Photoacoustic Characterization of PC/PMMA blends doped with Eu(acac)3 (original) (raw)
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Journal of Luminescence, 2006
Spectroscopic properties of blends formed by bisphenol-A polycarbonate (PC) and poly(methyl methacrylate) (PMMA) doped with Europium (III) acetylacetonate [Eu(acac) 3 ], have been studied by photoacoustic spectroscopy (PAS) and photoluminescent (PL) spectroscopy. Emission and excitation spectra, excited state decay times, and quantum efficiency have been evaluated as well. PAS studies evidenced chemical interactions between the Europium complex and the PC/PMMA blend, which presented typical percolation threshold behavior regarding the Eu 3+ content. PL spectra evidenced the photoluminescence of the Eu 3+ incorporated into the blend. Photoluminescence property enhancement was observed for the composite in comparison with the precursor compound. Optimized emission quantum efficiency was observed for the 60/40 blend doped with 2% and 4% Europium (III) acetylacetonate.
Applied Optics, 1992
A new polymeric blend, polymethyl methacrylate-poly(ethylene-co-vinylacetate) (PMMA-EVA) has been produced recently in our laboratories. The optothermal characterization of PMMA-EVA was carried out by measuring the ultraviolet photoacoustic spectra of PMMA, EVA, and PMMA-EVA (25°C, 220-350 nm), of a PMMA-EVA blend (250-750 nm) at two temperatures (19°C and 65C), and by measuring the scattering coefficient (at 514.5 nm) of PMMA-EVA versus the temperature in the range 38-86°C. Our measurements show that, in the explored thermal range, the blend undergoes a phase transition when its optical properties change drastically. The peculiar optical and thermal properties observed appear attractive for possible applications as temperature-controlled optical devices.
International Journal of Thermophysics, 2019
Recently, conductive polymers have attracted attention in the field of advanced materials. Conducting polymers include polypyrrole (PPy), which is a material with commercial applications due to its stability and electrical conductivity. As technology demands increasingly flexible devices, PPy was mixed with a biodegradable and flexible polymer, polylactic acid, in order to create a composite possessing of newer properties. As it is a new material, thermal properties of this composite such as thermal diffusivity, thermal effusivity, specific heat capacity, and thermal conductivity have been investigated through the application of photoacoustic calorimetry and photopyroelectric techniques.
Spectroscopic and thermal studies of PS/PVAc blends
Physica B: Condensed Matter, 2008
Polystyrene and polyvinyl acetate (PS/PVAc) films were blended with different contents using casting method. The effect of PS content on PVAc blends was investigated by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Ultra violet and visible studies (UV/VIS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Significant changes in FT-IR, XRD and DSC analysis are observed which reveals an interactions between the two polymers and PS/PVAc blends had good or certain miscibility. XRD scans show some changes in the intensity and the height of the amorphous halos with increased PS. UV/VIS analysis revealed that the optical band gap decreases with increasing content of PS from 5 to 4.11 eV. A single glass transition temperature for each blend was observed, this DSC results supported that the miscibility existed in the blend. The apparent activation energy (E) of the blends was evaluated using TGA analysis. The value of E was increased with the increase of PS content.
Determination of the optical absorption spectra of thin layers from their photoacoustic spectra
Optical Materials, 2018
This paper presents a new method for computations of the optical absorption coefficient spectra from the normalized photoacoustic amplitude spectra of thin semiconductor samples deposited on the optically transparent and thermally thick substrates. This method was tested on CuIn(Te0.7Se0.3)2 thin films. From the normalized photoacoustic amplitude spectra, the optical absorption coefficient spectra were computed with the new formula as also with the numerical iterative method. From these spectra, the value of the energy gap of the thin film material and the type of the optical transitions were determined. From the experimental optical transmission spectra, the optical absorption coefficient spectra were computed too, and compared with the optical absorption coefficient spectra obtained from photoacoustic spectra.
Polymer, 2005
Blends stand out as simple and cheap materials with unique properties. The miscibility of blends formed by bisphenol-A polycarbonate (PC) with poly(methyl methacrylate) (PMMA) doped with europium (III) acetylacetonate have been studied by differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and photoluminescent (PL) spectroscopy. DSC studies demonstrated that undoped PC/PMMA blends obtained by precipitation method present one glass transition temperature, evidencing their apparent miscibility. FTIR spectra revealed synergic effects in the PC/PMMA system as well as the incorporation of the Eu 3C complex. TGA analysis suggested that the Eu 3C complex remains preferably in the PC micro-phase. SEM analysis showed that europium (III) acetylacetonate is homogeneously distributed within the blend and PL spectra evidenced the photoluminescence of Eu 3C incorporated into the blend.
The Journal of Physical Chemistry C, 2017
An archetypal study is presented to correlate both the optical and photoacoustic (PA) properties for a diverse selection of dyes whose structural properties range across organic and inorganic, symmetric and asymmetric, neutral and cationic systems. Three distinct classes of molecular PA contrast-agents (MPACs) have been identified and classified according to their optical-PA response as either (i) linear absorbers (LAs)-linear PA emitter, (ii) saturable absorbers (SAs)weak PA emitter or (iii) reverse saturable absorbers (RSAs)-nonlinear PA emitter. The molecular characteristics instrumental in determining the nature of the dyes optical absorption properties, i.e. ground state molar extinction coefficient (ε g), excited state molar extinction coefficient (ε e) and excited state lifetime (τ), are discussed to aid in the interpretation of a molecule's optical vs PA response. An excellent linear PA emitter is established in crystal violet, which exhibits the strongest possible PA signal under low laser fluence conditions in both PA z-scan and tomography experiments. Ultimately, however, nonlinear reverse saturable absorber (RSA) materials are anticipated to be the most promising dye category for generation of an enhanced nonlinear PA response. Effective RSA behavior is expected for materials showing a high ratio of their excited state vs ground state absorption (ε e /ε g) whilst also possessing a long-lived excited state lifetime (τ) permitting sequential two-photon absorption. ZnTPP, C 60 , and methylene blue each show a nonlinear PA response which correlates well with their RSA optical behavior. Relative to the linear PA emission profile of crystal violet, a 3.8-fold enhancement is observed for the PA emission of ZnTPP at the highest laser fluence of 366 mJ cm-2. Similarly, C 60 and methylene blue exhibit nonlinear enhancements of 2.15-fold and 1.38-fold, respectively. Finally, to investigate the practical pros and cons with respect to application of these dyes in PA imaging