Yasuyuki Kagawa

Controlled/Living Radical Polymerization in Dispersed Systems

2.6. Microemulsion Polymerization 3778 2.6.1. General Considerations 3778 2.6.2. Microemulsion NMP 3778 2.6.3. Microemulsion ATRP 3778 2.6.4. Microemulsion RAFT Polymerization 3779 2.6.5. ITP in Microemulsion 3779 2.7. Dispersion and Precipitation Polymerizations 3779 2.7.1. General Considerations 3779 2.7.2. NMP 3780 2.7.3. ATRP 3781 2.7.4. RAFT 3782 2.7.5. Dispersion ITP 3782 3. Cross-linking CLRP in Dispersed Systems 3783 3.1. General Considerations 3783 3.2. Cross-linking NMP 3783 3.3. Cross-linking ATRP 3784 3.4. Cross-Linking RAFT Polymerization 3784 3.5. Cross-Linking ITP 3784 4. Particle Morphology 3785 4.1. General Considerations 3785 4.2. Core-Shell Particles 3785 4.3. Hollow Particles 3785 4.4. Multilayered Particles 3786 5. Conclusions and Outlook 3787 6. List of Abbreviations 3788 7. Acknowledgments 3789 8. References 3789

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.

Dispersion atom transfer radical polymerization of methyl methacrylate with bromo-terminated poly(dimethylsiloxane) in supercritical carbon dioxide

Poly(dimethylsiloxane)-block-poly(methyl methacrylate) particles were successfully prepared by dispersion atom transfer radical polymerization of methyl methacrylate with bromoterminated poly(dimethylsiloxane) as inistab (initiator + stabilizer) in supercritical carbon dioxide medium (scCO2). The block copolymers had narrow molecular weight distributions (M w/M n approx. 1.25), indicating that the polymerization in scCO2 was conducted in a controlled manner.