ISSN:
0959-8103
Keywords:
stereospecific polymerization
;
polyacrylonitrile
;
tacticity
;
anionic polymerization
;
dialkylmagnesium
;
polyhydric alcohol
;
ultra-high molecular weight
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
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-C6H13)2Mg] 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 (Mv) exceeds 1 × 105. The triad tacticities [mm, mr, and rr contents (r, racemo configuration)] of the polymers obtained were analysed by 13C NMR and their Mvs were determined by viscometry in dimethylsulphoxide at 25°C using Kamide et al.'s Mark-Houwink-Sakurada equation.Mv of PAN increased significantly by after-treatment of the catalysts, prepared from (n-C6H13)2Mg and alicyclic alcohols, with triethylalyminium (Et3Al). Ultra-high molecular weight PAN samples ranging in Mv from 2 × 106 to 6 × 106 [(mm) = 0.57-0.66] were obtained in anisole at 135°C by using the above catalyst system. A main role of Et3Al 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.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pi.1995.210360112
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