The current landscape of chiral covalent organic frameworks (COFs) predominantly centered on constructing asymmetric molecular-scale chirality, often introducing an inherent contradiction to the COF symmetry and limiting diversity. Herein, we overcome these challenges by achieving chiral transfer between one-dimensional (1D) imine linear polymers (LPs) and two-dimensional (2D) network β-ketoenamine COFs composed of achiral monomers. We successfully synthesize several 1D imine LPs with mesoscopic helical chirality, comprising achiral C2-symmetric terephthalaldehyde and diamine linkers in a chiral supramolecular transcription system. Leveraging the irreversible tautomerism mechanism within the linker replacement approach, terephthalaldehyde (TPA) units in these helical 1D LPs are substituted with C3-symmetric 1,3,5-triformylphloroglucinol (TP), yielding the corresponding 2D network β-ketoenamine COFs. Crystallinity and helicity of the resultant β-ketoenamine COFs intimately hinge on reaction conditions, including the aldehyde stoichiometry of Tp and TPA, as well as the quantity and concentration of the catalyst employed. Under optimized conditions, the nucleation and growth were precisely governed, achieving a harmonious equilibrium of crystallinity and helicity within the generated 2D network β-ketoenamine COFs, even with covalent bond rupture, recombination, and topological transition (from [C2 + C2] to [C3 + C2]). Impressively, the ground state chirality inherent to helical 1D LPs seamlessly transfers to helical 2D network β-ketoenamine COFs. This study not only offers new perspectives on the development of chiral functional COFs, but also provides fresh insights into the precise control of COFs' microscopic morphology.

Oil pollution is a serious environmental and natural resource problem. Traditional adsorption materials for oil–water separation have limitations in terms of their preparation cost, reusability, and mechanical properties. Among the conventional adsorption materials, super-hydrophobic/super-lipophilic materials are easily contaminated by oil. In this study, polypropylene (PP) is used as a foam substrate to prepare an open-cell PP foam via hot pressing, supercritical CO₂ foaming, and electron beam (EB) irradiation. The impact of EB irradiation dose on the open-cell content of PP foam can lead to cell wall rupture, resulting in an open-cell structure that enhances oil-water separation performance. At an absorbed radiation dose of 200 kGy, the PP foams exhibit optimal oil–water separation performance, cyclic compression stability, heat insulation, and preparation cost. The open-cell content of PP foam is increased to 86.5%, the adsorption capacity for diesel oil is 42.8 g/g, and the adsorption efficiency remains at 99.6% after 100 cycles of oil desorption in a complex pH environment. Meanwhile, cracks and nano-voids simultaneously promote the capillary action of oil, and the oil transport rate is 0.0713 g/(g·s). This study provides a new concept for the preparation of open-cell polymer foams that can meet the demand for high oil-absorption capacity under complex acid-base pH conditions.

As a new favorite in the field of smart materials, smart windows, with visual stimulus sensing functions, have attracted extensive attention for their high transparency, sensitive response to environmental stimulus, and reversible changes in light transmittance. In this paper, the PVA-co-PE nanofiber film, which was completely opaque like paper, was used as filling phase and reacted with water-soluble N-vinyl-2-pyrrolidone (NVP) by photopolymerization to produce a flexible transparency polyvinyl pyrrolidone/ spraying PVA-co-PE nanofiber films (PVP/SPNFs) composite film. Among them, the small size effect of PVA-co-PE nanofibers played a pivotal role in improving the film's transparency. Nevertheless, the PVP's reversible adsorption–desorption behavior of water molecules made its refractive index change dynamically and reversibly, which led to the visual transition of composite film from transparent to opaque just like that of electronic smart windows. Additionally, the reversible transition rate of film's transparency can be effectively regulated by the nanofiber stack structure. This new design of transparency visualization transforms composite film in response to humidity, innovates the electrically controlled smart windows on energy and realizes the effective utilization of natural resources such as water and humidity, which has a great application prospect in the field of flexible optoelectronic devices, intelligent buildings, and smart writing.