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UV Resin Enhanced Stability of Metal Halide Perovskite Nanocrystals for White Light-Emitting Diodes
摘要： The long-term stability issue of metal halide perovskite nanocrystals (NCs) is one of the challenges for the applications in optoelectronic devices. Herein, we demonstrate the enhanced air, moisture, and light stability of these NCs by encapsulation into UV Resin (UVR). As prepared perovskite NCs-UVR composites exhibit well maintained optical properties. In addition, the composites show excellent stability with almost identical luminescent behavior for more than 60 days upon continuous exposure in air, moisture, light irradiation, which is superior to the other previous reports. Moreover, we have used these green- and red-emitting composite sheets to fabricate white light-emitting diodes (LEDs) by stacking them on top of the blue LED. We observed a bright neutral white light with a correlated color temperature of 5623 K, a color-rendering index of 85, and a high luminous efficacy of radiation (~349 lm/W). Our findings show the great potential of employing this technique for diverse photonic applications.
关键词： halide perovskites,UV resin,air and moisture stability,white light-emitting diodes,polymerization
更新于2025-09-12 10:27:22
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Femtosecond laser fabrication of 3D templates for mass production of artificial compound eyes
摘要： Compound eyes are unique optical imaging systems that consist of numerous separate light-sensitive units (ommatidia). Attempts have been made to produce artificial compound eyes via advanced 3D nanotechnologies. Among them, femtosecond laser direct writing (FsLDW) technology has emerged as an effective strategy due to its distinct advantages in 3D designable and high precision fabrication capability. However, the point-by-point scanning process results in a very low fabrication efficiency, limiting the practical applications of the FsLDW technology. To solve this problem, we propose a high-efficiency method for the mass production of 3D artificial compound eyes using a photopolymer template fabricated by FsLDW. The resultant 3D SU-8 compound eye templates could be used to replicate polydimethylsiloxane (PDMS) compound eyes many times (over 50 times) with a highly improved efficiency (nearly 20 times higher than the efficiency of direct fabrication using the point-by-point FsLDW). The PDMS replicas showed good focusing and imaging performances. We anticipate that this method may serve as an enabler for the mass production of 3D artificial compound eyes and promote their practical applications in the near future.
关键词： Two-photon polymerization,Compound eyes,PDMS casting,Femtosecond laser
更新于2025-09-12 10:27:22
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A Facile Photocontrolled Iodine‐Mediated Reversible‐Deactivation Radical Polymerization System: Solution Polymerization of Methacrylates under Irradiation with NIR LED Light
摘要： Herein, near-infrared (NIR) photocontrolled iodine-mediated reversible-deactivation radical polymerization (RDRP) of various methacrylates without external photocatalyst was developed using alkyl iodide (e.g., 2-iodo-2-methylpropionitrile, CP-I) as the initiator at room temperature. We report the first example of using a series of special solvents containing carbonyl groups (e.g., 1,3-dimethyl-2-imidazolidinone (DMI), N,N-dimethylacetamide (DMAc), tetramethylurea (TMU), 1,3-dimethyl-tetrahydropyrimidin-2(1H)-one (DMPU), and N-methyl pyrrolidone (NMP)) as both solvent and catalyst for photocontrolled RDRP under irradiation with a long wavelength (λmax = 730 nm) light-emitting diode (LED) light. Therefore, the NIR photocontrolled polymerization system has the simplest components: monomer, alkyl iodide initiator and solvent. Well-defined polymers were synthesized with excellent control over the molecular weights and molecular weight distributions (Mw/Mn < 1.21). The “living” features of this promising NIR photocontrolled iodine-mediated RDRP system were confirmed by polymerization kinetics, multiple controlled “on-off” light switching cycle regulation, and chain extension experiments. Importantly, the radical polymerizations were also proceeded successfully with various thickness of skin of pork and A4 paper to demonstrate the unique advantages of this simplest polymerization system, which benefitting from the high penetration of NIR light.
