期刊
ULTRASONICS SONOCHEMISTRY
卷 15, 期 3, 页码 222-226出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.ultsonch.2007.03.010
关键词
ultrasonic irradiation; emulsion polymerization; alcohol; hydroxyl radical scavenger
Ultrasonically initiated emulsion polymerization of styrene was carried out in the presence of aliphatic alcohols, e.g. methanol, ethanol, n-pronanol and n-butanol, as volatile hydroxyl radical scavengers. With the addition of methanol, the polymerization rate of styrene increased, while the molecular weight and the average particle size of the produced polystyrene decreased because more radicals were produced in the presence of methanol. This is true also for the other polymerization system using other aliphatic alcohols, such as ethanol, n-pronanol and n-butanol, suggesting that the alcohols enter into cavitation bubbles and further react with hydroxyl radicals ((OH)-O-center dot) from the sonolysis of water to produce hydroxyalkyl radicals, so as to reduce the recombination of H-center dot and (OH)-O-center dot radicals, therefore more radicals will be present in the systems for initiating polymerization. Obviously, it is an effective way to enhance ultrasonically initiated emulsion polymerization rate of styrene by adding volatile hydroxyl radical scavenger. (c) 2007 Elsevier B.V. All rights reserved.
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