IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Investigation of spatial configuration of Polypropylene and the influence of ...IOSR Journals
Abstract: Polypropylene is considered as one of the most important plastic types because of its substantial
supreme properties such as high melting temperature, good chemical resistance and desirable mechanical
properties, and achieving desired properties of Polypropylene is a significant activity, besides, gaining this
properties is the most important economical factor in reactor polymerization which gives a considerable curve
for performance cost polypropylene. In this paper, polypropylene properties, finding physical factor_ the form,
and other factors such as molecular weight _ the type of used catalyst and molecular mass which would be
expanded to properties of final polypropylene application, are all described. The state of mechanical changes
_thermal and photic changes of polymer which are closely dependant to foresaid factors_ is also discussed in
present paper, and this indicates the path toward achieving desired quality. Keyword: Polypropylene ¸ Stereo specificity Stereochemistry ،Ziegler-Natta catalysts، Atacticity
Understanding the adsorption mechanisms in nanostructured polymer films has become crucial for their use in technological applications, since film properties vary considerably with the experimental conditions utilized for film fabrication. In this paper, we employ small-angle X-ray
scattering (SAXS) to investigate solutions of polyanilines and correlate the chain conformations with morphological features of the nanostructured films obtained with atomic force microscopy (AFM). It is shown that aggregates formed already in solution affect the film morphology; in
particular, at early stages of adsorption film morphology appears entirely governed by the chain conformation in solution and adsorption of aggregates. We also use SAXS data for modeling poly(o-ethoxyaniline) (POEA) particle shape through an ab initio procedure based on simulated
annealing using the dummy atom model (DAM), which is then compared to the morphological features of POEA films fabricated with distinct pHs and doping acids. Interestingly, when the derivative POEA is doped with p-toluene sulfonic acid (TSA), the resulting films exhibit a fibrillar morphology—seen with atomic force microscopy and transmission electron microscopy—that is consistent with the cylindrical shape inferred from the SAXS data. This is in contrast with the globular morphology observed for POEA films doped with other acids.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Investigation of spatial configuration of Polypropylene and the influence of ...IOSR Journals
Abstract: Polypropylene is considered as one of the most important plastic types because of its substantial
supreme properties such as high melting temperature, good chemical resistance and desirable mechanical
properties, and achieving desired properties of Polypropylene is a significant activity, besides, gaining this
properties is the most important economical factor in reactor polymerization which gives a considerable curve
for performance cost polypropylene. In this paper, polypropylene properties, finding physical factor_ the form,
and other factors such as molecular weight _ the type of used catalyst and molecular mass which would be
expanded to properties of final polypropylene application, are all described. The state of mechanical changes
_thermal and photic changes of polymer which are closely dependant to foresaid factors_ is also discussed in
present paper, and this indicates the path toward achieving desired quality. Keyword: Polypropylene ¸ Stereo specificity Stereochemistry ،Ziegler-Natta catalysts، Atacticity
Understanding the adsorption mechanisms in nanostructured polymer films has become crucial for their use in technological applications, since film properties vary considerably with the experimental conditions utilized for film fabrication. In this paper, we employ small-angle X-ray
scattering (SAXS) to investigate solutions of polyanilines and correlate the chain conformations with morphological features of the nanostructured films obtained with atomic force microscopy (AFM). It is shown that aggregates formed already in solution affect the film morphology; in
particular, at early stages of adsorption film morphology appears entirely governed by the chain conformation in solution and adsorption of aggregates. We also use SAXS data for modeling poly(o-ethoxyaniline) (POEA) particle shape through an ab initio procedure based on simulated
annealing using the dummy atom model (DAM), which is then compared to the morphological features of POEA films fabricated with distinct pHs and doping acids. Interestingly, when the derivative POEA is doped with p-toluene sulfonic acid (TSA), the resulting films exhibit a fibrillar morphology—seen with atomic force microscopy and transmission electron microscopy—that is consistent with the cylindrical shape inferred from the SAXS data. This is in contrast with the globular morphology observed for POEA films doped with other acids.
Polyaniline (PANI) Metal Oxide Nano Composites as a Conducting MaterialRSIS International
The combination of conducting nanoparticles and conducting polymers is a new area of research. The conducting polymer nanocomposites have both advantages of low dimensional systems and organic conductors. With this nanofibre morphology, the dispersibility and processibility of polyanilines can be improved.
The aim of this literature is to provide a survey of previous findings of researchers related to metal oxide nanocomposite polyaniline. In this paper we reviewed the properties, methods of synthesis, and various applications.
A variety of perfluorocycloalkenyl (PFCA) aryl ether monomers and polymers with enchained triarylamine units were successfully synthesized, characterized and reported here. These polymers are highly thermally stable and show variable thermal properties. Successful conver- sion of the newly synthesized TAA enchained perfluoro- cyclopentenyl (PFCP) aryl ether polymers via formylation and EAS demonstrates the synthetic versatility of TAA moiety and provides an excellent option for application specific post polymerization reactions. The cross-linking behavior of PFCP aryl ether polymers was studied under different reaction conditions. The combination of pro- cessability, thermal stabilities, and tailorability makes these polymers suitable for a wide variety of applications including electro-optics, proton exchange membranes and super-hydrophobic applications.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The cholesteric liquid-crystal poly[oxycarbonyl-1,4-phenylene-oxy-1,4 terephthaloyl-oxy-1,4-phenylenecarbonyloxy(
1,2-dodecane)] [C34H36O8]n, named PTOBDME, synthesized by polycondensation reaction from
equimolar quantities of TOBC and the racemic mixture of glycol (R-S-1,2 dodecanediol), exhibits unexpected
optical activity and chiral morphology. The structure of racemic-PTOBDME, under different polymerization
kinetics conditions, is analyzed by conventional NMR techniques and compared with those of polymer
enantiomers R-PTOBDME and S-PTOBDME obtained starting R(+)1,2 and S(-)1,2-dodecanediol respectively.
