scholarly journals Preparation of PVA Fluorescent Gel and Luminescence of Europium Sensitized by Terbium (III)

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 893
Author(s):  
Yifan Wei ◽  
Zhengquan Fu ◽  
Hao Zhao ◽  
Ruiqi Liang ◽  
Chengyu Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Film Formation ◽  
Electronic Configuration ◽  
Rare Earth Ions ◽  
Water Soluble ◽  
Fluorescence Properties ◽  
Hydroxyl Groups ◽  
Water Soluble Polymer ◽  
Quenching Effect ◽  
Wide Range

Polyvinyl alcohol (PVA) gel has a very wide range of applications in agriculture, military, industry, and other fields. As a widely used water-soluble polymer, PVA has good mechanical properties, excellent spinnability, good hydrophilicity, remarkable physical and chemical stability, good film formation, is non-polluting, and exhibits good natural degradation and biocompatibility. It is an ideal gel preparation material. Incorporation of rare-earth elements into PVA polymers can be used to prepare rare-earth luminescent gel materials. Results show that the luminescent efficiency of complexes is mainly related to their structure, ligand substituents, synergists, and the electronic configuration of doped rare-earth ions. Fluorescent gel films were prepared by adding europium, terbium, and europium/terbium co-doped into PVA, and their fluorescence properties were compared and analyzed. It was found that, in addition to the above factors, the sensitization of terbium to europium, and the fluorescence-quenching effect of hydroxyl groups, will influence the fluorescence properties. This has opened a new route for the application of rare-earth materials and may have value in the field of new materials.

Synthesis of Eu(TTA)3phen•H2O-PVP Composite Film and Study of their Luminescence Properties

2009 ◽  
Vol 79-82 ◽  
pp. 687-690
Author(s):  
Qing Liu ◽  
Zhen Xing Yao ◽  
Xian Peng Zheng ◽  
Yan Ming Yang ◽  
Qin Wei ◽  
...  
Keyword(s):  
Rare Earth ◽  
Water Molecule ◽  
Composite Film ◽  
Film Formation ◽  
Rare Earth Ions ◽  
Polymer Materials ◽  
Luminous Intensity ◽  
Rare Earth Complexes ◽  
Quenching Effect ◽  
The Eu

We obtained the Eu(TTA)3phen•H2O-PVP composite film by rare earth complexes Eu(TTA)3 phen•H2O was doped intentionally in polyvinylpyrrolidone(PVP), and the factors of effect it’s luminous intensity were investigated. The results indicate that the luminous effect of sample was best when the water and the alcohol proportion is 1: 4 in the resolver, the aggregation-time reached 12 h and the doping concentration of europioun ion reached 0.6%. The infrared spectrum analyses of sample indicate that there is an interaction between Eu(TTA)3phen•H2O and PVP. In addition, the fluorescence spectra and ultraviolet spectrum analyses of sample indicate that polymer materials can not only fix rare earth ions to enhance its luminescence intensity, but also avoid the quenching effect to rare earth caused by water molecule, through the replacement of PVP ligand to water molecule in the complex. The luminous intensity of the rare earth complexes can be greatly enhanced, and the composite film contained high amount of rare earth complexes is obtained, which laid a foundations for further study the film formation properties of rare earth complexes luminous materials.

Improved Upconversion Luminescence in Water-Soluble Yb3+/Er3+ Codoped LaF3 Nanoparticles Through Ca2+ Doping

2016 ◽  
Vol 16 (4) ◽  
pp. 3883-3885 ◽  
Author(s):  
Shihu Liu ◽  
Peng Zhang ◽  
Daguang Li ◽  
Min Lan ◽  
Zhe Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Luminescence Intensity ◽  
Upconversion Luminescence ◽  
Environmentally Friendly ◽  
Polyol Process ◽  
Rare Earth Ions ◽  
Water Soluble

Monodisperse water-soluble LaF3: Yb3+/Er3+ nanocrystals (NCs) have been successfully fabricated via a fast, facile, and environmentally-friendly polyol process with polyvinylpyrrolidone (PVP) as an amphiphilic surfactant. The obtained NCs with a small size of 18 nm can be well dispersed in hydrophilic solutions. Meanwhile, their upconversion (UC) luminescence intensity was increased through Ca2+ doping due to the decrease of symmetry around rare earth ions.

