Ultraviolet light screen using cholesteric liquid crystal capsules on the basis of selective reflection

Area of Science:

• Materials Science
• Nanotechnology
• Photoprotection

Background:

• Sunscreen protects skin from UV radiation, specifically UV-A and UV-B.
• Developing advanced UV-filtering systems is crucial for effective sun protection.

Purpose of the Study:

• To propose and investigate a new UV screen system utilizing cholesteric liquid crystals (CLC).
• To achieve selective UV-A light reflection within the physiological temperature range of human skin (32-36 °C).

Main Methods:

• Fabrication of polycaprolactone (PCL) microcapsules containing a CLC mixture via solvent evaporation.
• Characterization of CLC/PCL microcapsules with an average diameter of approximately 34 μm.
• Evaluation of UV-A light reflection properties of the CLC mixture and microcapsules within the target temperature range.

Main Results:

• The CLC mixture (COC:CN = 80:20) demonstrated selective reflection of UV-A light (350-380 nm) at human skin temperatures.
• The developed CLC/PCL microcapsules effectively blocked a broad spectrum of UV light (290-400 nm) by approximately 6%.

Conclusions:

• Cholesteric liquid crystal microcapsules offer a promising approach for temperature-dependent UV-A light filtering.
• This technology has potential applications in advanced sunscreen formulations for enhanced photoprotection.