Poly(L-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture

This paper presents the liquid crystal (LC) properties of poly(L-lactide) (PLLA). Mesophase behavior isinvestigated using polarized opticalmicroscopy, X-ray diffraction, and differential scanning calorimetry. The performedanalyses confirm that pressed PLLAfilms exhibit the unique capability of self-assembling into a nematic mesophase under the influence of mechanical pressure,temperature, and time. It was originally demonstrated that the chiral nematicmesophase can be obtained by introducingfine powders into the polymer. Based onthe research conducted, it was proved that the pressed PLLAfilms have a chiralnematic mesophase with a nematic-to-isotropic phase transition and a largemesophase stability range overlapping the temperature of the human body, whichcan persist for years at ambient temperature. The obtainedfilms show tailor-madeproperties toward a nematic mesophase with a specific texture, including coloredplanar texture of the chiral nematic mesophase and blue-phase (BP) LC texture. TheBP, described for thefirst time in plain PLLA, occurred over a wider than usualtemperature range of stability between isotropic and chiral nematic thermotropic phases (Delta T approximate to 9 degrees C), which is an advantage of theobtained polymer material, in addition to ease of preparation. This opens up new prospects for advanced photonic greenapplications