Transfer of Chirality from Molecule to Phase in Self-Assembled Chiral Block Copolymers

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• 作者：Rong-Ming Ho ; Ming-Chia Li ; Shih-Chieh Lin ; Hsiao-Fang Wang ; Yu-Der Lee ; Hirokazu Hasegawa ; Edwin L. Thomas
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：July 4, 2012
• 年：2012
• 卷：134
• 期：26
• 页码：10974-10986
• 全文大小：774K
• 年卷期：v.134,no.26(July 4, 2012)
• ISSN：1520-5126

文摘

Here, we report the mechanisms of chiral transfer at various length scales in the self-assembly of enantiomeric chiral block copolymers (BCPs*). We show the evolution of homochirality from molecular chirality into phase chirality in the self-assembly of the BCPs*. The chirality of the molecule in the BCP* is identified from circular dichroism (CD) spectra, while the handedness of the helical conformation in the BCP* is determined from a split-type Cotton effect in vibrational circular dichroism spectra. Microphase separation of the BCP* is exploited to form a helical (H*) phase, and the handedness of helical nanostructure in the BCP* is directly visualized from transmission electron microscopy tomography. As examined by CD and fluorescence experiments, significant induced CD signals and a bathochromic shift of fluorescence emission for the achiral perylene moiety as a chemical junction of the BCPs* can be found while the concentration of the BCPs* in toluene solution is higher than the critical micelle concentration, suggesting a twisting and shifting mechanism initiating from the microphase-separated interface of the BCPs* leading to formation of the H* phase from self-assembly.