Photostimulated Luminescence Studies of Electron Trapping Materials SrS:Eu2+,RE (RE= Dy3+,Yb3+,Pr3+,Ho3+,Tm3+)

2010 ◽  
Vol 663-665 ◽  
pp. 264-267
Author(s):  
Hai Yan Du ◽  
Zhen Xing Liu ◽  
Jia Yue Sun
Keyword(s):  
Rare Earth ◽  
Rare Earth Ions ◽  
Fluorescence Properties ◽  
Electron Trapping ◽  
Photostimulated Luminescence ◽  
Trivalent Rare Earth ◽  
Sun Light ◽  
Co Doped

Trivalent rare-earth ions, Dy3+, Yb3+, Pr3+, Ho3+, Tm3+, have been investigated as the co-doped auxiliary sensitizer for the electron trapping materials SrS:Eu2+ in order to enhance the fluorescence properties. It is found that Dy3+ and Ho3+ has the optimum photoluminescence stimulated luminescence (PSL) effect among the selected trivalent rare-earth ions. All the SrS: Eu2+ samples coped by different trivalent rare-earth ions can be stimulated by 980 nm laser after exposing to the conventional sun light, and they emit PSL with the peak located at 615 nm. The present research also indicates that some co-doped rare earth ions can increase fluorescence intensities of the traditional electron trapping materials SrS: Eu2+.

scholarly journals Calcium Tungstate Doped with Rare Earth Ions Synthesized at Low Temperatures for Photoactive Composite and Anti-Counterfeiting Applications

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1214
Author(s):  
Soung-Soo Yi ◽  
Jae-Yong Jung
Keyword(s):  
Rare Earth ◽  
Light Emission ◽  
Red Light ◽  
Blue Emission ◽  
Xrd Analysis ◽  
Rare Earth Ions ◽  
Precipitation Method ◽  
Calcium Tungstate ◽  
Light Emitting ◽  
Wide Range

A precursor was prepared using a co-precipitation method to synthesize crystalline calcium tungstate. The prepared precursor was dried in an oven at 80 °C for 18 h. The dried powders, prepared without a heat treatment process, were observed in XRD analysis to be a crystalline CaWO4 phase, confirming that the synthesis of crystalline CaWO4 is possible even at low temperature. To use this crystalline CaWO4 as a light emitting material, rare earth ions were added when preparing the precursor. The CaWO4 powders doped with terbium (Tb3+) and europium (Eu3+) ions, respectively, were also observed to be crystalline in XRD analysis. The luminescence of the undoped CaWO4 sample exhibited a wide range of 300 ~ 600 nm and blue emission with a central peak of 420 nm. The Tb3+-doped sample showed green light emission at 488, 545, 585, and 620 nm, and the Eu3+-doped sample showed red light emission at 592, 614, 651, and 699 nm. Blue, green, and red CaWO4 powders with various luminescence properties were mixed with glass powder and heat-treated at 600 °C to fabricate a blue luminescent PiG disk. In addition, a flexible green and red light-emitting composite was prepared by mixing it with a silicone-based polymer. An anti-counterfeiting application was prepared by using the phosphor in an ink, which could not be identified with the naked eye but can be identified under UV light.

scholarly journals Glycol Chitosan: A Water-Soluble Polymer for Cell Imaging and Drug Delivery

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4371 ◽  
Author(s):  
Fengming Lin ◽  
Hao-Ran Jia ◽  
Fu-Gen Wu
Keyword(s):  
Antimicrobial Agents ◽  
Tumor Imaging ◽  
Water Soluble ◽  
Glycol Chitosan ◽  
Water Soluble Polymer ◽  
The Past ◽  
Wide Range ◽  
Microbial Infections ◽  
Functional Biomaterials ◽  
Shed Light

