Supramolecular assembly of helical homopolymers to form stable chiral entities in water is highly valuable for creating chiral nanostructures and fabricating chiral biomaterials. Here we report on thermally induced supramolecular assembly of helical dendronized poly(phenylacetylene)s (PPAs) in aqueous solutions, and their in-situ photo-crosslinking at elevated temperatures to afford crosslinked nano-assemblies with hierarchical structures and stabilized helicities. These helical dendronized homopolymers carry cinnamate-cored dendritic oligoethylene glycol (OEG) pendants, which exhibit characteristic thermoresponsive behavior. Their thermal aggregation confers hexagonal packing of the polymer chains, and simultaneously resulting in enhancement of their chiralities. Assisted by radial amphiphilicity and worm-like molecular geometry, these dendronized PPAs form supramolecular twisted fibers, spheroid particles or toroids via thermal aggregation. Through UV photoirradiation above their cloud points (Tcps), cycloaddition of cinnamate moieties from the dendritic pendants promotes intermolecular crosslinking of dendronized PPA chains within the thermal aggregates, and simultaneously, the dynamic morphologies and supramolecular chirality from the dendronized PPAs through thermally induced aggregation can be fixed. In addition, photo-crosslinking can be occurred solely within individual aggregates due to the protection of densely packed dendritic OEGs. Therefore, various crosslinked assemblies from the dendronized homopolymers with tailorable morphologies and stabilized chirality are fabricated by tuning their thermally induced dynamic aggregations followed by in-situ photo-crosslinking. We believe that this work paves a convenient route to fabricate chiral assemblies with stabilized morphologies and fixed chiralities from dynamic helical homopolymers through intermolecular crosslinking, which can be promising for various chiral applications.

A stimuli-responsive multiple chirality switching material, which can regulate opposed chiral absorption characteristics, has great application value in the fields of optical modulation, information storage and encryption, etc. However, due to the rareness of effective functional systems and the complexity of material structures, developing this type of material remains an insurmountable challenge. Herein, a smart polymer film with multiple chirality inversion properties was fabricated efficiently based on a newly-designed acid & base-sensitive dye-grafted helical polymer. Benefited from the cooperative effects of various weak interactions (hydrogen bonds, electrostatic interaction, etc.) under the aggregated state, this polymer film exhibited a promising acid & base-driven multiple chirality inversion property containing record switchable chiral states (up to five while the solution showed three-state switching) and good reversibility. The creative exploration of such a multiple chirality switching material can not only promote the application progress of current chiroptical regulation technology, but also provide a significant guidance for the design and synthesis of future smart chiroptical switching materials and devices.

Polymerized high internal phase emulsions (polyHIPEs) with circularly polarized luminescence (CPL), as an interesting class of porous materials, are of great significance for the development of CPL porous materials but have not been reported so far. Herein, we report the construction of polyHIPE-based CPL porous materials, taking advantage of an adsorption strategy. The pristine polyHIPEs constructed by chiral helical polymers, which acted as a chiral microenvironment, were fabricated by coordination polymerization of chiral acetylene monomers (R/S-SA) using HIPEs as templates. Achiral fluorescent small molecules were dispersed in the pores of the 3D porous organic chiral polymer matrix provided by polyHIPEs through the adsorption strategy, and CPL-active porous materials with blue, cyan, and green emissions were constructed using a fluorescence-selective absorption mechanism that does not rely on chirality transfer at the molecular level. The maximum luminescence dissymmetry factor (glum) value was -2.6 × 10-2. This work establishes a new and simple way for developing CPL porous materials.

Precise control over the chirality and morphologies of polymer assemblies, a remaining challenge for both chemists and materials scientists, is receiving ever-increasing attention in the recent years. Herein, we report the subtle manipulation of the achiral spacers from the chiral stereocenter to the azobenzene (Azo) unit, of which the chiroptical consistency or chiroptical inversion of self-assemblies could be successfully controlled and present \"two-fold\" odd-even effect. Furthermore, morphological transitions from 0D spherical micelles, 1D worms, and nanowires to 3D vesicles, spindle- and dumbbell-shaped vesicles were also unexpectedly found to exhibit odd-even correlations. These observations were collectively elucidated by mesomorphic properties, stacking modes, chiroptical dynamics, and stimuli-responsive behaviors. Negligible modifications to the spacer structures can enable remarkable modulation of supramolecular chirality and anisotropic topologies in polymer assemblies, which is of great significance for the design of complex chiral functional polymers.

This review mainly highlights our studies on the synthesis of one-handed helical polymers with a static memory of helicity based on the noncovalent helicity induction with a helical-sense bias and subsequent memory of the helicity approach that we developed during the past decade. Apart from the previous approaches, an excess one-handed helical conformation, once induced by nonracemic molecules, is immediately retained (\"memorized\") after the complete removal of the nonracemic molecules, accompanied by a significant amplification of the asymmetry, providing novel switchable chiral materials for chromatographic enantioseparation and asymmetric catalysis as well as a highly sensitive colorimetric and fluorescence chiral sensor. A conceptually new one-handed helix formation in a racemic helical polymer composed of racemic repeating units through the deracemization of the pendants is described.

