All-Aqueous Liquid Crystal Nanocellulose Emulsions with Permeable Interfacial Assembly

Area of Science:

• Materials Science
• Colloid and Surface Chemistry
• Soft Matter Physics

Background:

• Cellulose nanocrystals (CNC) exhibit liquid crystalline properties.
• Nonionic polymers like polyethylene glycol (PEG) and dextran are thermodynamically incompatible in aqueous solutions.
• Water-in-water (W/W) emulsions are challenging to stabilize due to interfacial tension.

Purpose of the Study:

• To investigate the formation and evolution of W/W liquid crystal emulsions stabilized by CNC.
• To explore the self-assembly behavior of CNC across immiscible polymer phases.
• To characterize the structural and optical properties of the resulting liquid crystal-in-liquid crystal emulsions.

Main Methods:

• Preparation of W/W emulsions by mixing CNC/PEG and CNC/dextran solutions.
• Observation of emulsion demixing into isotropic and cholesteric phases.
• Analysis of colloidal particle transfer and reassembly across the W/W interface using structural and optical methods.

Main Results:

• Stable W/W emulsions with CNC/PEG droplets in a CNC/dextran continuous phase were formed.
• Emulsions demixed over time into distinct isotropic and cholesteric liquid crystal phases.
• Cellulose nanoparticles transferred across the interface, leading to a global cholesteric organization in the final liquid crystal-in-liquid crystal emulsion.

Conclusions:

• Permeable colloidal assemblies of CNC can stabilize W/W emulsions.
• Osmotic pressure drives CNC transfer and self-assembly across the W/W interface.
• This study demonstrates a novel route to create complex liquid crystal-in-liquid crystal hierarchical structures.