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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. [ABSTRACT FROM AUTHOR]

Yarn tension, predominately determined by the dynamic motion of yarn balloon, is a key factor for spinning speed and yarn qualities, which is attracting an increasing amount of concern in advance spinning field. A novel device called a special-shaped tube (SST) has been introduced in this work, to reduce yarn tension. The SST is installed between yarn guide and traveler to regulate the dynamic balloon, ensuring consecutive yarn spinning with high spindle speed. Theoretical modeling was developed to explain that the SST can lower the yarn tension and reduce the fluctuation of yarn tension by controlling the shape of yarn balloon. Experimental results have confirmed this theoretical analysis. Meanwhile, they also reveal that the SST can be deployed to produce yarns with higher strength than yarns produced with existing balloon control ring (BCR) device. Both yarn hairiness and irregularity are similar for these two types of yarns. This spinning device also helps to isolate yarns from the turbulent flow from both sides, avoiding any negative effect on yarn formation. All superiorities indicate that the SST has the potential to replace balloon separator and BCR in industrial spinning. [ABSTRACT FROM AUTHOR]

We have combined the molecular imprinting and the layer-by-layer assembly techniques to obtain molecularly imprint polymers (MIPs) for the electrochemical determination of p-nitrophenol ( p-NPh). Silica microspheres functionalized with thiol groups and gold nanoparticles (Au-NPs) were assembled on a gold electrode surface layer by layer. The electrode was then immersed into a solution of pyrrole and p-NPh (the template), and electropolymerization led to the creation of a polymer-modified surface. After the removal of the silica spheres and the template, electrochemical impedance spectroscopy and differential pulse voltammetry (DPV) were employed to characterize the surface. The results demonstrated the successful fabrication of macroporous MIPs embedded with Au-NPs on the gold electrode. The effects of monomer concentration and scan rate on the performance of the electrode were optimized. Excellent recognition capacity is found for p-NPh over chemically similar species. The DPV peak current is linearly related to concentration of p-NPh in the 0.1 μM to 1.4 mM range, with a 0.1 μM limit of detection (at S/N = 3). [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]