Molecular models based on the NMR signals intensities are proposed. The optical activity of racemic-
PTOBDME is evaluated by measuring the ORD values during kinetics study, and compared to the chiral
polymers. Each enantiomeric polymer seems to present the same stereoregular head-tail, isotactic structure than
the racemic, which we explain by the higher reactivity of the primary hydroxyl than the secondary one in the
glycol through polycondensation. For each enantiomer, two independent sets of signals were observed by NMR,
explained as two diastereomeric helical conformers: gg and gt, related with two possible staggered
conformations, along the copolymer backbone. Chirality in racemic-PTOBDME is proposed to be due to the
kinetic resolution of a preferable helical diastereomer, such as Sgt, with respect to the possible four forms, while
the R/S ratio of asymmetric carbon atoms remained 50:50. Chiral amplification is observed in R-PTOBDME and
S-PTOBDME due to a helical screw sense excess. Optimum yield was obtained for racemic PTOBDME, after
120 minutes polycondensated and decanted in toluene for 24 hours. Two weeks later a second fraction
precipitated from the toluene mother liquor with 67.6% chiral excess. After eight months and two weeks a third
fraction precipitated with 85.2% chiral excess.
A variety of perfluorocycloalkenyl (PFCA) arylether monomers and polymers with enchained triarylamineunits were successfully synthesized, characterized andreported here. These polymers are highly thermally stableand show variable thermal properties. Successful conver-sion of the newly synthesized TAA enchained perfluoro-cyclopentenyl (PFCP) aryl ether polymers via formylationand EAS demonstrates the synthetic versatility of TAAmoiety and provides an excellent option for applicationspecific post polymerization reactions. The cross-linkingbehavior of PFCP aryl ether polymers was studied underdifferent reaction conditions. The combination of pro-cessability, thermal stabilities, and tailorability makes thesepolymers suitable for a wide variety of applicationsincluding electro-optics, proton exchange membranes andsuper-hydrophobic applications.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
Effect of modified graphene and microwave irradiation on the mechanical and t...Mukarram Zubair
The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene-comethyl meth acrylate) [P(S-co-MMA)] polymer matrix has been studied in this article. Modification of graphene was performed
using nitric acid. P(S-co-MMA) polymer was blended via melt blending with pristine and MG. The resultant nanocomposites were irradiated under microwave at three different time intervals (5, 10, and 20 min). Compared to pristine graphene, MG showed
improved interaction with P(S-co-MMA) polymer (P) after melt mixing and microwave irradiation. The mechanism of improved
dispersion and interaction of modified graphenewith P(S-co-MMA) polymer matrix during melt mixing andmicrowave irradiation is due to the presence of oxygen functionalities on the surface of MG as confirmed from Fourier transform infrared spectroscopy. The formation of defects on modified graphene and free radicals on P(S-co-MMA) polymer chains after irradiation as explained by
Raman spectroscopy and X-Ray diffraction studies. The nanocomposites with 0.1wt% G and MG have shown a 26% and 38% increase in storage modulus. After irradiation (10 min), the storage modulus further improved to 11.9% and 27.6% of nanocomposites. The glass transition temperature of nanocomposites also improved considerably after melt mixing and microwave irradiation (but only for polymer MG nanocomposite). However, at higher irradiation time (20 min), degradation of polymer nanocomposites occurred. State of creation of crosslink network after 10min of irradiation and degradation after 20 min of irradiation of nanocomposites was confirmed from SEM studies.
Polyaniline (PANI) Metal Oxide Nano Composites as a Conducting MaterialRSIS International
The combination of conducting nanoparticles and conducting polymers is a new area of research. The conducting polymer nanocomposites have both advantages of low dimensional systems and organic conductors. With this nanofibre morphology, the dispersibility and processibility of polyanilines can be improved.
The aim of this literature is to provide a survey of previous findings of researchers related to metal oxide nanocomposite polyaniline. In this paper we reviewed the properties, methods of synthesis, and various applications.
A variety of perfluorocycloalkenyl (PFCA) aryl ether monomers and polymers with enchained triarylamine units were successfully synthesized, characterized and reported here. These polymers are highly thermally stable and show variable thermal properties. Successful conver- sion of the newly synthesized TAA enchained perfluoro- cyclopentenyl (PFCP) aryl ether polymers via formylation and EAS demonstrates the synthetic versatility of TAA moiety and provides an excellent option for application specific post polymerization reactions. The cross-linking behavior of PFCP aryl ether polymers was studied under different reaction conditions. The combination of pro- cessability, thermal stabilities, and tailorability makes these polymers suitable for a wide variety of applications including electro-optics, proton exchange membranes and super-hydrophobic applications.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The cholesteric liquid-crystal poly[oxycarbonyl-1,4-phenylene-oxy-1,4 terephthaloyl-oxy-1,4-phenylenecarbonyloxy(
1,2-dodecane)] [C34H36O8]n, named PTOBDME, synthesized by polycondensation reaction from
equimolar quantities of TOBC and the racemic mixture of glycol (R-S-1,2 dodecanediol), exhibits unexpected
optical activity and chiral morphology. The structure of racemic-PTOBDME, under different polymerization
kinetics conditions, is analyzed by conventional NMR techniques and compared with those of polymer
enantiomers R-PTOBDME and S-PTOBDME obtained starting R(+)1,2 and S(-)1,2-dodecanediol respectively.
