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Photocatalyzed thiol-alkene coupling: Mechanistic study and polymer synthesis
摘要： Due to the “click” chemistry characteristics of the thiol–ene reaction, these transformations have been gaining an increasing amount of attention in current chemical research. The high efficiency and selectivity of these transformations have been useful for many areas of study, from small molecule organic synthesis, to polymer synthesis and functionalization, to bioconjugation reactions. In this work, a study of a novel method of photochemical thiol–ene reactions using alkyl halides and an tris [2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) photocatalyst is investigated. This process is shown to progress rapidly and has the benefit of low catalyst and initiator concentrations relative to reagents as well as mild conditions associated with photochemical processes. To understand the mechanism of this process, catalyst and initiator concentrations and other reaction conditions are varied. To demonstrate the utility of this process, a step-growth thiol–ene polymer is synthesized using dithiol and diene monomers and a crosslinked polymer network is synthesized as well.
关键词： thiol–ene,radical reactions,step-growth polymerization,polymer network,photochemistry
更新于2025-09-19 17:15:36
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Photo-Cross-Linkable Polymer Inks for Solution-Based OLED Fabrication
摘要： We introduce a catalyst-free, highly e?cient, ambient temperature Diels?Alder reaction employing o-methylbenzaldehyde derivatives as photocaged dienes as an ideal approach for forming three-dimensional insoluble networks for inkjet printing of OLED emissive layer. Herein, poly(methyl methacrylate) based polymers containing 4-(9H-carbazol-9-yl)-2-(3′-hydroxy-[1,1′-biphenyl]-3-yl)isoindoline-1,3-dione as a blue-green (λ max = 495?500 nm) thermally activated delayed ?uorescence (TADF) emitter and a photochemically active maleimide/o-methylbenzaldehyde cross-linker couple were synthesized and their photo-cross-linking behavior was studied. Time resolved ?uorescence measurements con?rm that the TADF properties are maintained upon integration in a polymer network and HOMO/LUMO levels of the emitter species remain unchanged by the photo-cross-linking at 365 nm of the polymer chains. The network formation of the ?uorescent ?lms is evidenced by solvent resistance tests and monitored by Fourier transform infrared (FT-IR) spectroscopy as well as time of ?ight secondary ion mass spectroscopy (ToF-SIMS), showing the consumption of maleimide and o-methylbenzaldehyde groups with increasing irradiation time. The surface roughness is investigated via atomic force microscopy (AFM) and found to be unchanged by a solvent wash after the cross-linking. Furthermore, con?rmation that the polymer solution can be printed on an inkjet-printer and subsequently photo-cross-linked for multilayer OLED device fabrication is obtained.
关键词： photo-cross-linking,TADF emitter,polymer network,Diels?Alder reaction,inkjet printing,OLED
更新于2025-09-12 10:27:22
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Effect of CdSeS/ZnS quantum dot concentration on the electro-optical and dielectric properties of polymer stabilized liquid crystal
摘要： Our research paper has been discussed electro-optical and dielectric characterization of polymer stabilized liquid crystal (PSLC) and its doped form with different concentration of CdSeS/ZnS quantum dot (QD). PSLC composite was prepared using a nematic liquid crystal (E63) and Poly(methyl methacrylate) (PMMA) polymer. In order to improve physical properties, composites were dispersed with different concentration of CdSeS/ZnS QD. The electro-optical and dielectric properties of the composites were investigated depending on the frequency and voltage. Considerable physical parameters such as threshold voltage, dielectric anisotropy, relaxation frequency and response time were obtained from the experimental data. The results show that QD contribution and polymer networks change the electro-optical and dielectric properties of PSLC and these can become a focus of interest for new applications of PSLC composites in the future.
关键词： polymer network,quantum dot,dielectric properties,Polymer stabilized liquid crystal
更新于2025-09-11 14:15:04
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Fast-Tunable Terahertz Metamaterial Absorber Based on Polymer Network Liquid Crystal
摘要： This paper introduces a tunable metamaterial absorber (MA) based on polymer network liquid crystal (PNLC) in the terahertz (THz) frequency band. Under the optimal polymerization condition, through electrical control of the orientation of the PNLC embedded in the frequency selective surface, the resonant frequency of the absorber can be tuned from 416.5 to 405.0 GHz, corresponding to fractional frequency bandwidth of 2.8%. The experimental results show that the proposed MA based on the PNLC offers an adjustment time of 10 ms and recovery time of 85 ms, which is significantly faster than the tunable metamaterial devices based on conventional nematic liquid crystal (LC).
关键词： liquid crystal,response time,absorber,terahertz,polymer network
更新于2025-09-09 09:28:46