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Polymers 2010, 2(4), 623-648; doi:10.3390/polym2040623

Photo-Induced Micellization of Block Copolymers

1,*  and 2
Received: 30 September 2010 / Revised: 16 November 2010 / Accepted: 25 November 2010 / Published: 26 November 2010
(This article belongs to the Special Issue Advanced Polymer Architectures)
Download PDF [448 KB, uploaded 26 November 2010]
Abstract: We found novel photo-induced micellizations through photolysis, photoelectron transfer, and photo-Claisen rearrangement. The photolysis-induced micellization was attained using poly(4-tert-butoxystyrene)-block-polystyrene diblock copolymer (PBSt-b-PSt). BSt-b-PSt showed no self-assembly in dichloromethane and existed as isolated copolymers. Dynamic light scattering demonstrated that the copolymer produced spherical micelles in this solvent due to irradiation with a high-pressure mercury lamp in the presence of photo-acid generators, such as bis(alkylphenyl)iodonium hexafluorophosphate, diphenyliodonium hexafluorophosphate, and triphenylsulfonium triflate. The 1H NMR analysis confirmed that PBSt-b-PSt was converted into poly(4-vinylphenol)-block-PSt by the irradiation, resulting in self-assembly into micelles. The irradiation in the presence of the photo-acid generator also induced the micellization of poly(4-pyridinemethoxymethylstyrene)-block-polystyrene diblock copolymer (PPySt-b-PSt). Micellization occurred by electron transfer from the pyridine to the photo-acid generator in their excited states and provided monodispersed spherical micelles with cores of PPySt blocks. Further, the photo-Claisen rearrangement caused the micellization of poly(4-allyloxystyrene)-block-polystyrene diblock copolymer (PASt-b-PSt). Micellization was promoted in cyclohexane at room temperature without a catalyst. During micellization, the elimination of the allyl groups competitively occurred along with the photorearrangement of the 4-allyloxystyrene units into the 3-allyl-4-hydroxystyrene units.
Keywords: micellization; photolysis; photoelectron transfer; photo-claisen rearrangement; self-assembly; micelles; photo-acid generators; block copolymers micellization; photolysis; photoelectron transfer; photo-claisen rearrangement; self-assembly; micelles; photo-acid generators; block copolymers
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Yoshida, E.; Kuwayama, S. Photo-Induced Micellization of Block Copolymers. Polymers 2010, 2, 623-648.

AMA Style

Yoshida E, Kuwayama S. Photo-Induced Micellization of Block Copolymers. Polymers. 2010; 2(4):623-648.

Chicago/Turabian Style

Yoshida, Eri; Kuwayama, Satoshi. 2010. "Photo-Induced Micellization of Block Copolymers." Polymers 2, no. 4: 623-648.

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