Molecular models based on the NMR signals intensities are proposed. The optical activity of racemic-
PTOBDME is evaluated by measuring the ORD values during kinetics study, and compared to the chiral
polymers. Each enantiomeric polymer seems to present the same stereoregular head-tail, isotactic structure than
the racemic, which we explain by the higher reactivity of the primary hydroxyl than the secondary one in the
glycol through polycondensation. For each enantiomer, two independent sets of signals were observed by NMR,
explained as two diastereomeric helical conformers: gg and gt, related with two possible staggered
conformations, along the copolymer backbone. Chirality in racemic-PTOBDME is proposed to be due to the
kinetic resolution of a preferable helical diastereomer, such as Sgt, with respect to the possible four forms, while
the R/S ratio of asymmetric carbon atoms remained 50:50. Chiral amplification is observed in R-PTOBDME and
S-PTOBDME due to a helical screw sense excess. Optimum yield was obtained for racemic PTOBDME, after
120 minutes polycondensated and decanted in toluene for 24 hours. Two weeks later a second fraction
precipitated from the toluene mother liquor with 67.6% chiral excess. After eight months and two weeks a third
fraction precipitated with 85.2% chiral excess.
A variety of perfluorocycloalkenyl (PFCA) arylether monomers and polymers with enchained triarylamineunits were successfully synthesized, characterized andreported here. These polymers are highly thermally stableand show variable thermal properties. Successful conver-sion of the newly synthesized TAA enchained perfluoro-cyclopentenyl (PFCP) aryl ether polymers via formylationand EAS demonstrates the synthetic versatility of TAAmoiety and provides an excellent option for applicationspecific post polymerization reactions. The cross-linkingbehavior of PFCP aryl ether polymers was studied underdifferent reaction conditions. The combination of pro-cessability, thermal stabilities, and tailorability makes thesepolymers suitable for a wide variety of applicationsincluding electro-optics, proton exchange membranes andsuper-hydrophobic applications.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
Effect of modified graphene and microwave irradiation on the mechanical and t...Mukarram Zubair
The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene-comethyl meth acrylate) [P(S-co-MMA)] polymer matrix has been studied in this article. Modification of graphene was performed
using nitric acid. P(S-co-MMA) polymer was blended via melt blending with pristine and MG. The resultant nanocomposites were irradiated under microwave at three different time intervals (5, 10, and 20 min). Compared to pristine graphene, MG showed
improved interaction with P(S-co-MMA) polymer (P) after melt mixing and microwave irradiation. The mechanism of improved
dispersion and interaction of modified graphenewith P(S-co-MMA) polymer matrix during melt mixing andmicrowave irradiation is due to the presence of oxygen functionalities on the surface of MG as confirmed from Fourier transform infrared spectroscopy. The formation of defects on modified graphene and free radicals on P(S-co-MMA) polymer chains after irradiation as explained by
Raman spectroscopy and X-Ray diffraction studies. The nanocomposites with 0.1wt% G and MG have shown a 26% and 38% increase in storage modulus. After irradiation (10 min), the storage modulus further improved to 11.9% and 27.6% of nanocomposites. The glass transition temperature of nanocomposites also improved considerably after melt mixing and microwave irradiation (but only for polymer MG nanocomposite). However, at higher irradiation time (20 min), degradation of polymer nanocomposites occurred. State of creation of crosslink network after 10min of irradiation and degradation after 20 min of irradiation of nanocomposites was confirmed from SEM studies.
Membrane Electrode Assembly based on Sulfonated Polystyrene as Proton Exchang...AnuragSingh1049
A novel membrane electrode assembly(MEA) basedonsulfonated polystyrene was synthesized and applied to a microbial fuel cell (MFCs). In this study, membrane electrode assembly made of sulfonated polystyrene (SPS) and nafion membrane were fabricated by combining 20% AgNO3/C catalystink. The performance of membrane electrode assemblybased sulfonated polystyrene (SPS) and nafion were evaluated by measuring proton conductivity and power density.This sulfonated polystyrene of membrane electrode assembly(SPS-MEA) revealed power density was higher than that nafion non activated membrane, this is considered for membrane application of proton exchange membrane (PEM). The presence of sulfonation groups of polystyrene was characterized by Fouriertransform infrared (FTIR) and nuclearmagnetic resonance (NMR) spectroscopy. The membranetopographybefore and after the fuel cell process treatment was investigatedby atomicforce microscopy (AFM).
