TEMPO-controlled radical suspension polymerization of poly(styrene)-block-poly(styrene-co-acrylonitrile) and poly(styrene)-block-poly(styrene-co-butylmethacrylate)
C. Taube et G. Schmidt-naake, TEMPO-controlled radical suspension polymerization of poly(styrene)-block-poly(styrene-co-acrylonitrile) and poly(styrene)-block-poly(styrene-co-butylmethacrylate), MACRO MAT E, 279(6), 2000, pp. 26-33
Suspension polymerization expands the study of controlled radical polymeriz
ation to high conversions and is known as a method to synthesize polymers w
ith high molecular weights. The radical block copolymerizations of styrene
(S) and acrylonitrile (AN) or butyl methacrylate (BUMA) controlled by 2,2,6
,6-tetramethylpiperidine-N-oxyl (TEMPO) was performed in an oil/water press
ure reactor system at a temperature of 125 degrees C. TEMPO-terminated styr
ene homopolymer was employed as macroinitiator. The systems were examined b
y varying the composition of the monomer mixture at a constant reaction tim
e, as well as by varying the reaction time for a characteristic monomer com
position to get all of the possible conversion range. The solubility effect
s of acrylonitrile in the suspension medium were considered, Furthermore, t
he yield of the reaction was improved through initiator addition by taking
control of the reaction. The polymerizations could proceed under control up
to a conversion of 80-90%. By using the copolymerization equations, the so
lubility of pure acrylonitrile in the suspension medium could be calculated
and was found to be 8 wt.%.