scholarly journals Ultraviolet irradiation-responsive dynamic ultralong organic phosphorescence in polymeric systems

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yongfeng Zhang ◽  
Liang Gao ◽  
Xian Zheng ◽  
Zhonghao Wang ◽  
Chaolong Yang ◽  
...  
Keyword(s):  
Ultraviolet Irradiation ◽  
Screen Printing ◽  
Amorphous State ◽  
Poly Vinyl Alcohol ◽  
Ambient Conditions ◽  
Phosphorescence Lifetime ◽  
Polymeric Systems ◽  
Stimulus Responsive ◽  
Irradiation Period ◽  
Organic Phosphors

AbstractRoom temperature phosphorescence (RTP) has drawn extensive attention in recent years. Efficient stimulus-responsive phosphorescent organic materials are attractive, but are extremely rare because of unclear design principles and intrinsically spin-forbidden intersystem crossing. Herein, we present a feasible and facile strategy to achieve ultraviolet irradiation-responsive ultralong RTP (IRRTP) of some simple organic phosphors by doping into amorphous poly(vinyl alcohol) matrix. In addition to the observed green and yellow afterglow emission with distinct irradiation-enhanced phosphorescence, the phosphorescence lifetime can be tuned by varying the irradiation period of 254 nm light. Significantly, the dynamic phosphorescence lifetime could be increased 14.3 folds from 58.03 ms to 828.81 ms in one of the obtained hybrid films after irradiation for 45 min under ambient conditions. As such, the application in polychromatic screen printing and multilevel information encryption is demonstrated. The extraordinary IRRTP in the amorphous state endows these systems with a highly promising potential for smart flexible luminescent materials and sensors with dynamically controlled phosphorescence.

Bioinspired Poly(vinyl alcohol) Film Actuator Powered by Water Evaporation under Ambient Conditions

2020 ◽  
Vol 305 (6) ◽  
pp. 2000145
Author(s):  
Sitong Wang ◽  
Shuang Yan ◽  
Li Zhang ◽  
Huhu Zhao ◽  
Tian Yang ◽  
...  
Keyword(s):  
Vinyl Alcohol ◽  
Water Evaporation ◽  
Poly Vinyl Alcohol ◽  
Ambient Conditions

scholarly journals Cryostructuring of Polymeric Systems. 49. Unexpected “Kosmotropic-Like” Impact of Organic Chaotropes on Freeze–Thaw-Induced Gelation of PVA in DMSO

Gels ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 81 ◽  
Author(s):  
Vladimir Lozinsky ◽  
Olga Kolosova ◽  
Dmitrii Michurov ◽  
Alexander Dubovik ◽  
Viktor Vasil’ev ◽  
...  
Keyword(s):  
Guanidine Hydrochloride ◽  
Aqueous Media ◽  
Poly Vinyl Alcohol ◽  
Gel Formation ◽  
Polymeric Systems ◽  
Freeze Thaw ◽  
Structural Regularity ◽  
Huggins Constant ◽  
Key Factor ◽  
Activation Heat

Urea (URE) and guanidine hydrochloride (GHC) possessing strong chaotropic properties in aqueous media were added to DMSO solutions of poly(vinyl alcohol) (PVA) to be gelled via freeze–thaw processing. Unexpectedly, it turned out that in the case of the PVA cryotropic gel formation in DMSO medium, the URE and GHC additives caused the opposite effects to those observed in water, i.e., the formation of the PVA cryogels (PVACGs) was strengthened rather than inhibited. Our studies of this phenomenon showed that such “kosmotropic-like” effects were more pronounced for the PVACGs that were formed in DMSO in the presence of URE additives, with the effects being concentration-dependent. The additives also caused significant changes in the macroporous morphology of the cryogels; the commonly observed trend was a decrease in the structural regularity of the additive-containing samples compared to the additive-free gel sample. The viscosity measurements revealed consistent changes in the intrinsic viscosity, Huggins constant, and the excess activation heat of the viscosity caused by the additives. The results obtained evidently point to the urea-induced decrease in the solvation ability of DMSO with respect to PVA. As a result, this effect can be the key factor that is responsible for strengthening the structure formation upon the freeze–thaw gelation of this polymer in DMSO additionally containing additives such as urea, which is capable of competing with PVA for the solvent.

scholarly journals Intense greenish phosphorescence emission under ambient conditions in a two-dimensional lead(ii) coordination polymer with a 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate ligand

2017 ◽  
Vol 46 (24) ◽  
pp. 7953-7959 ◽  
Author(s):  
Xiao Liu ◽  
Lu Zhai ◽  
Wen-Wei Zhang ◽  
Jin-Lin Zuo ◽  
Zhu-Xi Yang ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Yield ◽  
Coordination Polymer ◽  
Two Dimensional ◽  
Ambient Conditions ◽  
Phosphorescence Lifetime ◽  
Phosphorescence Emission

A new 2D Pb2+-based coordination polymer emits intense greenish phosphorescence in the solid state under ambient conditions with a quantum yield of 1.5% and a phosphorescence lifetime of 4.17 ms.

