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Synthesis of ultra‐high molecular weight polyacrylonitrile with highly isotactic content ( mm > 0.60) using dialkylmagnesium/polyhydric alcohol system as catalyst
Author(s) -
Nakano Yasuhiro,
Hisatani Kunio,
Kamide Kenji
Publication year - 1995
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/pi.1995.210360112
Subject(s) - tacticity , polymerization , alicyclic compound , polyacrylonitrile , polymer chemistry , catalysis , anisole , viscometer , molar mass distribution , polymer , triad (sociology) , materials science , monomer , intrinsic viscosity , chemistry , organic chemistry , viscosity , psychology , composite material , psychoanalysis
An attempt was made to synthesize a catalyst having high activity for synthesis of highly isotactic polyacrylonitrile (PAN) with high molecular weight by anionic polymerization. The reaction products of di‐ n ‐hexylmagnesium [( n ‐C 6 H 13 ) 2 Mg] with alicyclic alcohols such as 1,4‐cyclohexanediol or 1,5‐decalindiol were found to be effective as polymerization catalysts for preparation of PAN samples whose triad isotacticity [the content of mm (m , meso configuration)] is about 0.64 and viscosity‐average molecular weight ( M v ) exceeds 1 × 10 5 . The triad tacticities [ mm , mr , and rr contents ( r , racemo configuration)] of the polymers obtained were analysed by 13 C NMR and their M v s were determined by viscometry in dimethylsulphoxide at 25°C using Kamide et al .'s Mark–Houwink–Sakurada equation. M v of PAN increased significantly by after‐treatment of the catalysts, prepared from ( n ‐C 6 H 13 ) 2 Mg and alicyclic alcohols, with triethylalyminium (Et 3 Al). Ultra‐high molecular weight PAN samples ranging in M v from 2 × 10 6 to 6 × 10 6 [( mm ) = 0.57–0.66] were obtained in anisole at 135°C by using the above catalyst system. A main role of Et 3 Al in these catalyst systems is considered to reduce, in advance, OH groups on the catalyst, resulting in a significant suppression of termination reactions of propagating PAN chains during the polymerization.