Title
Transfer of Chirality from Molecule to Phase in Self-Assembled Chiral Block Copolymers
Author
Rong-Ming Ho, Ming-Chia Li, Shih-Chieh Lin, Hsiao-Fang Wang, Yu-Der Lee, Hirokazu Hasegawa, Edwin L. Thomas
Year
2012
Journal
Journal of The American Chemical Society
Abstract
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.
Full Article
Instrument
FVS-6000
Keywords
Vibrational circular dichroism, block copolymers, transfer, molecule