Thermally Stimulated Discharge Current study of PMMA:PVP blendsinventionjournals
International Journal of Pharmaceutical Science Invention (IJPSI) is an international journal intended for professionals and researchers in all fields of Pahrmaceutical Science. IJPSI publishes research articles and reviews within the whole field Pharmacy and Pharmaceutical Science, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
The electrical profiles of the renewable polymer graphite (PG) composites upon ultra violet (UV) curing were investigated. Renewable PG films were prepared by mixing with varying weight percent of graphite (with an increment of 5 wt. % of prepared graphite) up to 30 wt.% and crosslinker. Then, the composites solution was slip casted and cured upon stimulated UV irradiation (UV accelerated weathering tester) at different time exposure (up to 1000 hours) was applied. Small changes on the functional groups of the composites were observed due to UV exposure time by Fourier Transform Infrared Spectroscopy (FTIR). Suggesting that chemical crosslink and chain scissions occurred within renewable polymer graphite composites. Further electrical profile through two point probe and four point probe method recorded visibly fluctuating values for both resistivity and conductivity within its composites range. Proposed here that the removal of organic contaminants and weak materials form both renewable polymer and graphite particles through the UV curing may have an effect on the formation of conductive network stability.
Impact of Gamma Irradiation on Structural and Dielectric Properties of CuI-PV...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
The study of intermolecular interactions at interfaces is essential for a number of applications, in addition
to the understanding of mechanisms involved in sensing and biosensing with liquid samples. There are,
however, only a few methods to probe such interfacial phenomena, one of which is the atomic force
spectroscopy (AFS) where the force between an atomic force microscope tip and the sample surface is
measured. In this study, we used AFS to estimate adhesion forces for a nanostructured film of poly(oethoxyaniline)
(POEA) doped with various acids, in measurements performed in air. The adhesion force
was lower for POEA doped with inorganic acids, such as HCl and H2SO4, than with organic acids, because
the counterions were screened by the ethoxy groups. Significantly, the morphology of POEA both in the
film and in solution depends on the doping acid. Using small-angle X-ray scattering (SAXS) we observed
that POEA dissolved in amixture of dimethyl acetamide exhibits a more extended coil-like conformation,
with smaller radius of gyration, than for POEA in water, as in the latter POEA solubility is lower. In AFS
measurements in a liquid cell, the force curves for a POEA layer displayed an attractive region for pH 5
due to van der Waals interactions, with no contribution from a double-layer since POEA was dedoped. In
contrast, for pH 3, POEA was doped and the repulsive double-layer force dominated. With AFS one is
therefore able to correlate molecular-level interactions with doping and morphology of semiconducting
polymers.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
Antibacterial Activity of Schiff Bases Derived from OrthoDiaminocyclohexane, ...inventionjournals
Schiff bases (SBs) are known to possess many biological activities. In this paper we will be interested in nine SBs derived from ortho-diaminocyclohexane, meta-phenylenediamine, 1,6-diaminohexane and benzaldehydes variously substituted by nitro group. We had synthesized, characterized and tested these molecules for their antibacterial properties. Herein our study focuses in particular on the determination of quantum descriptors on which observed antibacterial activity depends, in order to be able to predict biological activities in analogue molecule series. Using quantum chemistry methods at B3LYP / 6-31G (d, p) level, we determined for each molecules, theoretical antibacterial potentials that we correlated to the experimental ones. Calculation results showed that, the energy of the Highest Occupied Molecular Orbital (EHOMO), electronegativity (χ) and electronic energy (E), are the best quantum descriptors related to the antibacterial activity values of studied molecules. The correlation coefficient R 2 indicates that 92.1% of the molecular descriptors defining this model are taken into account with a standard deviation of 0.152.The model significance is reflected by Fischer coefficient F = 7.721: Correlation coefficient of cross-validation = 0.88. This model is acceptable with . The values of the pCE50theo/pCE50exp values of the validation set tend to unity
Incorporation of Se (IV) Complexes based on Amino Acids in Biomatrixes in Hyd...IIJSRJournal
Selenium is a non-metal that shows biological interest since it is responsible for modulating various proteins at the micronutrient level in living beings. In this work, new complexes based on the Se (IV) ion with amino acids such as phenylalanine (Se-F), histidine (Se-H) and tryptophan (Se-T) were hydrothermally synthesized and characterized. These were incorporated into biomatrixes based on semi-interpenetrated polymeric networks (Semi-IPN) of collagen-polyurethane-guar gum (CPGG) by the microemulsion process using a mass ratio of 1 wt.% with respect to collagen. The structural and crystalline characteristics that the selenium-amino acid complexes show a performance in modulating the properties of the biomatrixes under study. The results indicate that the incorporation of the complex decreases the crosslinking of the hydrogel, generating granular surfaces with porosity dependent on the type of amino acid. The CPGG Se-T biomatrix shows a swelling capacity of 10200 ± 1100 higher than the CPGG base matrix; while the CPGG Se-F and CPGG Se-T biomatrixes present slow degradation at both physiological and acidic pH. Interestingly, the matrix that includes the Se-F complex significantly stimulates the metabolic activity of L929 fibroblasts for up to 48 h, stimulating their proliferation. The fibroblasts encapsulated on these novel biomatrixes show recurrent release capacity for up to 7 days, where the structure of the CPGG Se-H biomatrix exhibits greater release from the encapsulated cells. These results demonstrate that these innovative biomatrixes could be used in biomedical applications such as dermal tissue regeneration and cell release for a specific biological fate.
