Tunable Thermotropic Liquid Crystals Using Amphiphilic Sequence-Defined Macromolecules

Area of Science:

• Materials Science
• Polymer Chemistry
• Supramolecular Chemistry

Background:

• Polymeric liquid crystals (LCs) are vital for advanced technologies but often lack molecular precision.
• This limitation hinders systematic control over their phase behavior and material properties.

Purpose of the Study:

• To develop a modular synthetic strategy for creating sequence-defined amphiphilic columnar liquid crystals.
• To investigate how molecular structure, including hydrophobic core topology and polar oligomer characteristics, influences LC phase behavior.

Main Methods:

• Utilized a thiolactone-based iterative protocol for sequence-defined polar oligomer synthesis.
• Prepared amphiphilic columnar liquid crystals with varying hydrophobic di- and trialkylated galloyl cores and polar oligomer lengths/types.
• Employed differential scanning calorimetry, polarized optical microscopy, and X-ray scattering for characterization.

Main Results:

• The number of hydrophobic C18 chains on the core is the primary determinant of mesophase stability.
• Tri-C18 chain derivatives showed higher transition temperatures and more distinct lamellar-to-columnar phase transitions than di-C18 analogues.
• Polar block chemistry and length fine-tuned crystallization and mesophase behavior, with hydrogen-bonding heads enhancing stability and bulkier heads reducing crystallinity.

Conclusions:

• Liquid crystalline behavior can be precisely encoded at the molecular level through rational design.
• This approach enables the development of novel responsive and sequence-programmed liquid crystal materials.