Chiro-optical Materials Based on a Racemic Polymer

Intense circular dichroism (CD) phenomena, both in the ultraviolet and infrared spectral regions, are produced in syndiotactic polystyrene (s-PS) amorphous samples, when their crystallization is induced by volatile nonracemic molecules, leading to the formation of cocrystalline phases between the racemic polymer host and the nonracemic guest. These CD phenomena remain essentially unaltered also after complete removal of the nonracemic guest as well as after thermal treatments up to 240 °C, i.e., below the s-PS melting temperature. Hence, the described crystallization procedures, as induced by temporary sorption of nonracemic guests, provide an easy way to produce stable chiro-optical materials of any thickness and shape.