The study and understanding of the structure and properties of styrene/vinylester (St/VE) and styrene/unsaturated polyester (St/UP) cross-linked thermosets has received technologic and scientific attention, because these resins are widely used as matrices in composites formulations, sharing advantages, such as low room temperature viscosity coupled with good mechanical properties and low cost, plus the added chemical resistance in the case of VE.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
"Impact of front-end architecture on development cost", Viktor TurskyiFwdays
I have heard many times that architecture is not important for the front-end. Also, many times I have seen how developers implement features on the front-end just following the standard rules for a framework and think that this is enough to successfully launch the project, and then the project fails. How to prevent this and what approach to choose? I have launched dozens of complex projects and during the talk we will analyze which approaches have worked for me and which have not.
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
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Cossiello Synthetic Metals Capa
1. This article appeared in a journal published by Elsevier. The attached
copy is furnished to the author for internal non-commercial research
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220 R.F. Cossiello et al. / Synthetic Metals 158 (2008) 219–225
Fig. 1. Chemical structures of (a) poly[2-methoxy-5(2 -ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and (b) poly(styrene-co-acrylic acid-co-1-pyrenylmethyl
methacrylate) (SAA), x = 96.93, y = 3.01, z = 0.06; characterization obtained from 13 NMR and UV–vis measurements.
In this work we studied the role of the morphology on as internal standard. Absorption spectra were measured on a
device performance in blends of MEH-PPV with the copolymer Hewlett-Packard-8452A UV–vis spectrometer.
poly(styrene-co-acrylic acid) (SAA) containing with 3 mol% Molar percentages of styryl–styryl and styryl–acrylic
of acrylic acid units (Fig. 1) where the acrylic groups behave sequences were determined by integrating the areas of
ionomerically. The electrical properties of the blends with differ- the peaks at 146.6–144.8 ppm (i.e. adjacent styryl units)
ent concentrations of MEH-PPV were correlated with the blend and of 144.7–142.4 ppm (styryl units in an electron-
morphology analyzed by epifluorescence microscopy (EFM). withdrawing microenvironment) [31,32]. The molar content of
Because this ionomer is not intrinsically fluorescent, it was 1-pyrenylmethyl methacrylate (SAA-py) was determined to be
labeled with a very small amount of pyrenyl groups, strongly 0.06% using a calibration curve obtained from absorbance in the
emitting blue fluorescent molecules emitting in resonance with UV–vis spectral range in chloroform solution.
MEH-PPV absorption. Two types of films were prepared. For morphological anal-
ysis using epifluorescence microscopy and scanning electron
2. Experimental microscopy (SEM), films of MEH-PPV/SAA 25/75, 50/50,
75/25, 90/10 and 100/00 (wt.%) blends (thickness ∼80 m)
2.1. Materials were prepared by casting from 5 mg/mL chloroform solutions.
After slow evaporation under a saturated solvent atmosphere at
Acrylic acid (AA) (Sigma–Aldrich 99.0%) and styrene (S) room temperature for 30 h, they were annealed at 100 ◦ C under
(Sigma–Aldrich, 99.5%) were washed with 5% sodium hydrox- dynamic vacuum in an oven for 12 h to minimize the thermal
ide and distilled water. After, they were dried over anhydrous stress and erase thermal histories. Film thicknesses were ca.
sodium sulfate, vacuum distillated and stored under refrigera- 30–40 m. In addition, films were also prepared by spin coating
tion. The fluorescent monomer 1-pyrenylmethyl methacrylate of the same solutions, with spin rate of 1500 rpm. After deposi-
(MMA-py, 97%, polysciences), potassium persulfate (KPS, tion, these films were also annealed under the same conditions.
99%, Sigma–Aldrich), sodium dodecyl sulfate (SDS, 98%, Film thickness was around 200 nm.
Merck) and sodium bicarbonate (99%, Synth) were used as
supplied. Chloroform (Merck), dichloromethane (Merck), and 2.2. Methods
methanol (Merck) were of analytical grade. Poly[2-methoxy-
5-(2 -ethylhexyloxy)-p-phenylene-vinylene] (Mn = 86 kg/mol,
¯ Epifluorescence microscopy was performed using an inverted
Sigma–Aldrich) was used as received. Conventional emulsion microscope (Leica DM IRB) employing a mercury arc lamp
copolymerization of the monomers S, AA and MMA- (HBO-100 W) for UV–vis excitation in the wavelength range
py were carried out using previously reported protocols of 330–380 nm selected by optical filters. The emission image
[29,30]. was selected from the excitation beam by a dichroic mir-
The copolymer was characterized using FTIR, UV–vis and ror (λexc > 410 nm) [31–34]. Objective magnifications of 50×,
NMR (1 H and 13 C) spectroscopies. The FTIR spectra of the 100×, 200× and 500× were used and the images were taken
copolymers were acquired using a Bomem MB-series model with a digital camera (Samsung SDC-311) processed by Linksys
B-100 infrared spectrophotometer by casting thin films of the v. 2.38 software. Images were obtained using the epifluorescence
copolymers from chloroform solutions over NaCl windows. All configuration and were observed in terms of a blue-to-green
spectra were recorded at room temperature. Sixty-four scans region due to the fluorescence from the pyrenyl-labeled copoly-
were signal-averaged at a resolution of 2 cm−1 over the spec- mers, and a red-to-yellow region related to the emission from
tral range from 4000 to 600 cm−1 . The high-resolution 1 H and MEH-PPV. Images of thinner and thicker films were recorded.