Recycling Lignin for Engineering Applications

1992 ◽  
Vol 266 ◽  
Author(s):  
D. Feldman ◽  
D. Banu ◽  
M. Lacasse ◽  
J. Wang
Keyword(s):  
Polymer Networks ◽  
Polymeric Materials ◽  
Interpenetrating Polymer Networks ◽  
Poly Vinyl Alcohol ◽  
Natural Polymer ◽  
Terrestrial Plants ◽  
Polymeric Systems ◽  
Kraft Process ◽  
The Matrix ◽  
Technical Lignins

AbstractLignin, a complex natural polymer produced by all vascular terrestrial plants is second in abundance only to cellulose and is the matrix holding plant fibres together. Lignins are recovered mainly as byproducts from woodpulping processes with about 100 million tons produced annually worldwide.Large volume uses for lignin byproduct other than for generation of energy (kraft process) are most likely to be in materials applications.In the last decades many studies aimed to the recycling of different lignins (sulfite, kraft, organosolv, steam exploded, hydrolytic, etc.) in polymeric systems based on thermoplastics, thermosettings, elastomers, adhesives, sealants, etc.Among all the technical lignins, sulfate lignins are chemically the most reactive and are therefore used to modify polymers. The oldest and the most familiar application of lignin as a component of polymeric materials involves the reinforcement of rubber. Multicomponent materials can be created by combination with other macromolecules like polyethylene, polypropylene, or poly(vinyl alcohol) to produce polyblends, block copolymers or interpenetrating polymer networks.The present communication will try to present such examples of polymeric systems based on recycled lignin, and synthetic polymers such as: polyurethane, epoxy, acrylics, silicones.

scholarly journals Stimulus-responsive liquids for encapsulation storage and controlled release of drugs from nano-shell capsules

2010 ◽  
Vol 8 (56) ◽  
pp. 451-456 ◽  
Author(s):  
Ming-Wei Chang ◽  
Eleanor Stride ◽  
Mohan Edirisinghe
Keyword(s):  
Drug Delivery ◽  
Controlled Release ◽  
Drug Release ◽  
Polymeric Materials ◽  
Controlled Drug Release ◽  
Ambient Conditions ◽  
Smart Polymer ◽  
Release Studies ◽  
Stimulus Responsive ◽  
New Strategy

Drug-delivery systems with a unique capability to respond to a given stimulus can improve therapeutic efficacy. However, development of such systems is currently heavily reliant on responsive polymeric materials and pursuing this singular strategy limits the potential for clinical translation. In this report, with a model system used for drug-release studies, we demonstrate a new strategy: how a temperature-responsive non-toxic, volatile liquid can be encapsulated and stored under ambient conditions and subsequently programmed for controlled drug release without relying on a smart polymer. When the stimulus temperature is reached, controlled encapsulation of different amounts of dye in the capsules is achieved and facilitates subsequent sustained release. With different ratios of the liquid (perfluorohexane): dye in the capsules, enhanced controlled release with real-time response is provided. Hence, our findings offer great potential for drug-delivery applications and provide new generic insights into the development of stimuli drug-release systems.

Carbazole&benzoindole-based purely organic phosphors: a comprehensive phosphorescence mechanism, tunable lifetime and an advanced encryption system

2021 ◽  
Author(s):  
Chen Qian ◽  
Zhimin Ma ◽  
Bingxin Yang ◽  
Xianjiang Li ◽  
Jiayao Sun ◽  
...  
Keyword(s):  
Phosphorescence Lifetime ◽  
Organic Phosphors

The same molecule synthesized from different carbazoles may show various properties, which originate from the trace isomer in purchased carbazole. By changing the content of isomers, the phosphorescence lifetime can be quantitatively adjusted.

