The transformation of chiral signals into macroscopic properties of materials using chirality-responsive polymers

The ability to transform the chiral signals of molecules into the macroscopic properties of a material will offer significant advantages in the development of chiral functional devices and chirality-related applications. Chirality-responsive polymers provide an excellent platform to realize this objective, which often involves two basic strategies. The first strategy is to utilize various external stimuli to directly mediate the chiral conformations of a polymer, through which the energy input is transformed into a macroscopic change in the properties of a material. The second strategy is to utilize the enantioselective interaction between polymers and guest chiral molecules to trigger a stepwise conformational change in smart polymers, which then results in transformation of the macroscopic properties. This review summarizes recent progress in generating chirality-responsive polymers based on these strategies and discusses advances in their applications as chiral sensors, liquid crystals, optical and electrical devices, nanomachines and so on. We then introduce the emerging field of chiral bio-interface materials, in which chiral signals are transformed into changes in the macroscopic behavior of cells and biomacromolecules based on the stereo-specific interactions between biological systems and artificial materials. Chirality – the ‘handedness’ of entities whose mirror images of each other are not superimposable, such as our left and right hands, or helices that twist in opposite directions – is a crucial concept in chemistry and biology: changing the handedness of chiral molecules has a profound impact on their properties. Guangyan Qing and Taolei Sun review how chiral-responsive polymers can convey a signal from the molecular to the macroscopic level. Two strategies can be adopted: incorporating chiral units into the structure of stimuli-responsive polymers, or altering interactions between polymers and chiral molecules. Specific triggers, such as chemical or thermal signals, alter the chirality of these systems, which in turn affect their macromolecular and materials properties. This can be exploited to construct functional devices, such as for sensing or electronic applications, and to control the conformation of inherently chiral biosystems. Life is a multiscale chiral system, which ingeneously combine small chiral biomolecules to biomacromolecules with special stereo-conformations and functions via chemical bonding and weak chemical interactions, for example, hydrogen bonding and hydrophobic interactions, which further assemble to build up macroscopic biological entities showing distinct assymetric characteristics, for example, right-handed conches and so on. This brings much inspiration to construct artificial systems being able to transform chiral signals to macroscopic properties of materials based on chirality-responsive polymers, which find broad applications in various domains of chemical engineering, industry, biology and medicine.