Doped Polystyrene Research Articles

Trinuclear Cyclometalated Iridium(III) Complex Exhibiting Intense Phosphorescence of an Unprecedented Rate.

Herein, we present two novel cyclometalated Ir(III) complexes of dinuclear and trinuclear design, Ir2(dppm)3(acac)2 and Ir3(dppm)4(acac)3, respectively, where dppm is 4,6-di(4-tert-butylphenyl)pyrimidine ligand and acac is acetylacetonate ligand. In both cases, rac-diastereomers were isolated during the synthesis. The materials show intense phosphorescence of outstanding rates (kr = ΦPL/τ) with corresponding radiative decay times of only τr = 1/kr = 0.36 μs for dinuclear Ir2(dppm)3(acac)2 and still shorter τr = 0.30 μs for trinuclear Ir3(dppm)4(acac)3, as measured for doped polystyrene film samples under ambient temperature. Measured under cryogenic conditions, radiative decay times of the three T1 substates (I, III, and III) and substate energy separations are τI = 11.8 μs, τII = 7.1 μs, τIII = 0.06 μs, ΔE(II-I) = 7 cm-1, and ΔE(III-I) = 175 cm-1 for dinuclear Ir2(dppm)3(acac)2 and τI = 3.1 μs, τII = 3.5 μs, τIII = 0.03 μs, ΔE(II-I) ≈ 1 cm-1, and ΔE(III-I) = 180 cm-1 for trinuclear Ir3(dppm)4(acac)3. The determined T1 state ZFS values (ΔE(III-I)) are smaller compared to that of mononuclear analogue Ir(dppm)2(acac) (ZFS = 210-1 cm). Theoretical analysis suggests that the high phosphorescence rates in multinuclear materials can be associated with the increased number of singlet states lending oscillator strength to the T1 → S0 transition.

Recent review on metal oxides nanostructures doped polystyrene for biological and industrial applications

Polymers have many applications in various medical and industrial approaches. One of these polymers is polystyrene which has special properties to be considered as promising material in different optics, biomedical, and electronics fields. The addition of metal oxides nanoparticles to polystyrene have huge applications in different approaches. This article includes a recent review on metal oxide NPs doped polymer (such as polystyrene). The previous studies demonstrated the polystyrene nanocomposites comprised numerous applications in the electronics, sensors, optical optoelectronics, and biomedical fields.

X-Ray Photoelectron Spectroscopy of Polystyrene Composite Films

In this paper, X-ray Photoelectron Spectroscopy (XPS) measurements were obtained to determine the chemical structure of these polystyrene (PS) doped and undoped thin films. The purpose is to analyze the graphs and binding energies of each element to determine. The XPS analysis of these pure PS compared doped PS thin film does show a tunable potential for optimum properties. PS has a relative basic host matrix, and it is our hypothesis that first, we can show that XPS can be a useful and resourceful tool in characterizing these thin films for chemical structure and binding information. Secondly, we intend to show that through the addition of dopants, we can affect the binding energies. The results show the impact on O1s binding energies ± 4.43-5.57 eV and for C1s ± 1.45 -9.37 eV. These analyses have been performed in several studies on polymer nanocomposite materials. Here, we introduce the use of the XPS analysis in recent notable polymer nanocomposite studies for various target applications.

Effects of non-thermal plasma jet treatment of Pure/Doped Polystyrene thin films on UV-Vis optical properties

Non-thermal Cold Atmospheric Plasma (CAP) to improve optical property of pure and doped polystyrene (PS) thin films using He and Ar gas. These thin films were fabricated using the solution cast method. Surface treatment of PS thin films were performed by CAP. To analyze the effect of plasma treatment, the optical properties of the thin films were measured and derived by UV-Vis spectroscopy in wavelength range of 300-700 nm. Absorbance, transmittance, extinction coefficient, energy band gap, and optical conductivity before and after Cold jet plasma treatment (CJT) were compared. The results from Ar and He were similar in effectiveness. The treatment did have an impact on the optical properties of these PS thin films. This data will help to substantiate the use of CJT to enhance optical properties of polymer thin films.    