Glycol chitosan (GC), a water-soluble chitosan derivative with hydrophilic ethylene glycol branches, has both hydrophobic segments for the encapsulation of various drugs and reactive functional groups for facile chemical modifications. Over the past two decades, a variety of molecules have been physically encapsulated within or chemically conjugated with GC and its derivatives to construct a wide range of functional biomaterials. This review summarizes the recent advances of GC-based materials in cell surface labeling, multimodal tumor imaging, and encapsulation and delivery of drugs (including chemotherapeutics, photosensitizers, nucleic acids, and antimicrobial agents) for combating cancers and microbial infections. Besides, different strategies for GC modifications are also highlighted with the aim to shed light on how to endow GC and its derivatives with desirable properties for therapeutic purposes. In addition, we discuss both the promises and challenges of the GC-derived biomaterials.

scholarly journals Optimized Loading of Carboxymethyl Cellulose (CMC) in Tri-component Electrospun Nanofibers Having Uniform Morphology

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2524
Author(s):  
Motahira Hashmi ◽  
Sana Ullah ◽  
Azeem Ullah ◽  
Muhammad Akmal ◽  
Yusuke Saito ◽  
...  
Keyword(s):  
Carboxymethyl Cellulose ◽  
Water Solubility ◽  
Continuous Production ◽  
Weight Ratio ◽  
Electrospun Nanofibers ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Wide Range ◽  
Aqueous Conditions ◽  
Water Holding

Cellulose is one of the most hydrophilic polymers with sufficient water holding capacity but it is unstable in aqueous conditions and it swells. Cellulose itself is not suitable for electrospun nanofibers’ formation due to high swelling, viscosity, and lower conductivity. Carboxymethyl cellulose (CMC) is also super hydrophilic polymer, however it has the same trend for nanofibers formation as that of cellulose. Due to the above-stated reasons, applications of CMC are quite limited in nanotechnology. In recent research, loading of CMC was optimized for electrospun tri-component polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and carboxymethyl cellulose (CMC) nanofibers aim at widening its area of applications. PVA is a water-soluble polymer with a wide range of applications in water filtration, biomedical, and environmental engineering, and with the advantage of easy process ability. However, it was observed that only PVA was not sufficient to produce PVA/CMC nanofibers via electrospinning. To increase spinnability of PVA/CMC nanofibers, PVP was selected as the best available option because of its higher conductivity and water solubility. Weight ratios of CMC and PVP were optimized to produce uniform nanofibers with continuous production as well. It was observed that at a weight ratio of PVP 12 and CMC 3 was at the highest possible loading to produce smooth nanofibers.

Modification of Near-Wall Turbulent Structure in Channel Flow by Dosing a Small Amount of Polymer Solution

2017 ◽  
Author(s):  
Yushi Okamura ◽  
Tomohiro Kurose ◽  
Yasuo Kawaguchi
Keyword(s):  
Velocity Distribution ◽  
Polymer Solution ◽  
Polymer Concentration ◽  
Water Soluble ◽  
Polymer Additives ◽  
Normal Velocity ◽  
Water Soluble Polymer ◽  
Low Speed ◽  
Wide Range ◽  
Near Wall

