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Homochiral Evolution in Self-Assembled Chiral Polymers and Block Copolymers
Tao Wen1, Hsiao-Fang Wang1, Ming-Chia Li2
1Department of Chemical Engineering, National Tsing Hua University , Hsinchu 30013, Taiwan.
Accounts of Chemical Research
|March 4, 2017
Summary
Researchers examined chirality transfer in self-assembling chiral polymers and block copolymers. They found evidence of homochiral evolution across molecular, conformational, and hierarchical scales using advanced spectroscopic and imaging techniques.
Area of Science:
- Supramolecular Chemistry
- Polymer Science
- Chirality Studies
Background:
- Chirality transfer is fundamental to biological systems and synthetic materials.
- Understanding self-assembly mechanisms is crucial for controlling hierarchical chirality.
- Chiral bias transfer from molecular to hierarchical levels remains a key challenge.
Purpose of the Study:
- To summarize methodologies for examining homochiral evolution in self-assembled chiral polymers and block copolymers.
- To investigate chirality transfer across molecular, conformational, and hierarchical scales.
- To demonstrate the attainability of homochiral evolution in self-assembly processes.
Main Methods:
- Synthesis of enantiomeric polystyrene-b-poly(lactide) block copolymers (PS-PLLA and PS-PDLA).
- Characterization using electronic circular dichroism (ECD) for molecular chirality.
- Vibrational circular dichroism (VCD) for conformational chirality.
- 3D transmission electron microscopy (3D TEM) for hierarchical chirality and helical nanostructures.
- Polarized light microscopy (PLM) for handedness determination in crystallized chiral polylactides.
Main Results:
- Discovery of a helical (H*) phase in block copolymer self-assembly due to chirality.
- Confirmation of homochiral evolution in self-assembled block copolymers via ECD, VCD, and 3D TEM.
- Observation of twisted lamellae in crystallized chiral polylactides, with determined handedness.
- Evidence suggests homochiral evolution in both self-assembled block copolymers and crystallized chiral homopolymers.
Conclusions:
- Significant progress in spectral and morphological determination of chirality at multiple length scales.
- Methodologies presented provide insights into chirality transfer mechanisms in self-assembly.
- Homochiral evolution is attainable in self-assembly of chiral polymers and block copolymers, offering pathways to understand natural homochirality.
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