Molecule-based afterglow materials with ultralong-lived excited states have attracted great attention owing to their unique applications in light-emitting devices, information storage, and ...anticounterfeiting. Herein, a series of new types of two-component ionic crystalline materials were fabricated by the self-assembly of cytosine and different anions under ambient conditions. The multiple intermolecular interactions of cytosine with phosphate and halogens anions can lead to abundant energy levels and different crystal stacking modes to control molecular aggregation and excited-state intermolecular proton transfer (ESIPT) process. Interestingly, H-aggregation-induced green to yellow room-temperature phosphorescence (RTP) and ESIPT-dominated cyan RTP to deep blue thermally activated delayed fluorescence (TADF) emission can be generated by tuning excitation wavelength, time evolution, and temperature. Furthermore, the combination of two-component ionic crystals can be used as multicolored candidates for quadruple information encryption. Therefore, this work not only develops an anion-modulated strategy to achieve color-tunable afterglow from both static and dynamic fashions but also provides a guideline for designing forward/reverse excitation-dependent luminescent materials.
Metal–organic hybrids with ultralong room-temperature phosphorescence (RTP) have potential applications in many fields, including optical communications, anticounterfeiting, encryption, bioimaging, ...and so on. Herein, we report two isostructural one-dimensional zinc-organic halides as coordination polymers ZnX2(bpp) (X = Cl, 1; Br, 2; bpp = 1,3-di(4-pyridyl)propane) with excitation wavelength- and time-dependent ultralong RTP properties. The dynamic multicolor afterglow can be assigned to the emission of the pristine ligand bpp and its interactions with halogen atoms. Experiments and theoretical calculations both suggest that ZnX2 is crucial for ultralong RTP: (a) the metal coordination and X...π bonds in coordination polymers fix the bpp molecules and suppress the nonradiative transitions; (b) the spin-orbital coupling of coordination polymers is largely enhanced relative to the bpp because of the heavy atom effect; and (c) the charge transfer exists between halogens and bpp ligand. Therefore, this work not only presents metal-halide coordination polymers with excitation wavelength- and time-dependent RTP properties, but also provides a facile method for the new types of dynamic multicolor afterglow materials.
Uncovering differences between crystalline and amorphous states in molecular solids would both promote the understanding of their structure–property relationships, as well as inform development of ...multi‐functional materials based on the same compound. Herein, for the first time, we report an approach to leverage crystalline and amorphous states of a zero‐dimensional metal‐organic complex, which exhibited negative and positive photochromism, due to the competitive chemical routes between photocycloaddition and photogenerated radicals. Furthermore, different polymorphs lead to the on/off toggling of photo‐burst movement (photosalient effect), indicating the controllable light‐mechanical conversion. Three demos were further constructed to support their application in information encryption and anti‐counterfeiting. This work provides the proof‐of‐concept of a state‐ and polymorph‐dependent photochemical route, paving an effective way for the design of new dynamically responsive systems.
An approach to leverage crystalline and amorphous states of a zero‐dimensional metal‐organic complex in order to tune negative and positive photochromism was proposed, which could be assigned to the competitive chemical routes between photocycloaddition and photogenerated radicals. Furthermore, both polymorphs exhibit mechanochromic photoemission, and lead to the on/off toggling of the light‐driven motion of bulky molecular crystals.
Developing Meta-aramid materials that combine flexibility and strength will greatly expand their application fields. In previous work, it was demonstrated that aromatic ether bonds can contribute to ...improving flexibility. In addition, micro-branched chain structures can reduce intermolecular forces by increasing fractional free volume, while newly formed hydrogen bonding can maintain polymer strength. Therefore, two flexible polymers were obtained by incorporating 4,4′-diaminodiphenyl ether (ODA) and 4,4′-oxybis 3-(trifluoromethyl)benzenamine (OTB) to the molecular chains, respectively, and flexible films were prepared by a combination of solution casting and dry-wet processing methods. By studying the properties of copolymer films with 10% ODA and 10% OTB added, it was found that they can maintain thermal stability and mechanical strength while improving the flexibility of the films. The AFM results visually showed that the DMT modulus of the modified films decreased at the micro level and DMA indicated that the introduction of ODA and OTB can shorten the molecular relaxation time, which reflected the improvement of molecular chain flexibility. Through molecular dynamics simulations, the differences were compared in molecular chain conformation, mean square displacement and hydrogen bonding after the introduction of ODA and OTB and the combined mechanism of aromatic ether bonds and CF3 side groups was confirmed in improving flexibility and maintaining mechanical strength.
Display omitted The combined effect of the hierarchical multiscale of polymers creates their flexibility characteristics.
