SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3992-y
Two-dimensional (2D) materials exhibit excellent electrical, optical, and mechanical properties, yet precise control over chiral 2D materials remains a significant challenge. This work introduces asymmetric side chain engineering to prepare helically grooved poly(3,5-disubstituted phenylacetylene)s (PPAs) and investigates the effect of their asymmetric contour on tailoring 2D nanostructures. Post-polymerization modification of a common platform polymer efficiently produced a series of rigid helical PPAs with varying alkyl side chain lengths while maintaining identical degrees of polymerization and distribution. Increasing side chain asymmetry yielded anisotropic hexagonal platelets with progressively higher aspect ratios, whereas symmetric side chains formed regular 2D hexagonal sheets. Notably, the largest side chain asymmetry generated supramolecular structures with distinct chiral vortices. Computational simulations elucidated different self-assembly mechanisms, revealing that vortex-like assemblies are kinetically stabilized rather than thermodynamically stable. All 2D assemblies exhibited significantly enhanced circularly polarized luminescence (CPL) compared to discrete polymer solutions, with dissymmetry factors (g_lum) reaching as high as 0.1. This work establishes side chain asymmetry as a crucial factor for programming supramolecular chirality and opens new avenues for developing advanced chiroptical materials.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4042-6
Biopolymers such as proteins exhibit both stability and dynamic properties, reflected in precise conformational adaptability and reversibility within cells. Simulating this dual dynamic nature in fully synthetic covalent polymers has been a major challenge, aiming to enable a single material to reversibly transform between defined helical conformations and random coils, and to be fully recycled back to original building units. Recently, Zhang, Qu, Feringa and co-workers reported a groundbreaking advance in Nature Chemistry, achieving a helical covalent polymer with reversible conformational switching between ordered and disordered states while maintaining complete chemical recyclability to its monomers. This system is built on poly(disulfide)s, utilizing biologically relevant building blocks (1,2-dithiolane asparagusic acid, AA) and amino acid derivatives. Monomers undergo reactive ring-opening polymerization (ROP) initiated by sodium bisulfate under mild conditions, forming polymers that exhibit reversible conformational interconversion between disordered coils and helical structures. Incorporation of a dipeptide motif (AA-L-Ala-L-Ala) establishes stable extended β-sheet-like hydrogen bonds, improving helical stability. Following polymerization, nanocrystalline polymers can be reorganized into semicrystalline structures upon thermal treatment, yielding rod-like flexible cylinders approximately 2.1 nm in diameter and 25 nm in length. Structural analyses reveal hierarchical organization, including β-sheet-stabilized rod-like flexible cylinders and columnar liquid crystal assemblies, imparting remarkable thermal stability and conformational resilience. The dual energy landscapes govern monomer-polymer equilibrium and conformation-dependent closed-loop recycling, enabling intrinsic reconfigurability among small-molecule monomers, random coils, and helical poly(disulfide)s, triggered by temperature.