The research of RATRP of styrene in the microemulsion

In this paper, the reverse atom transfer radical polymerization of styrene in microemulsion was studied and some small molecular electrolyte was introduced into the microemulsion to limit the content of transition-metal in the aqueous medium by salt effect and to control the molecular weight well ulteriorly. The polymerization was carried out at 80 degrees C, with a mechanical agitator, using 2,2'-A20-bisbutyro-nitrile (AIBN) as initiator and CuCl2/bpy as catalyst, under N-2 atmosphere. Effects of the mole ratio of AIBN/CuCl2/bpy, the kind and content of small molecular electrolyte on the molecular weight of the polymers, and convention of the monomer were investigated through viscosity measurement, gel permeation chromatography, and transmission electronic microscope. The results show that adding CuCl2/bpy to the reactive system could control the increase of the molecular weight and the conversion effectively. The molecular weight and conversion would decrease with the increase of amount of CuCl,. When the mole ratio of AIBN/CuCl2/bpy is 1:2:6, the molecular weight is no more than 18 x 10(4). Adding NaCl or NaBr could make the molecular weight and conversion decrease too. A linear relationship between the molecular weight and the conversion can be obtained when the amount of NaCl or NaBr reaches 1.0% to water. The distribution index of molecular weight of the system with NaCl is narrower than that of system without NaCl. What's more, latex particles' shape is spherical whose diameter is from 10 to 100 nm. All researches we have laid a foundation for further study. (c) 2005 Wiley Periodicals, Inc.