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.
Kitayama
Yukiya
Y
Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan.
Kagawa
Yasuyuki
Y
Minami
Hideto
H
Okubo
Masayoshi
M
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