Search

Circularly polarized organic room temperature phosphorescence (CPRTP) with gmax = +0.098 was activated by the rigid environment of an in situ cross-linked liquid crystalline polymer network.

Traditional luminescent liquid crystals (LLCs) suffer from fluorescence quenching caused by aggregation, which greatly limits their further application. In this work, a kind of novel LLCs (named carbonized polymer dot liquid crystals (CPD-LCs)) are designed and successfully synthesized through grafting the rod-shaped liquid crystal (LC) molecules of 4'-cyano-4-(4″-bromohexyloxy) biphenyl on the surface of CPDs. The peripheral LC molecules not only increase the distance between different CPDs to prevent them from aggregating and reduce intermolecular energy resonance transfer but also make this LLC have an ordered arrangement. Thus, the obtained CPD-LCs show good LC property and excellent high luminous efficiency with an absolute photoluminescence quantum yield of 14.52% in the aggregated state. Furthermore, this kind of CPD-LC is used to fabricate linearly polarized devices. The resultant linearly polarized dichroic ratio (N) and polarization ratio (ρ) are 2.59 and 0.44, respectively. Clearly, this type of CPD-LC shows promising applications for optical devices.

Circularly polarized luminescent materials play an increasingly important role in display equipment and optical apparatuses. Herein, we design and synthesize a kind of luminescent liquid crystallin...

Luminescent materials with stimuli-responsive behavior have good prospects for application in displays, sensors, and other fields. In this research, a type of luminescent supramolecular polymer was fabricated, via hydrogen bonding, that shows stimuli-responsive behavior with different types of acid. Firstly, the acceptor material luminogen (4,4′-dibutanoxy tetraphenylethylene)-1-pyridine (PTPEC4) is synthesized. Then, the PTPEC4 is used to prepare luminescent supramolecular polymer PVA(PTPEC4)x by complexing the donor material poly(vinyl alcohol) (PVA) with different amounts of PTPEC4. The PVA(PTPEC4)x exhibits a lamellar structure at x ≥ 0.6, whereas a crystalline structure forms with x ≤ 0.4. Because of the protonation effect of the pyridine group in PTPEC4, PVA(PTPEC4)x not only exhibits solid-state emission behavior but also presents multicolor luminescence switching under different acid vapors. Moreover, because of the existence of the hydrogen bonds, PVA(PTPEC4)1.0 shows a reversible, spontaneous fluorescence switch under acid vapor with a pKa > 5.25. If the sample is fumed with acid vapor with pKa < 5.25, PVA(PTPEC4)1.0 only exhibits a larger luminescence red shift but cannot recover unless the sample is treated with triethylamine vapor. Furthermore, a rewritable paper with tunable multicolor emission and high contrast is prepared based on the fluorescence response and recovery behavior, which may be applied in optical memory systems.

To explore the optoelectronic properties of liquid crystalline polymers (LCPs), two luminescent liquid crystalline polymers (LLCPs) with high-efficiency emission in the solid state, namely poly([3-(4′,4′′-dibutyloxy)tetraphenylethylene]styrene) (PSTPE) and poly(3,5-bis[(4′,4′′-dibutyloxy)tetraphenylethylene]styrene) (PS2TPE), on the basis of aggregation-induced emission (AIE) and a “jacketing” effect, are successfully prepared through radical polymerization under mild conditions. The chemical structures of the monomers and polymers are identified via nuclear magnetic resonance (NMR), MALDI-TOF MS and gel permeation chromatography (GPC) characterization. AIE and aggregation-enhanced emission (AEE) behavior are shown by the resulting LLCPs PSTPE and P2STPE, respectively. Meanwhile, the results of wide-angle X-ray diffraction (WAXD) analysis reveal that the LLCPs can form typical smectic phases. More interestingly, both polymers show higher emissive efficiency after thermal annealing. Further, the results of WAXD and ultraviolet-visible (UV-vis) studies indicate that the polymers can form more ordered structures, which means that an increase in ordering can enhance emission.

A series of high efficiency luminescent liquid crystalline polymers (LLCPs) based on aggregation-induced emission (AIE) and the “Jacketing” effect, namely, poly{2,5-bis{[2-(4-oxytetraphenylethylene)-n-alkyl]oxycarbonyl}styrene} (denoted as Pm, m = 2, 4, 6, 8, 10, 12), were successfully designed and synthesized via introducing tetraphenylethylene to the side group with different length spacers. Because of the AIE effect, the resultant LLCPs are completely free of aggregation caused quenching. The photophysical properties and phase behavior were studied via various techniques such as UV–vis absorption spectra, photoluminescence spectra (PL), polarized light microscopy (PLM), differential scanning calorimetry (DSC), and variable temperature one-dimensional wide-angle X-ray diffraction (1D WAXD). The results revealed that the resultant monomers showed typical AIE behavior and the polymers exhibited aggregation enhanced emission (AEE) behavior. Moreover, due to the “Jacketing” effect, the polymers showed high ...

Phase-transition and orientation of liquid crystal (LC) are two crucial factors for LC application. In this work, a long rod-like LC compound containing double azobenzene (M1) is successfully designed and synthesized. The combing technologies of nuclear magnetic resonance (1H NMR, 13C NMR) and Fourier transform infrared spectroscopy (FTIR) are used to identify the chemical structure of the molecule. Additionally, the polarized optical microscopy (POM), differential scanning calorimetry (DSC), and one-dimensional wide-angle X-ray diffraction (1D WAXD) experimental results show that M1 exhibits an ultrawide range of LC phases and a stable LC structure even at ultrahigh temperature, which indicates that this LC can be applied in some especial devices. Further, the compound M1 is used to tune the LC temperature range of the commercial LC 4-cyano-4′-pentylbiphenyl (5CB). A series of samples 1–7 are obtained through doping different contents of M1, which show different LC temperature ranges that are dependent on the composition ratio of M1 and 5CB. More interestingly, all resultant samples show spontaneous vertical orientation on the hydrophilic glass substrate. Meanwhile, due to the effect of azobenzene in the compound M1, a reversible transition between homeotropic to random orientation of the LC molecules is achieved when these LC cells are alternately exposed to UV irradiation and visible light, which implies that this material shows potential application in especial display and optical storage technologies.