C60 Transformations at High Pressures

1992 ◽  
Vol 270 ◽  
Author(s):  
C. S. Yoo ◽  
W. J. Nellis ◽  
M. L. Sattler ◽  
R. G. Musket ◽  
N. Hinsey ◽  
...  
Keyword(s):  
Thin Films ◽  
High Pressure ◽  
Pressure Range ◽  
High Pressures ◽  
Amorphous State ◽  
Ambient Conditions ◽  
Carbon Phase ◽  
Large Pressure ◽  
Diffraction Patterns ◽  
Intermolecular Distances

ABSTRACTC60 molecules have been studied at both shock and static high pressures. Under shock compressions C60 fullerenes are stable into the 13-17 GPa pressure range. The onset of a fast (∼0.5 μs) reconstructive transformation to graphite occurs near 17 GPa. The graphite recovered from 27 GPa and about 900 K is relatively well ordered with La = 100 Å. Above 50 GPa a continuous transformationto an amorphous state is observed in recovered specimens. A transparent, metastable carbon phase was recovered from thin films of C60, shocked to 69 GPa and 2200 K and then rapidly quenched to 1000 K. The selected area diffraction patterns indicate thatthe metastable carbon contains an amorphous diamond and n-diamond. Under hydrostatic compressions C60 molecules transform reversibly to a semi-transparent phase in the pressure range of 15-25 GPa with a large pressure hysteresis. The high pressure phaseconsists of interconnected strongly interacting C60 agglomerates, or networksof fullerenes, whose stability continuously increases with increase of pressure. Above 27 GPa the transition becomes irreversible, and the material recovered from high pressureis metastable and diamond-like at ambient conditions. These pressure-induced transitions are explained in terms of nr-electron rehybridization between C60 molecules, which occurs at substantially decreased intermolecular distances.

scholarly journals Interpenetrating polymeric hydrogels as favorable materials for hygienic applications

2020 ◽  
Vol 10 (2) ◽  
pp. 5011-5020
Keyword(s):  
Biomedical Applications ◽  
Three Dimensional ◽  
Synthetic Polymers ◽  
Poly Vinyl Alcohol ◽  
Ambient Conditions ◽  
Natural Polymers ◽  
Dimensional Network ◽  
Swelling Capacity ◽  
Polymeric Chains ◽  
Poly Ethylene

Polymers can crosslink to produce intermingled materials with three-dimensional network structure known as interpenetrating polymeric network (IPN). They comprise elastic crosslinked polymeric chains. The chains of the hydrogels are either physically or chemically entangled together. Interpenetrating hydrogels can be tailored to provide enhanced materials. They can be classified according to methods of their synthesis as simultaneous or sequential IPNs and the structure to be homo or semi IPNs. The preparation factors play a role in controlling the properties of the produced IPNs. Moreover, the ambient conditions such as pH, temperature as well as the ionic strength may affect the performance of these hydrogels. The swelling capacity is an important feature that allows the prepared hydrogel to perform the required application. Some disadvantages may arise such as the low mechanical properties that are suggested to be overcome. IPNs can be used in various applications that serve the human requirements like drug delivery, tissue engineering, medical and packaging applications. Hydrogels present biocompatibility and nontoxicity when used in biomedical applications. Interpenetrating hydrogels can be prepared from natural or synthetic polymers. Polysaccharides as natural polymers can be used to produce efficient interpenetrating hydrogels. Polyacrylates, poly(ethylene glycol) and poly(vinyl alcohol) are designated as promising synthetic polymers capable of forming interpenetrating hydrogels.

Soybean chloroplast responses to enhanced ultraviolet irradiation

1993 ◽  
Vol 51 ◽  
pp. 348-349
Author(s):  
Richard F.E. Crang ◽  
Audrey E. Vassilyev ◽  
Yevgeney A. Miroslavov
Keyword(s):  
Ultraviolet Irradiation ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Ultraviolet B ◽  
Ambient Conditions ◽  
Greenhouse Soil ◽  
The Past ◽  
Computer Calculations ◽  
Clay Pots

Environmental concerns over the degradation of the earth’s stratospheric ozone layer have been expressed for the past decade in recognition that with ozone depletion, enhanced ultraviolet irradiation will be received at the earth's surface. Such increase in ultraviolet irradiation can be hypothetically determined by making appropriate computer calculations based on proposed cloud cover, season, latitude, elevation, and percent of stratospheric ozone depletion. We have proposed a 40% reduction in the ozone layer corresponding to a daily increase of 19.1 kJ in the limits of ultraviolet-B (UV-B) spectral irradiation (280-320 nm). This is within the range of realistic possibilities based on current estimated ozone depletion rates for the next 40-50 years. We wish to determine the extent to which chloroplasts are ultrastructurally altered compared with those from plants raised under ambient conditions lacking an UV-B irradiation component.Uninoculated seeds of soybean (Glycine max), cv. “Forrest” were sown in standardized greenhouse soil in 4" clay pots, watered daily, and fertilized once per week.

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