Liquid-crystal Structure and Theory: the Chimerical Mesophase. towards a New Paradigm Based on Chiral Symmetry Breaking

It is argued that the presumed mesophase theory of liquid crystals, which has evolved over the preceding century and is currently in vogue, is not only largely conjectural but also ignores fundamental theoretical principles and key experimental observations. Essentially, it is unsupported by hard experimental evidence, and the view that a large collection of molecules can remain both ordered and fluid over a wide temperature range can be challenged. Current theory overlooks the apparently unexceptional effects of liquid crystals on polarized light, which indicate the involvement of chirality (cf. the crossed-polarizers experiment). An alternative model proposed herein is based on the idea that chiral symmetry breaking is a fundamental property of matter (deriving from the thermodynamic advantage of the entropy of mixing of a racemate). Thus, even achiral molecules prefer to adopt chiral conformations when possible, which would open a kinetic channel to a non-equilibrium state that is chiral as a whole. This can happen if the racemic mixture of the metastable chiral conformers forms a ‘pseudoconglomerate’, with ‘like’ enantiomers aggregating together. This can ultimately lead to a suspension of chiral nanoparticles in a fluid medium that is possibly also chiral, because of persistent proximity to the nanoparticles. This model of the liquid crystalline state can also explain its amazing electro-optical properties by invoking the development of surface charges on the nanoparticles in an electrical field; this would alter their aggregation behavior, and hence their optical properties. These phenomenal characteristics of matter are apparently manifested under suitable conditions leading to the liquid crystalline state. *E-mail: [email protected]; [email protected]