Study of interfaces in polymer-metal oxide films and free-volume hole using low-energy positron lifetime measurements

Abstract To reveal how the distribution of different nano fillers affect the UV-shielding efficiency of their polymer-based composites and to further develop a simple strategy to refrain the erection of the composites, we prepared ZnO doped polystyrene (PS/ZnO) and TiO2 doped polystyrene (PS/TiO2) films by the solution cast technique with different concentrations of ZnO and TiO2 (0.25%, 0.5%, 0.75% and 1%.). Contrary to the common observation, the better tunability for UV shielding efficiency was found in the case of TiO2 as compared to ZnO. This is mainly due to the appearance of a rod like structure on neat PS which has improved the dispersion as well as provides a higher interface area that enhanced the UV-absorption efficiency of the PS matrix. This analysis is equally supported by the PALS study where the free volume was closely associated with the interfacial interaction between the filler and the PS matrix. These observations recommend that the better dispersion of filler particles leads a stronger interfacial interaction and enhances the UV-protection efficiency of the composite materials.

Preparation and Characteristics Study of Polystyrene/Porous Silicon Photodetector Prepared by Electrochemical Etching

Novel doped polystyrene (PS)/porous silicon (PSi) heterojunction photodetector prepared by solution cast and electrochemical techniques is proposed here. The structural and optical properties of polystyrene film and porous silicon surface were investigated using X-ray diffraction (XRD), scanning electron microscope, Fourier transformed infrared (FT-IR), and UV–Vis spectrophotometer. XRD data confirmed that the PS film was amorphous in nature and the porous silicon was nanocrystalline. The optical properties showed that the average optical transmittance and the optical energy gap of PS film were 80% and 3.2 eV, respectively. The electrical properties revealed that the electrical resistivity and mobility of the doped polystyrene film were 3 × 104 Ω cm and 4.5 × 10−5 cm2 V−1 s−1, respectively. Photoluminescence PL of porous silicon was investigated. Dark I–V characteristics revealed that the PS/PSi heterojunctions prepared with an etching time of 5 min exhibited better-rectifying properties than that of PS/PSi heterojunction prepared at 10 min. The figures of merit of the photodetectors such as spectral responsivity, external quantum efficiency, and detectivity were investigated and compared with Au/PSi Schottky photodetectors. Minority carrier lifetime of the photodetectors was measured using open circuit voltage decay method.

Effect of γ-irradiation on optical properties of Eu2 O3 -doped polystyrene polymer films.

In the present study, europium (III) oxide (Eu2 O3 )-doped polystyrene (PS) polymer films were synthesized using a solution-casting technique for different filler levels. These films were irradiated with 5, 25 and 50kGy γ doses and characterized using various techniques, viz. X-ray diffraction (XRD), and UV-visible and photoluminescence (PL) spectroscopies as a function of composition level and radiation dose. The UV-visible spectra indicated a decrease in the optical direct band gap of composite films with increasing concentrations of dopant and radiation dose. The band gaps of composites obtained using Tauc's equation were found to be 4.38, 4.37, 4.36and 4.34eV for 0, 1, 3 and 5% Eu2 O3 -doped PS respectively, while the band gaps of 5% Eu2 O3 -doped PS polymer films irradiated with 5, 25 and 50kGy were found to be 4.30, 4.26 and 4.21eV, respectively. Photoluminescence (PL) emission spectra showed the characteristic peaks of Eu3+ at 595nm, 612nm and 617nm with an excitation wavelength of 247nm. The intensity of characteristic peaks of Eu3+ was observed to increase with increasing filler concentration, while it was found to decrease with increasing radiation dose. The polymer under study may be useful in accidental dosimetry. As photoluminescence studies are carried out after a gap of 200h from irradiation and PL emission of γ-irradiated polymer yielded 10 times emission when compared with non-irradiated polymer.

Water-equivalence of ZrO2 doped polystyrene by Monte Carlo simulation

Objective To design water-equivalent plastic scintillator detector for the measurement of absorbed dose in tumor radiotherapy. Methods The concentration of ZrO2 to be doped in polystyrene was estimated according to the empirical formula, and then the Monte Carlo program Geant4 (GEometry And Tracking 4) was used to simulate the energy deposition and transport process of X-rays with different energies in water, solid water RW34 (composed of 2.1 wt% TiO2 doping polystyrene) and different concentrations of ZrO2 particles doped in polystyrene. The dose and attenuation coefficients were compared among different materials at different depths of water. Results The doses at different depths and the attenuation coefficient of polystyrene (doped with about 0.4 wt% ZrO2 nanoparticles) were much more consistent with those of water and even exhibit much better water-equivalence than RW34. Conclusions The simulation results provide the basis for the development of water-equivalent scintillator. Key words: Geant4; Water-equivalent; ZrO2nanoparticle; Polystyrene

Nonlinear Optical Characteristics of Crystal VioletDye Doped Polystyrene Films by Using Z-Scan Technique

Z-scan technique was employed to study the nonlinear optical properties (nonlinear refractive index and nonlinear absorption coefficient) for crystal violet doped polystyrene films as a function of doping ratio in chloroform solvent. Samples exhibits in closed aperture Z-scan positive nonlinear refraction (self-focusing). While in the open aperture Z-scan gives reverse saturation absorption (RSA) (positive absorption) for all film with different doping ratio making samples candidates for optical limiting devices for protection of sensors and eyes from energetic laser light pulses under the experimental conditions.