13 C NMR spectra of the copolymers were recorded using a Scanning electron microscopy of the thinner and thicker
Bruker AC300/P, 300-MHz FT-NMR spectrometer operating at (fracture) films was obtained using a JSM-6340F microscope
resonance frequencies of 300.15 and 75.048 MHz for 1 H and operating with an accelerating voltage of 20 kV. Samples were
13 C, respectively, using CDCl as solvent and tetramethylsilane coated with a platinum/gold alloy with thicknesses around 4 nm.
3
4. Author's personal copy
R.F. Cossiello et al. / Synthetic Metals 158 (2008) 219–225 221
Original magnification was 10,000× and 5000×. Thicker films FTIR spectra (see Supporting Information—Fig. 1) exhibit
were cryogenically fractured. several IR-band characteristic of the acrylate segments, such
Steady-state photoluminescence (PL) spectroscopy was per- as: antisymmetric stretching vibrations of the CH3 groups
formed on films using an ISS-PC1 spectrofluorimeter with a (2985–2994 cm−1 ); symmetric stretching vibrations of the CH3
photon counting detection system and back-face illumination. groups (2952–2862 cm−1 ) overlapped with the stretching vibra-
The samples were excited at 348 and 460 nm and the fluo- tions of the CH2 groups (2845–2852 cm−1 ); C O stretching
rescence emission was collected in the range of 360–690 and vibrations (1730–1720 cm−1 ), bending vibrations of CH3 (1452
480–720 nm, respectively. Excitation spectra were collected and 1371 cm−1 ) and of CH2 groups 1492 cm−1 , rocking vibra-
in the range of 230–360 nm, using λem = 370 nm. Slits were tions of CH2 (757 cm−1 ) and COC stretching (1068 cm−1 ). The
selected for a spectral resolution of ±0.5 nm. IR spectra also show the characteristic absorption bands of the
Because the molar content of the 1-methylpyrenyl methacry- styrene block, such as the phenyl C C stretching vibra-
late moieties was very small, techniques like RMN and FTIR tions (1601 cm−1 ); C–H bending (698 cm−1 ); CH stretching
cannot detect the presence of such groups. Therefore, the molar of the aromatic ring (3026 cm−1 ) and a strong band from the
amount with the pyrenyl groups was determined spectropho- ( CO OH) (3432 cm−1 ).
tometricaly using a calibration curve of standard solutions of The proton 1 H NMR spectra of the copolymer show chemi-
MMA-py in dichloromethane (with molar concentrations rang- cal shifts for: the phenyl groups of the styrene blocks (6.4–7.8
ing from 5 × 10−7 to 5 × 10−5 mol L−1 ) and then measuring and 3.06–3.10 ppm), for methine ( CH ) and methylene groups
the absorbance of polymer samples in dichloromethane solu- ( CH2 ) (1.23–2.8 ppm), for methyl from 0.7 to 1.1 ppm,
tion using the value of molar absorptivity of 0.59 × 105 cm−1 at with deutered chloroform at 7.27 ppm. The 13 C NMR spec-
490 nm. tra show peaks of carbonyl in the range of 175.5–176.6 ppm
(see Supporting Information—Fig. 2), the carbon of the phenyl
2.3. Fabrication of the electroluminescent device ring bonded to the main chain occurs at 144.3–146.5 ppm,
carbons of the styrene groups are in the range from 124.2
The EL properties of the copolymers were investigated to 128.3 ppm, carbon of the methyleneoxy ( OCH2 ) are at
using a double-layer device fabricated in the configurations 66.1–67.8 ppm, carbon of the methyne of the styryl moieties
ITO/PEDOT-PSS/MEH-PPV/SAA/Ca/Al and ITO/PEDOT- ( –C –H) are in the range of 58.0–59.1 ppm, carbon of the
PSS/MEH-PPV/Ca/Al. For blends MEH-PPV/SAA blends the methylene are at 39.9–47.5 ppm, and carbon of the methyl
compositions studied were 25, 50, 75 and 90 wt.% of MEH-PPV. ( CH3 ) at 11.3–14.7 ppm. The ratio between the styryl–styryl
The ITO substrates were first cleaned by sonication in deter- and styryl–acrylic acid can be estimated using the integrated
gent followed by repeated rinsing in deionized water, acetone area observed at 146.6–144.8 (chemical shift of the styryl–styryl
and isopropanol and finally treated with dilute ozone gas. A hole units) and 144.7–142.4 ppm from the styryl groups in a microen-
injection layer of PEDOT-PSS (Bayer Co.) was spin-coated on vironment with high electronegativity such as the acrylic acid
the ITO/glass substrate (spinning speed 1500 rpm) and baked [33]. Peak of the solvent (deutered chloroform) is at 76.5 and
at 120 ◦ C for 2 h. The film thickness was 100 nm. MEH-PPV 77.9 ppm. Peaks from the pyrenyl moieties were not observed
and MEH-PPV blends in solutions (20 mg/mL in chloroform) due to the lower concentrations.
were filtered through 0.2 m Millex-FGS filters (Millipore) and The molar content of 1-pyrenylmethyl methacrylate (MMA-
than spin-coated onto the PEDOT:PSS layer in an inert nitrogen py) was z = 0.05 wt.% for the SAA copolymer, determined
gas environment. A 5 mg/mL MEH-PPV and MEH-PPV blends spectrophotometrically (see Supporting Information—Fig. 3)
solution in chloroform was used. The polymer films were typi- [33,34].
cally 75 nm thick, measured by ellipsometry, using a Si wafer.