•Aromatic ether and CF3 structures were introduced into PMIA molecular chain to improve its rigidity and brittleness issues.•The tensile strength and thermal stability of modified PMIA were not damaged, and the elongation at break was improved.•The combined effects of ether bonds and CF3 on hydrogen bonding were investigated through molecular dynamics simulations.•The structure and property relationship of copolymerized PMIA was established.
Basalt fibers (BFs) are eco-friendly and natural high-performance fibers, specifically engineered for use in protective clothing, offering significant benefits. However, the inherent brittleness of ...this inorganic fabric not only poses challenges in processing but also renders it uncomfortable for wear. Consequently, there is an urgent need to modify BFs to enhance their torsional property and skin compatibility. Herein, we immersed BFs in water and twist them into yarn to investigate the effects of water erosion on BFs, specifically focusing on its impact on fiber structure and spinning performance. Under water's erosion, the BFs experienced ion-exchange reactions that compromised the silica framework, leading to a significant rise in both static and dynamic friction coefficients 162.5 % and 233.3 %, respectively, and a 1.53-fold improvement in torsional performance. The process of twisting in a water bath facilitated better fiber bundling, yielding a more compact yarn structure. This compaction reduced the occurrence of burrs following friction and enhanced both tensile and loop strength. At the fiber level, we utilized a simple water erosion method to enhance the twisting performance of basalt filament. This approach circumvents the disadvantages of large etching modification damage and poor sizing fastness, offering a novel method for the preparation of basalt twisted yarn.
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We propose an epoxy molding compound (EMC) encapsulation method based on a metallized reflector to enhance light extraction of deep ultraviolet light-emitting diodes (DUV-LEDs). From the optical ...simulation, the highest light output efficiency of the DUV-LEDs is measured when the angle of the metallied reflector is 35° and the height is 0.5-mm. The optimized EMC structure is fabricated for application to DUV-LEDs packaging. The light output power of the EMC metallized reflector is improved by 14.3% compared to the conventional ceramic package at 20-mA. The thermal resistance of the EMC is 18.16-K/W. Furthermore, after aging tests at 60 °C and 60 °C, 90 %RH for 1000h, the relative light output power of the EMC metallized reflector is decreased by 12% and 14%, respectively.
A reversible CO
2
-responsive luminescent material was constructed by a facile hydrogen-bond self-assembly of a two-component ionic crystal. The modification of CO
2
on the ionic crystal not only ...alternates the green afterglow, but also endows the material with inverse excitation wavelength dependence for multicolor emission.
A hydrogen-bond organized ionic crystal exhibits CO
2
-responsive tunable afterglow.
A reversible CO
-responsive luminescent material was constructed by a facile hydrogen-bond self-assembly of a two-component ionic crystal. The modification of CO
on the ionic crystal not only ...alternates the green afterglow, but also endows the material with inverse excitation wavelength dependence for multicolor emission.
In this work, cationic waterborne polyurethane/acrylate (WPUA) was synthesized for water repellent in cotton fabrics to replace fluorine‐containing finishing agents with the concerns of ecosystems ...and human health. First, the tertiary amines monomers, N‐methyl diethanolamine, 3‐dimethylamine‐1, 2‐propylene glycol, N,N′‐bis (2‐hydroxyethyl)piperazine, were used as chain extenders to prepare waterborne polyurethane, respectively. Long‐chain octadecyl acrylate monomers were then grafted to the waterborne polyurethane by a self‐emulsifying method. The stable WPUA suspensions of positively charged latexes were obtained and could be finished on cotton fabrics via a simple pad‐curing process. The coated cotton fabrics were capable of repelling common liquids without any penetration, and the contact angles of the treated cotton fabrics could reach 150°. The WPUA latex films also exhibited good tensile mechanical properties and thermal dimensional stability. The cotton fabric coated with the WPUA showed good laundering durability, and its static water contact angle was still maintained at 142° even after 50 times washing. This work not only highlights the structural design and preparation but also provides a feasible strategy for fluorine‐free water repellency in cotton fabrics, which has great potential application prospects for a variety of fields.
Strategy for fluorine‐free water repellency in cotton fabrics.
Alternations of crystalline and amorphous states largely influence the solid‐state properties of molecular materials. In their Research Article (e202217054), Dongpeng Yan and co‐workers show that the ...transformation between two states of an anthracene‐based metal‐organic complex can tune the photosalient effect, mechanical luminescence, and photochromism behavior. The effect was assigned to competitive chemical routes between a photocycloaddition reaction in the crystalline state and photogenerated radicals in the amorphous state.