Eu3+ -doped polystyrene and polyvinylidene fluoride nanofibers made by electrospinning for photoluminescent fabric designing.

Eu3+ -doped polystyrene and polyvinylidene fluoride (PVDF/Eu3+ and PS/Eu3+ ) nanofibers were made using electrospinning. These fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDX) and photoluminescence (PL). Spectral analysis of PVDF/Eu3+ and PS/Eu3+ nanofibers was based on their emission spectra. A bright red emission was noticed from Eu3+ that was assigned to the hypersensitive 5 D0 →7 F2 transition. The enhanced intensity ratios of 5 D0 →7 F2 to 5 D0 →7 F1 transitions in the nanofibers indicated a more polarized chemical environment for the Eu3+ ions and greater hypersensitivity for the 5 D0 →7 F2 transition, which showed the potential for application in various polymer optoelectronic devices. The Eu3+ -doped polymer (PVDF/Eu3+ and PS/Eu3+ ) nanofibers are suitable for the photoluminescent white light fabric design of smart textiles. This paper focuses on the potential application of smart fabrics to address challenges in human life.

Preparation and properties of RE 3+ doped luminescent co-polymer by solution copolymerization

Bonded type RE 3+ doped luminescent co-polymer was synthesized by solution free radical copolymerization. The influence of charge sequence, monomers and co-polymerized method on properties and structures of the co-polymers was studied. The emission intensity of the co-polymers at different RE 3+ concentrations was tested. The results showed that the co-polymers of Eu-PSt and Eu-PMMA both had wide absorption peak at 200–400 nm and the strongest peak appeared at 235 nm. The fluorescent intensity of Eu 3+ doped polystyrene copolymer was stronger than that of Eu 3+ doped PMMA copolymer. The characteristic emission of europium ions was observed in the co-polymers. The copolymer doped with rare earth elements showed the “sensitization effect” for the central ions. The bonded-type rare earth copolymer not only enhanced the energy transfer efficiency, but also improved the fluorescence intensity by increasing the rigidity of main and side chain.

SiO 2 nanoparticles as scatterers for random organic laser action in red fluorescent dye 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran doped polystyrene films

Random multimode lasers are achieved in 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped polystyrene thin films by introducing silicon dioxide (SiO2) nanoparticles as scatterers. The devices emit a resonance multimode peak at a center wavelength of 640 nm with a mode linewidth less than 0.87 nm. The threshold excitation intensity is as low as 0.25 mJ pulse−1 cm−2. It can be seen that the microscopic random resonance cavities can be formed by multiple scattering of SiO2 nanoparticles. The transport mean free length is estimated to be about 156 μm. The demonstration of random organic lasers opens up the possibility of using scattering as an alternative source of coherent light emission.

Random lasing emission from a red fluorescent dye doped polystyrene film containing dispersed polystyrene nanoparticles

The authors report a random lasing emission from 4-(dicy-anomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran doped polystyrene thin films by introducing polystyrene nanoparticles. The aspects of concentration and diameter of polystyrene nanoparticles have been intensively investigated and found that the lasing occurs due to the scattering role of polystyrene nanoparticles. The devices emit a resonance multimode peak centered at a wavelength of 630nm with a mode linewidth of less than 0.35nm and exhibit threshold excitation intensity of as low as 0.06mJpulse−1cm−2. The microscopic laser cavities formed by multiple scattering have been captured. The demonstration of random laser opens up the possibility of using organic scattering as alternative sources of coherent light emission.

Fabrication and Characterization of Dye-doped Polymeric Mode Filter

Bromocresol Purple (BCP) dye doped SAN films were fabricated by varying the concentration of dye and studied the effect on the optical parameters. The transmission of BCP was above 85% in the range of 550–900 nm. At 0.03% of dye the films showed minimum propagation losses (0.7 db/cm). A mode filter was fabricated using BCP doped SAN films and Methyl Red doped polystyrene films were coated over them. The concentration of Methyl Red in polystrene and BCP in styrene acrylonitrile was varied from 0.01 to 0.05% (w/v). It was observed that at 0.03% of Methyl red and BCP the propagation losses (0.57 db/cm) were minimum in the multilayer structure. BCP doped polymer films can be used to fabricate other photonic devices too.