Calcium electrodes 400 nm thick were evaporated onto the poly- 3.2. Morphology of MEH-PPV and its blends
mer films at about 0.1 Pa pressure through a mask, followed by
deposition of a protective coating of aluminum. The diode area Morphology was analyzed using thinner (200 nm) and thicker
was 6 mm2 . The devices were characterized using a spectral (30–40 m) films. For thicker films, the EFM micrographs of
measurement system constructed as described elsewhere [4,35]. MEH-PPV/SAA blends show bright spots depending on the
The devices were operated using pulsed voltage for spectral mea- composition (Fig. 2). For the 25% MEH-PPV blend discrete red
surements and dc voltage for current density determinations. The domains of MEH-PPV dispersed in a blue emitting matrix of
devices that have the emission spot occurring closer to the cen- the styrene–acrylic copolymers containing pyrenyl moieties are
ter of the device typically are less bright and less uniform than observed. For blends with higher MEH-PPV compositions the
those with emission near the cathode. morphology is more complex, in which domains of the copoly-
mer are dispersed in a continuous red matrix. However, these
3. Results and discussion domains seem to be interconnected or at least surrounded by
an interconnected phase. Images by SEM of the cryogenically
3.1. Characterization of the copolymer fractured surfaces added evidence of phase interconnection for
blends with compositions of 25% and 50% of MEH-PPV. How-
The copolymer was characterized by three techniques: ever, for compositions of 75% and 90% of MEH-PPV discrete
1H and 13 C NMR, FTIR and UV–vis spectroscopies. The domains with low interface adhesion were observed. There-
5. Author's personal copy
222 R.F. Cossiello et al. / Synthetic Metals 158 (2008) 219–225
Fig. 2. Epifluorescence optical (scale 30 m) and SEM fracture micrographs (magnification 200×, scale 10 m) of thicker MEH-PPV:SAA films (30–40 m) with
compositions of 25, 50, 75 and 90 wt.% of MEH-PPV. Films were deposited on glass by casting of chloroform solutions.
fore, although phase separation is evident, indicating that the from pure SAA, indicating that some color mixture is occurring
mutual solubility of the components is small, the phase separa- in the matrix, probably due to interpenetration of domains of
tion mechanism is complex and some spinodal decomposition is both polymers. Interpenetration is more clearly observed in both
involved. This result is in agreement with a previous report show- SEM and epifluorescence images for blends with 50% of MEH-
ing that MEH-PPV displays some miscibility when blended PPV, where the matrix seems to be richer in the SAA component
with styrene–acrylic copolymers [33,34], although it seems to while diffuse brown–red domains are distributed in the matrix.
be immiscible with poly(methyl methacrylate) and polystyrene Interconnected domains become more visible for thicker films,
[29]. It is important to point out that the color of the blue emit- as shown in Fig. 2. For the 75 wt.% of MEH-PPV there is an
ting copolymer is quenched because of the strong absorption of inversion of the phases, the matrix becomes red as shown by
the MEH-PPV in the same region. epifluorescent microscopy, although the color is not equal to that
The morphology of the thinner films was analyzed using observed for the pure MEH-PPV. Similar behavior is observed
both epifluorescence and scanning electron microscopy of the for blends with 90% of MEH-PPV where the matrix is more
film surfaces. According to the SEM micrographs of MEH- clearly formed by the conjugated polymer while the copolymer
PPV/SAA the film of blends revealed thicknesses of about composes the dispersed phase.
200 nm. The colors of the emission observed in the epifluorescence
Images by SEM and by epifluorescence of the thinner films micrographs are in agreement with the photoluminescence spec-
of polymer blends with MEH-PPV content from 25% to 90% are tra of the same blends (Fig. 4). The blue emission between 360
in Fig. 3. For the blend with 25 wt.% of MEH-PPV a red colored and 460 nm is characteristic of the domains containing SAA with
disperse phase formed by small domains is distributed in a blue attached emissive pyrenyl moieties and the red emission between
emissive matrix of SAA. However, the blue emission color of 550 and 650 nm is characteristic of the MEH-PPV domains. As
the matrix observed by epifluorescence is distinct of the color we can see, pyrenyl emission is completely quenched above
Fig. 3. Epifluorescence optical (scale 30 m) and SEM micrographs (magnification 200×, scale 1 m) of thinner films (200 nm) with compositions of 25, 50, 75
and 90 wt.% of MEH-PPV. Films were deposited on glass by spin coating of chloroform solutions.
6. Author's personal copy
R.F. Cossiello et al. / Synthetic Metals 158 (2008) 219–225 223
Fig. 4. Normalized photoluminescence spectra (SAA (from 350 to 450 nm),
MEH-PPV (from 500 to 650 nm)) of the same samples of MEH-PPV/SAA
blends as Fig. 2. λexc = 350 nm.
Fig. 5. Normalized EL spectra of ITO/PEDOT-PSS/MEH-PPV/SAA/Ca/Al
devices. Voltage = 5 V.
