Funian Mo,Jianfeng Ban,Lulu Pan,Bo Shi,Shaorong Lu
In this study, a novel series of supramolecular liquid crystalline (LC) polyurethane composites, named SMPU–#HOBA (# represents the molar ratio of HOBA/BINA), were successfully prepared by incorporating hexadecyloxybenzoic acid (HOBA) into pyridine-containing polyurethane (PU). The effect of HOBA on the structure, morphology, and properties has been carefully investigated. The results demonstrate that the obtained SMPU–#HOBA composites not only maintained the LC property of the HOBA mesogen, but also enhanced the intrinsic crystallization of the soft segment phase. Thus, the composites showed an excellent multi-shape memory property with two crystalline temperatures. Moreover, self-gripping was demonstrated revealing reversible bidirectional shape memory by virtue of molecular flipping and movement of the hard segment domain. These composites display a rare combination of LC properties, multi-shape memory properties, and reversible bidirectional shape memory properties, which makes them ideal for many potential applications in smart temperature sensitive devices.
A new tetranuclear Zn(II) complex, [{Zn(L)(μ-OAc)Zn(H 2 O)} 2 ], based on an asymmetrical salamo-type bisoxime chelating ligand H 3 L (6-hydroxy-4′-chloro-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol) was synthesized and characterized by elemental analyses, differential thermal methods, single-crystal X-ray crystallography, and IR, UV–vis, and fluorescence spectra. The Zn(II) complex crystallizes in the triclinic system, space group P -1 with cell parameters a = 9.0742(6) Å, b = 11.8225(5) Å, c = 12.4182(8) Å, Z = 2, V = 1212.56(12) Å 3 , R 1 = 0.0572, and wR 2 = 0.1734. The environment of the tetranuclear Zn(II) complex is penta-coordinated having a slightly distorted trigonal bipyramidal geometry. Moreover, a 1D chain supramolecular structure is formed along the c -axis by the intermolecular C1–H1B⋯O14 hydrogen bonds; in the same manner, C2–H2C⋯Cg2 functions in the formation of supramolecular structures along the a -axis of the 1D chain. A 2D supramolecular structure along the ac plane extends infinitely under the force of intermolecular hydrogen bonds. Differential scanning calorimetry-thermogravimetry thermal analysis provides evidence of the coordination of Zn(II) atoms to the ligand H 3 L. The Zn(II) complex shows intense photoluminescence with a maximum emission at ~453 nm upon excitation at 360 nm.
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