On the Involvement of Geminate Pairs in Radiation-Induced Conductivity of Polystyrene

Basic parameters of the generalized Rose–Fowler–Weisberg theory were experimentally determined for polystyrene. The obtained data were used to comprehensively analyze the evolution of geminate pairs in this polymer. It was shown that the generation of the prompt component of radiation-induced conductivity occurs by the trapping mechanism with two charge carrier states involved, the quasi-free and trapped. This generation under equilibrium transport conditions (diffusivity and mobility of carriers are constant) reportedly ensured by the geminate recombination itself was not observed in a real experiment. With allowance for dispersive transport of holes (the major carriers), the lifetime of geminate pairs were found to be as long as a few hundred of milliseconds at 300 K. The published data on the formation and decay kinetics in doped polystyrene upon its pulse radiolysis or photolysis were thoroughly analyzed. It was shown that, at ultrashort times before localization of generated carriers, the contribution of electrons to the observed conductivity prevails, although the basic contribution is made by holes in later times.

Spectral and Time Domain Studies of Accumulated Photon Echo

Abstract Multishot or single-shot retrieval of femtosecond echo signal without substantial spectral distortion was experimentally demonstrated for a H2-octaethylporphine doped polystyrene sample. Upto 104 single-shot readout cycles using a femtosecond pulse were observed without substantial echo signal degradation. The echo decay time was determined for this sample to be (50 ± 15) ps.

2-(2'-Hydroxyphenyl)benzothiazoles, -benzoxazoles, and -benzimidazoles for plastic scintillation applications

A new series of fluorescent compounds has been tested as dopants for plastic scintillation applications. Several 2-(2{prime}-hydroxyphenyl)benzothiazole, -benzoxazole, and -benzimidazole derivatives have been prepared and studied in a polystyrene matrix. Each derivative has been added to a styrene solution which has been thermally polymerized. The transmittance, fluorescence, and light yield characteristics of these compounds in polystyrene have been determined. Their emission time distributions have also been measured, and the decay time constants have been calculated from these data. In addition, the doped polystyrene samples have been irradiated to a total dose of 10 Mrad, utilizing a {sup 60}Co source in order to evaluate their susceptibility to radiation-induced damage. 6 figs., 1 tab.

Resonant third-harmonic generation in all-trans β-carotene: The vibronic origins of the third-order nonlinear susceptibility in the visible region

The dispersion of the modulus of the third-order nonlinear susceptibility, ‖χ(3)zzzz(−3ω;ω,ω,ω)‖, of an all-trans β-carotene doped polystyrene thin film has been measured by third-harmonic generation throughout the 1 1Bu absorption band of the β-carotene. The observed dispersion is interpreted in terms of a three-electronic state model including explicit regard to six Franck–Condon active normal modes in the resonant electronic state. Both the sum-over-states method and, equivalently, the time domain approach are used. A fit of the three-state model to the data shows that the large nonlinear susceptibility of β-carotene in this wavelength range can be explained by strong dipole coupling between the strong one-photon allowed 1 1Bu state and a nearby two-photon allowed n 1Ag state. The electric dipole transition moment between the 1 1Bu excited state and the n 1Ag excited state, located at 22 200 cm−1, was determined to be 31 D.

Pyroelectric currents in undoped and Fe‐doped polystyrene films

AbstractThe pyroelectric behaviour of undoped and Fe3+ doped polystyrene films was studied at different polarizing fields, polarizing temperatures, and doping concentrations. The pyroelectric currents were positive throughout and showed a significant increase with increasing dopant concentration, polarizing field and temperature. The origin of pyroelectricity has been attributed to space charge polarization.

Electron conduction in fe‐doped polystyrene films

AbstractThe DC electrical conductivity of pure and Fe3+‐doped polystyrene films has been studied at various bias field strengths in the temperature range 304–392K. Doped films showed increased conductivity compared with undoped films up to 0.5% dopant concentration; beyond this concentration there was a decrease in the conductivity. The increase in conductivity for lower doping concentrations (0.25% and 0.5%) is attributed to the formation of charge transfer complexes. The decrease in the electrical conductivity and the increase in the activation energy at more than 0.5% dopant concentration is due to the formation of molecular aggregates. For undoped films the activation energies in the low temperature region were found to be higher than those at higher temperatures. Also, with increasing bias field strength, the activation energies showed a decrease at all temperatures studied. It is suggested, on the basis of the magnitudes of the activation energies, that electronic conduction is the dominant charge transport mechanism both at low and high temperatures.