Colloid

Emulsion

Phase (matter)

Polyethylene glycol

Engineering

Nanoparticle

Nanocellulose

Materials science

Chromatography

Cellulose

PEG ratio

Economics

Chemical engineering

Polymer

Nanotechnology

Organic chemistry

Aqueous solution

Composite material

Chemistry

Finance

Liquid crystal

Dextran

Optoelectronics

ACS Nano

We report on the formation of water-in-water liquid crystal emulsions with permeable colloidal assemblies. Rodlike cellulose nanocrystals (CNC) spontaneously self-assemble into a helical arrangement with the coexistence of nonionic, hydrophilic polyethylene glycol (PEG) and dextran, whereas the two polymer solutions are thermodynamically incompatible. Stable water-in-water emulsions are easily prepared by mixing the respective CNC/polymer solutions, showing micrometric CNC/PEG dispersed droplets and a continuous CNC/dextran phase. With time, the resulting emulsion demixes into an upper, droplet-lean isotropic phase and a bottom, droplet-rich cholesteric phase. Owing to the osmotic pressure gradient between PEG and dextran phases, target transfer of cellulose nanoparticles occurs across the water/water interface to reassemble into a liquid crystal-in-liquid crystal emulsion with global cholesteric organization. The observed structural, optical, and temporal evolution confirm that the colloidal particles in the two immiscible phases experience short-range interactions and form long-range assemblies across the interface.

All-Aqueous Liquid Crystal Nanocellulose Emulsions with Permeable Interfacial Assembly