The phenomenon known as Toms effect can impart viscoelasticity to a water flow when a small amount of water-soluble polymer is added. The resulting viscoelastic fluid generates viscoelastic stress in the flow, dramatically reducing the turbulent stress. In this study, the spatial distribution of velocity is measured using a stereo-PIV method in the streamwise-spanwise plane parallel to the wall. Modification of the near wall turbulence by the polymer solution blown slowly from a permeable wall was investigated by analyzing the velocity distribution acquired by stereo-PIV measurements. Experimental results reveal that streamwise local mean velocity decreases as the dosed polymer concentration increases. The skewness factor at this height shifts from 0 to positive by adding the polymer, which indicates intensified turbulent coherent structure. Moreover, the spatial two-point correlation function calculated from streamwise velocity fluctuations maintains its high correlation with the streamwise direction. It is consistent with the finding from the instantaneous velocity distribution, which shows that the flection of low-speed streaks is suppressed. Next, it is revealed that the normal velocity at the wall for low-speed fluid is decreased dramatically by polymer additives. Moreover, applying the quadrant analysis, it is confirmed that ejection events are suppressed with decreasing normal velocity at the wall. Suppression of ejection motion affects to the turbulence in the log law layer. We conclude that this is one reason that turbulence is suppressed in a wide range of the shear layer by polymer additives present only in the vicinity of the wall.

Crosslinking of Guar and Guar Derivatives

SPE Journal ◽  
2007 ◽  
Vol 12 (03) ◽  
pp. 316-321 ◽  
Author(s):  
Cuiyue Lei ◽  
Peter E. Clark
Keyword(s):  
Polymer Solution ◽  
Critical Concentration ◽  
Polymer Concentration ◽  
Water Soluble ◽  
Solution Behavior ◽  
Water Soluble Polymer ◽  
Important Indicator ◽  
Low Concentrations ◽  
Wide Range ◽  
Overlap Concentration

Summary Crosslinking of guar and guar derivatives has played a major role in improving stimulation of oil and gas wells. While crosslinking has been used for a number of years, many facets of crosslinked systems are still not well understood. Part of the problem is that the traditional methods of determining the properties of crosslinked fluids work well for obtaining the data necessary for treatment design, but yield little insight into the nature of the crosslinked system. A good example of this is found in the development of low polymer concentration crosslinked gels. These gels are important because they lower costs and help to minimize formation damage. In this paper, methods for predicting crosslinkability at low concentrations are reported. The polymer literature is filled with methods for characterizing polymer solutions almost none of which find wide use in the development of crosslinked fracturing fluids. Dawson et al. (2000) first reported that the concentration at which a polymer solution transitions from dilute to semidilute could be used as a method for determining the potential for low concentration crosslinking in guar or guar-derivative solutions. To test this assertion, we have conducted a series of experiments that not only shows that the dilute-semidilute transition concentration is an important indicator for the polymers used in this study, but also presents a framework for exploring the potential of other polymer systems. These experiments show conclusively that low-polymer concentration crosslinking is strongly related to the value of the critical overlap concentration, c*. Both the critical overlap concentration and the critical crosslinking concentration increase in the order guar-3 < CMG < CMHPG < guar < HPG. In addition, we show that the critical crosslinking concentration for the range of polymer-crosslinking systems studied is correlated to the critical overlap concentration (). A strong case is presented for the ability to crosslink at low concentrations is a strong function of the polymer type and a weak function of the crosslinker type. Introduction Water-soluble polymers have been used for a number of years as thickening agents for stimulation fluids. Crosslinking was developed to improve the performance of these materials without increasing polymer concentration. Over the years, a number of different crosslinking agents have been used with success. There are several good discussions of polymer and crosslinking systems available (Economides and Nolte 1989; Gidley et al. 1989), and it is not the purpose of this paper to expand these discussions. Rather, we will approach the problem of crosslinking from the prospective of the molecular or solution properties that control or influence crosslinking. When a water-soluble polymer is hydrated, the viscosity of the resulting solution increases as a function of concentration. Starting at low concentrations and building to high concentrations, the viscosity appears to exhibit an exponential increase. This phenomenon has been studied for a wide range of polymer—solvent systems and seems to be universal. Early work divided the viscosity—concentration curve into two regions (Menjivar 1986; Robinson et al. 1982) that were separated at a critical concentration labeled c*. As the understanding of polymer solution behavior progressed and more sensitive instruments and experimental techniques were developed, the solution behavior was determined to be more complex (Rubinstein and Colby 2003).

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