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In the 21st century, soft materials will become more important as functional materials because of their dynamic nature. Although soft materials are not as highly durable as hard materials, such as metals, ceramics, and engineering plastics, they can respond well to stimuli and the environment. The introduction of order into soft materials induces new dynamic functions. Liquid crystals are ordered soft materials consisting of self-organized molecules and can potentially be used as new functional materials for electron, ion, or molecular transporting, sensory, catalytic, optical, and bio-active materials. For this functionalization, unconventional materials design is required. Herein, we describe new approaches to the functionalization of liquid crystals and show how the design of liquid crystals formed by supramolecular assembly and nano-segregation leads to the formation of a variety of new self-organized functional materials.

The mollusk shell is a hard tissue consisting of calcium carbonate crystals and an organic matrix. The nacre of the shell is characterized by a stacked compartment structure with a uniformly oriented c axis of aragonite crystals in each compartment. Using a calcium carbonate-binding assay, we identified an acidic matrix protein, Pif, in the pearl oyster Pinctada fucata that specifically binds to aragonite crystals. The Pif complementary DNA (cDNA) encoded a precursor protein, which was posttranslationally cleaved to produce Pif 97 and Pif 80. The results from immunolocalization, a knockdown experiment that used RNA interference, and in vitro calcium carbonate crystallization studies strongly indicate that Pif regulates nacre formation.

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Altering the shape and properties of a material through external factors such as heat, light, pressure, pH, electric or magnetic fields, or the introduction of a guest molecule, is an attractive prospect. In this Perspective, piezochromic luminescent materials - which change the colour of their luminescence in response to mechanical stimuli - are described. Such piezochromism has been observed for a few molecular materials that contain luminescent cores in liquid-crystalline and crystalline solid states, as well as for polymeric materials doped with dyes. These changes in photoluminescent colour can be activated by various types of mechanical pressure such as shearing, grinding or elongation, which can trigger different mechanisms of producing the colour. Such stimuli-responsive materials have potential for various applications, including sensors, memory and displays.