关键词： radical polymerization,photopolymerization,alkyl iodide,NIR light,photocatalyst-free
更新于2025-09-12 10:27:22
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A Facile Photocontrolled Iodine-Mediated Reversible-Deactivation Radical Polymerization System: Solution Polymerization of Methacrylates under Irradiation with NIR LED Light
摘要： Herein, near-infrared (NIR) photocontrolled iodine-mediated reversible-deactivation radical polymerization (RDRP) of various methacrylates without external photocatalyst was developed using alkyl iodide (e.g., 2-iodo-2-methylpropionitrile, CP-I) as the initiator at room temperature. We report the first example of using a series of special solvents containing carbonyl groups (e.g., 1,3-dimethyl-2-imidazolidinone (DMI), N,N-dimethylacetamide (DMAc), tetramethylurea (TMU), 1,3-dimethyl-tetrahydropyrimidin-2(1H)-one (DMPU), and N-methyl pyrrolidone (NMP)) as both solvent and catalyst for photocontrolled RDRP under irradiation with a long wavelength (λmax = 730 nm) light-emitting diode (LED) light. Therefore, the NIR photocontrolled polymerization system has the simplest components: monomer, alkyl iodide initiator and solvent. Well-defined polymers were synthesized with excellent control over the molecular weights and molecular weight distributions (Mw/Mn < 1.21). The “living” features of this promising NIR photocontrolled iodine-mediated RDRP system were confirmed by polymerization kinetics, multiple controlled “on-off” light switching cycle regulation, and chain extension experiments. Importantly, the radical polymerization were also proceeded successfully with various thickness of skin of pork and A4 paper to demonstrate the unique advantages of this simplest polymerization system, which benefitting from the high penetration of NIR light.
关键词： radical polymerization,photopolymerization,alkyl iodide,NIR light,photocatalyst-free
更新于2025-09-12 10:27:22
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Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron–Electron Resonance
摘要： Synthetic polymers are mixtures of chains with different lengths, and their chain length and chain conformation is often experimentally characterized by ensemble averages. We demonstrate that Double-Electron-Electron-Resonance (DEER) spectroscopy can reveal the chain length distribution, and chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura Coupling Polymerization (cSMCP). The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation and flexibility can also be accessed within poly(fluorene) nanoparticles.
关键词： controlled polymerization,polymer particles,wormlike chain model,conjugated polymers,Electron paramagnetic resonance,double-Electron-Electron resonance (DEER),distance determination
更新于2025-09-12 10:27:22
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Propagation Kinetics of Isoprene Radical Homopolymerization Derived from Pulsed Laser Initiated Polymerizations
摘要： The propagation kinetics of isoprene radical polymerizations in bulk and in solution are investigated via pulsed laser initiated polymerizations and subsequent polymer analyses via size-exclusion chromatography, the PLP-SEC method. Because of low polymerization rate and high volatility of isoprene, the polymerizations are carried out at elevated pressure ranging from 134 to 1320 bar. The temperatures are varied between 55 and 105 °C. PLP-SEC yields activation parameters of kp (Arrhenius parameters and activation volume) over a wide temperature and pressure range that allow for the calculation of kp at technically relevant ambient pressure conditions. The kp values determined are very low, e.g., 99 L mol?1 s?1 at 50 °C, which is even lower than the corresponding value for styrene polymerizations. The presence of a polar solvent results in a slight increase of kp compared to the bulk system. The kp values reported are important for determining rate coefficients of other elemental reactions from coupled parameters as well as for modeling isoprene free-radical polymerizations and reversible deactivation radical polymerization with respect to tailored polymer properties and optimizing the polymerization processes.
关键词： polyisoprene,radical polymerization,kinetics,pulsed laser initiated polymerization
更新于2025-09-11 14:15:04
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Radical induced cationic frontal twin polymerization of Si-spiro compound in combination with bisphenol-A-diglycidylether
摘要： The radical induced cationic frontal polymerization (RICFP) of the twin monomer with 2,2’-spirobi[4H-1,3,2-benzodioxasiline] combination (SPIRO) in bisphenol-A-diglycidylether (BADGE) has been developed to fabricate nanostructured hybrid material with domain sizes of 2–5 nm. In one reaction step, an interpenetrating network of phenolic resin, SiO2 and the epoxy resin is formed in a very short time period, initiated by UV light. That indicates that both polymerization reactions take place simultaneously. The influence of monomer composition on molecular structure was investigated by means of solid state NMR spectroscopies. The envisaged nanostructure of the resulting organic-inorganic hybrid materials is proven by transmission electron microscopy high-angle annular dark-field scanning (HAADF-STEM). The thermal properties of the hybrid materials are comparable to “state of the art” materials with the advantage that the silica quantity can be adjusted on demand.
