Preparation of micrometer-sized, onionlike multilayered block copolymer particles by two-step AGET ATRP in aqueous dispersed systems: effect of the second-step polymerization temperature.
The polymerization rate, control/livingness, and particle morphology in seeded activators generated by electron transfer for the atom-transfer radical polymerization of styrene with PiBMA-Br macroinitiator particles were investigated at 70, 90, and 110 degrees C. At 110 degrees C, the polymerization proceeded quickly until 60% conversion was reached, but control/livingness was not observed. This seems to be the reason for the high activation rate and spontaneous initiation of styrene, which significantly increased the radical concentration, resulting in a number of radical terminations. As a result, the block copolymer was not sufficiently formed, leading to a sea-island structure. However, at 70 and 90 degrees C, the polymerizations were almost complete in 14 and 7 h, respectively. Control/livingness was maintained, resulting in PiBMA-b-PS. As a result, onionlike multilayered particles were successfully synthesized. These polymerization behaviors were discussed from the viewpoint of the radical concentration and propagation rate coefficient at various temperatures.
Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan.
Yukiya
Y
Kitayama
Yasuyuki
Y
Kagawa
Hideto
H
Minami
Masayoshi
M
Okubo
D007700:Kinetics; D008689:Methacrylates / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D011137:Polystyrenes / Q000138:chemical synthesis* / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry
D008689:Methacrylates; D011137:Polystyrenes; C551283:poly(isobutyl methacrylate)-b-polystyrene; D014867:Water