Achieving a full color palette with thickness, temperature, and humidity in cholesteric hydroxypropyl cellulose

Hydroxypropyl cellulose (HPC) is a sustainable, cost-efficient, and bio-compatible derivative that forms cholesteric liquid crystalline phases in highlyconcentrated water solutions reflects colour the visible range. While there have been studies exploiting HPC’s structural coloration transferring order of into solid form via cross-linking, still lack understanding on thermotropic mechanisms enable transfer ordering pure HPC at higher temperatures. In this work, we demonstrate balance between temperature, humidity, film thickness to achieve full color palette HPC. We reveal early stages evaporation, formation dense skin over lyotropic phase facilitates thermal expansion during heat treatment. Increasing thickness, applying drying temperatures, exposing samples humidity evaporation all result with increased pitch values cause red-shift state. Our analysis dried controlled temperature conditions fixed provided an dominance which drives final organization phase. When films was varied against conditions, shift from red violet follows gradient sample due change time required reach form.