Dominant Factors Affecting Rheological Properties of Cellulose Derivatives Forming Thermotropic Cholesteric Liquid...

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials

Background:

• Thermotropic cholesteric liquid crystals (CLCs) typically require complex synthesis from petroleum-based chiral and mesogenic compounds.
• Hydroxypropyl cellulose (HPC) derivatives offer a sustainable alternative, being readily prepared from biomass resources.
• These HPC derivatives possess alkanoyl side chains and form CLCs with visible light reflection.

Purpose of the Study:

• To investigate the linear rheological behavior of thermotropic CLCs based on HPC derivatives with varying alkanoyl side chain lengths.
• To understand the relationship between CLC helical structures and rheological properties.
• To explore fabrication strategies for oriented CLC helices using shearing force for eco-friendly photonic devices.

Main Methods:

• Synthesis of HPC derivatives via complete esterification of hydroxy groups.
• Rheological measurements to determine linear viscoelastic properties.
• Analysis of master curves and relaxation peaks to infer helical axis motion.
• Investigation of shearing force effects on CLC helix orientation.

Main Results:

• Master curves of HPC derivatives were nearly identical at reference temperatures, reflecting light at 405 nm.
• Relaxation peaks around ~10^2 rad/s indicated CLC helical axis motion.
• Rheological properties were strongly dependent on the CLC helical structures.
• Shearing force demonstrated potential for fabricating highly oriented CLC helices.

Conclusions:

• HPC derivatives provide a viable, eco-friendly route to CLCs with tunable properties.
• Rheological behavior is intrinsically linked to the CLC helical structure.
• Shearing force is a promising method for creating oriented CLC structures for advanced photonic applications.