关键词： Nanostructured hybrid material,HAADF-STEM,Solid state NMR spectroscopy,Radical induced cationic frontal polymerization,Twin polymerization
更新于2025-09-11 14:15:04
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Fabrication of Large Single Crystals for Pt‐Based Linear Polymers with Controlled‐Release and Photoactuator Performance
摘要： Preparation of large single crystals for linear polymers that are amenable to X-ray analysis is very challenging in polymer science. Herein, we employed a coordination driven self-assembly strategy to secure appropriate head-to-tail alignment of anthracene moieties, and for the first time obtained large-sized Pt-based linear polymer crystals through a [4+4] cycloaddition of anthracene in a single-crystal fashion. Using X-ray diffraction analysis to precisely determine polymer crystal structure, we revealed that both the polymerisation and depolymerisation steps proceed via a stable intermediate. Taking advantage of the temperature-dependent slow depolymerization, the afforded Pt-based linear polymer showed potential as a sustained release anticancer drug platform. Furthermore, utilizing the reversible contraction effect of unit-cell volume upon irradiation or heating, the stimuli-responsive crystals were hybridized with polyvinylidene fluoride to obtain a ‘smart material’ with outstanding photoactuator performance. This work not only provides a new approach to prepare metal-containing linear polymer crystals, but also broadens their potential applications towards drug controlled-release and actuator functions.
关键词： Sustained release,Polymer crystals,Linear polymer,Topochemical polymerization,Actuator
更新于2025-09-11 14:15:04
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Crosslinkable Bis(diphenylamine)‐Substituted Mixed Dihydroindeno[1,2‐b]fluorenes for Solution‐Processed, Multilayer OLEDs
摘要： The synthesis and application of a series of crosslinkable bis(diphenylamine)-substituted mixed dihydroindeno[1,2-b]fluorenes as model systems for the fabrication of solution-processed, multilayer OLEDs is described. Introducing a novel functionalization approach by C(sp3)-C(sp2) Suzuki-Miyaura reactions, the synthesis is based on a modular strategy, leading to eight nearly isoelectronic derivatives which allow for the observation of structure-property-relationships in the context of crosslinkable hole-transport materials, e.g. for use in organic light-emitting diodes (OLEDs). By systematically altering structural parameters, such as the number of crosslinkable oxetane moieties per molecule (2-6 moieties) and their position of attachment (geminal and/or lateral), process relevant thermal properties such as thermal stability and glass-transition temperature can be influenced and allow for the investigation of their impact on the crosslinking behavior and the resulting device performance.
关键词： polymerization,materials science,crosslinking,oxetane,OLED
更新于2025-09-11 14:15:04
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Synthesis of molecular‐weight‐controlled polyfluorene with boronate at one end
摘要： We investigated the synthesis of poly?uorene with a pinacol boronate (PinB) moiety at one end and with controlled molecular weight by means of Suzuki–Miyaura coupling polymerization of 7-bromo-9,9-dioctyl-9H-?uoren-2-yl boronate (1) with a palladium(0) precatalyst in the presence of pinacol 4-tri?uoromethylphenylboronate (2) as a chain terminator and CsF/18-crown-6 as a base. When we used AmPhos Pd G2, which has a propensity for intramolecular catalyst transfer on a π-electron face, poly?uorene with the PinB moiety at one end and PhCF3 (derived from 2) at the other end was obtained, and the molecular weight increased in proportion to the feed ratio of [1]0/[catalyst]0, though the molecular weight distribution was broad. Since the molecular weight also linearly increased with respect to the conversion of 1 until the middle stage of polymerization, the polymerization appears to involve chain-growth polymerization through intramolecular catalyst transfer from the Pd catalyst inserted into the C Br bond of 1. The broad molecular weight distribution might be mainly due to slow initiation and slow termination with 2, rather than polymer–polymer coupling.
关键词： polymer end,conjugated polymer,Suzuki polycondensation,palladium catalyst,poly?uorene,catalyst-transfer condensation polymerization
更新于2025-09-11 14:15:04