Flexible nonvolatile memristors have potential applications in wearable devices. In this work, a helical polymer, poly (N, N-diphenylanline isocyanide) (PPIC), was synthesized as the active layer, and flexible electronic devices with an Al/PPIC/ITO architecture were prepared on a polyethylene terephthalate (PET) substrate. The device showed typical nonvolatile rewritable memristor characteristics. The high-molecular-weight helical structure stabilized the active layer under different bending degrees, bending times, and number of bending cycles. The memristor was further employed to simulate the information transmission capability of neural fibers, providing new perspectives for the development of flexible wearable memristors and biomimetic neural synapses. This demonstration highlights the promising possibilities for the advancement of artificial intelligence skin and intelligent flexible robots in the future.

Developing high performance and environment-friendly fluoropolymers is greatly desired. In this work, we found that 2-diazo-1,1,1-trifluoroethane can be polymerized by air-stable alkyne-palladium(II) catalysts following a living polymerization mechanism, affording a fluoropolymer, poly(trifluoromethyl methylene) in high yield with controlled molar mass and low dispersity. This polymer bears trifluoromethyl on every main chain atom and thus has good resistance to chemical corrosion, high hydrophobicity, and excellent dielectric constant with low dielectric loss. Due to the steric hindrance between the trifluoromethyl pendants, the synthetic poly(trifluoromethyl methylene) can twist into a stable helix. The one-handed preferred helices synthesized using chiral PdII -catalysts exhibit high optical activity and circularly polarized luminescence. Remarkably, such polymer can be completely degraded to (E)-1,1,1,4,4,4-hexafluorobut-2-ene at high temperatures (>280 °C). Additionally, taking advantage of the living chain end, the polymer can be further modified.

Preparation of chiral materials from achiral helical polymers has aroused great interest among researchers. In this work, chiral small molecules were utilized to accomplish chiral induction toward racemic helical polyacetylene via intermolecular π-π stacking by which chiral films with strong optical activity were fabricated. Furthermore, introducing fluorescent components generated full-color and white circularly polarized luminescence (CPL). A CPL generation mechanism is proposed accordingly, namely circularly polarized light excitation (CP-Ex). CPL emission and amplification of the luminescence dissymmetry factor were achieved under the synergetic effect of CP-Ex and chirality transfer. The CP-Ex mechanism was further verified by the double-layered film consisting of a chiral layer and a fluorescent layer. More noticeably, for double-layered films, the sense of CPL signals can be switched by changing the direction of excitation light. This work opens up new strategies for exploring tunable multiple- and white-color CPL materials.

Two-dimensional (2D) chiral materials have been attracting immense attentions owing to their unique properties. Herein, we successfully developed a unique assembly strategy of amphiphilic homopolymers to construct stable free-standing 2D chiral nanosheets in solution. The amphiphilic poly(phenylacetylene) (PPA) homopolymers bearing the hydrophobic and hydrophilic dendritic side chains adopt a DNA-like double-helical conformation. The regular hexagonal nanosheets were formed in THF/EtOH through nucleation and epitaxial growth. The sizes of the nanosheets can be modulated from nanometers to submillimeters upon varying the ratio of binary solvents, while the thickness is linearly correlated with the molecular weights. The 2D architecture can significantly enhance the CPL of polymers with a high dissymmetry factor ≈0.1. Driven by a discrimination of helical conformation, the PPAs can self-sort into homochiral 2D nanosheets, as directly visualized by using fluorescent microscopy.

The [N···I···N]+ type halogen bond has been utilized to synthesize supramolecular architectures, while the applications in constructing helical motifs and modulating supramolecular chirality have been unexplored so far. In this work, the [N···I···N]+ halogen bond was introduced to drive the formation of supramolecular helical polymers via a Ag(I) coordination intermediate, showing tunable supramolecular chirality. Pyridine segments were conjugated to the asymmetric ferrocene skeleton, which show \"open\" and \"closed\" geometry depending on the sp2 N positions. Coordination with Ag(I) generated one-dimensional (1D) double helices and 2D helicates featured the [Ag(O)···I···Ag(O)]+ bond, which further stacked into 3D porous frameworks with chiral channels and adjustable pore sizes. Ionic exchange afforded 1D supramolecular helical polymers in solution phases driven by the [N···I···N]+ type halogen bonds, which was evidenced by the experimental results and density functional theory calculation. Fc2 exclusively demonstrated tunable supramolecular chirality in the formation of coordinated and halogen bonded polymers. In addition, solvent change would further inverse the helicity of halogen bonded supramolecular helical polymers depending on the rotation of the ferrocenyl core whose \"closed\" and \"open\" states were accompanied by the breakage of intramolecular hydrogen bonds. This work introduces a [N···I···N]+ type ionic halogen bond to prepare supramolecular helical polymers, providing multiple protocols in regulating helicity by ion exchange and solvent environments.