 1.5). Conversion vs. time plots with monomers containing the inhibitor had the “S” shape typical of emulsion polymerizations. The terpolymer composition and molecular weight were quite uniform throughout the polymerization. With inhibitor‐free monomers, the initial molecular weights were very high (∼ 3 × 10 6 Daltons), but gelation occurred at ca. 50% conversion. There was an inverse relationship between the monomer inhibitor content and the polymer molecular weight. It is suggested that the growing polymer radicals are occluded in the precipitated polymer particles and are terminated by inhibitor diffusing into the particles, accounting for the narrow molecular weight distribution. © 1995 John Wiley & Sons, Inc.