Polymers 2015, 7(6), 1177-1191; doi:10.3390/polym7061177
Size-Controlled Nanomicelles of Poly(lactic acid)–Poly(ethylene glycol) Copolymers with a Multiblock Configuration
1
Department of Biomedical Engineering, National Cerebral and Cardiovascular Center Research Institute Fujishiro-dai, Suita, Osaka 565-8565, Japan
2
Department of Biobased Materials Science, Kyoto Institute of Technology Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
*
Author to whom correspondence should be addressed.
Academic Editor: Alexander Böker
Received: 13 March 2015 / Revised: 9 June 2015 / Accepted: 18 June 2015 / Published: 23 June 2015
Abstract
The ability to control the micelle size of poly(lactic acid) and poly(ethylene glycol) (PLA–PEG) block copolymers is important for controlling their circulation in blood cell recognition, drug release and therapeutic effects. We successfully controlled the micelle size by changing the block number of copolymers (multiblock index). PLA–PEG multiblock copolymers with multiblock indexes ranging from 1.35 to 2.78 were synthesized by direct polycondensation with tin chloride/p-toluenesulfonic acid binary catalysts, using PEG with a molecular weight (Mw) of 3200 Da. The Mw of PLA–PEG copolymers increased with an increase in the multiblock index, while micelle size, measured by dynamic light scattering, decreased greatly from 349 to 28 nm. In addition, the X-ray diffraction peak of the PLA crystal disappeared when the multiblock index was increased. These results indicate that a multiblock structure is useful for controlling micelle size without changing the PLA/PEG composition or PEG molecular weight, which strongly influences other micelle features. View Full-Text
Figure 1
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Somekawa, S.; Masutani, K.; Hsu, Y.-I.; Mahara, A.; Kimura, Y.; Yamaoka, T. Size-Controlled Nanomicelles of Poly(lactic acid)–Poly(ethylene glycol) Copolymers with a Multiblock Configuration. Polymers 2015, 7, 1177-1191.
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