Influence of Methylene Blue on Optical and Thermal Properties of Dye-Doped Hydrogen-Bonded Liquid Crystal Mixture

Dye-doped hydrogen-bonded liquid crystals (HBLC) have been prepared using the ultrasonication method and are characterized to explore the optical and thermal properties. Polarizing optical microscopic (POM) analysis reveals the thermochromic effect in nematogen and smectogen of the mixtures. Thermal properties such as LC transition temperature, entropy, enthalpy, order transition, thermic stability, and phase width are analyzed using differential scanning calorimetric (DSC) studies. The noteworthy observation of (RGBY) color changes in nematogen and smectogen are observed in the Methylene Blue (MB) doped mesogens. It is noticed that the bandgap energy ( E g ) value decreases substantially in the dye-doped HBLC mixture when compared to dye-doped LC. In addition to that quenching of different smectic phases into a single smectic C phase in the dye-doped HBLC is also reported. It is important to notice that the MB doped 4-dodecyloxy benzoic acid (12OBA) and diglycolic acid (DGA) comprised HBLC mixture exhibit thermochromic effect with extended mesophase width.