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.
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.
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DOI：
10.1021/la904296h
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
Yukiya Kitayama;Y. Kagawa;H. Minami;M. Okubo
中科院分区：
文献类型：
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作者：
Yukiya Kitayama;Y. Kagawa;H. Minami;M. Okubo
在70、90和110 ℃下研究了苯乙烯与PiBMA-Br大分子引发剂颗粒的原子转移自由基聚合中由电子转移产生的种子活化剂的聚合速率、控制/活性和颗粒形态。在110摄氏度下，聚合反应迅速进行，直到达到60%的转化率，但没有观察到控制/活性。这似乎是苯乙烯的高活化速率和自发引发的原因，这显著增加了自由基浓度，导致许多自由基终止。结果，嵌段共聚物没有充分形成，导致海岛结构。然而，在70和90 ° C下，聚合分别在14和7小时内几乎完成。维持控制/活性，产生PiBMA-b-PS。结果，洋葱状多层粒子被成功地合成。从不同温度下自由基浓度和增长速率系数的角度讨论了这些聚合行为。
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.