25% of the MEH-PPV due to overlap with MEH-PPV absorp-
tion. The photoluminescence spectrum of the 25% blend seems a larger distribution of excitons with different energies and
to be sharper and slightly blue-shifted (Table 1). Although we in different microenvironments that recombine excited states
did not perform systematic studies using films with different that undergo relaxation, leading to inhomogeneous spectral
thicknesses, this result suggests that inner filter effects may play broadening.
a role for samples more concentrated in MEH-PPV due to its
high molar absorptivity.
3.3. Electroluminescent properties of MEH-PPV/SAA
blends
The performance of the electroluminescent devices was eval-
uated by several parameters. Firstly we considered the EL
spectral (Fig. 5) changes with blend composition. Although the
spectral profile is almost independent of the composition, there
is a small red-shift of the band position with the increase of the
MEH-PPV concentration (Table 1), which could be attributed
to the inner filter effect. Nevertheless, since these samples are
thinner than those used in the PL studies of cast films we may
also consider the possibility that there is a dilution effect [22] in
blends with lower MEH-PPV concentration with a consequent
decrease of the more aggregated species.
Fig. 6 compares the EL emission of the devices and PL
emissions of a 50 wt.% blend. There is no significant change
of the peak position although a greater spectral broaden-
ing is observed for EL emission. A possible explanation for
this broadening is that while the PL arises principally from
a lower energy interchain exciton, the EL could arise from
Table 1
Spectral characteristics of the PL in blends of MEH-PPV/SAA and of EL of
ITO/PEDOT-PSS/MEH-PPV/SAA/Ca/Al devices
MEH-PPV Electroluminescence Photoluminescence
(wt.%)
Peak (nm) FWHM (cm−1 ) Peak (nm) FWHM (cm−1 )
25 578 1863 581 1060
50 580 1642 583 1538
75 582 1792 583 1538 Fig. 6. Normalized EL (- - -) (using electric field on forward bias excitation)
90 582 1676 584 1538 spectra of (a) ITO/PEDOT-PSS/MEH-PPV/Ca/Al device and (b) ITO/PEDOT-
100 584 1844 585 1096 PSS/MEH-PPV:SAA/Ca/Al devices with a 50/50 wt.% blend. For comparison
we also show the PL spectra (—) (λexc = 350 nm) of the spin-coated films.
7. Author's personal copy
224 R.F. Cossiello et al. / Synthetic Metals 158 (2008) 219–225
to the onset of significant hole injection, as mentioned above
[36].
Comparing the EL behavior with the blend morphology
defined by epifluorescence microscopy, we observe that blends
containing interconnected domains (50 and 75 wt.%) corrobo-
rate the assumption that the interfaces among domains induce
concentration of charge at the interfaces that facilitate charge
recombination [20,37]. This phenomenon arises from the self-
organizing properties of the blends, in which entropy driven
phase separation of the constituent polymers gives rise to
submicron-sized domains having characteristic compositions of
emission. Emission from domains of different composition is
controlled by the ease with which charge is injected, which in
turn depends on the applied voltage [38].
It is worth noting that the compositions that provided
improvement of the performance are similar to those observed by
others [22] using MEH-PPV/PSS-ionomer for which the PL and
EL intensities for a 50/50 blend ratio were roughly doubled com-
pared with pure MEH-PPV film. These results were explained
by a dilution effect that reduces quenching processes. In addition
to the increase of PL and EL intensities it was observed that the
turn-on voltage and the working voltage decreased significantly.
We also compared the EL versus emission intensity
for a ITO/PEDOT-PSS/MEH-PPV/Ca/Al device and several
ITO/PEDOT-PSS/MEH-PPV/SAA/Ca/Al devices (Fig. 8). As
can be seen the best device performance was obtained with
the ITO/PEDOT-PSS/MEH-PPV/SAA/Ca/Al device using a
50/50 wt.%. For comparison, the electroluminescence quantum
Fig. 7. (a) Luminance vs. voltage and (b) current density vs. voltage of the EL
yield when blended with 50 wt.% of SAA increased more than
devices ITO/PEDOT-PSS/MEH-PPV/SAA/Ca/Al at various MEH-PPV concen- four times (from 508 to 2264 cd m−2 ). The current density
trations (wt.%). The turn-on current density is ∼50 mA/cm2 at 3 V. increased almost two times, 541 mA cm2 compared with the
MEH-PPV system of 338 mA cm2 .
Fig. 7 shows the luminance versus voltage curve and the The EL spectrum in Fig. 9 is blue-shifted when the bias
current density versus voltage for the ITO/PEDOT-PSS/MEH- voltage increases. As an example, for a device using 75% of
PPV/SAA/Ca/Al devices. In general, these devices show that MEH-PPV and 25% of SAA the emission peak is observed at
both the current density and luminance increase sharply with 573 nm for 4 V, 575 nm for 8 V and 582 nm for 11 V. One expla-
voltage and have a diode character. The behavior dependents on nation for this behavior is that there is hole accumulation at the
blend composition and the brightest devices were those with 50 anode/polymer interface due to lower mobility, compared with
and 75 wt.% blends, at least for voltages up to 5 V. When the hole mobility located at the cathode interface. In other words,
imposed voltage exceeds 6 V the device with the 75 wt.% blend although the dilution effect may be important for performance
has its brightness reduced due to the lower efficiency of charge
injection. At a voltage of 5 V, the luminance of the 50 wt.% blend
is around seven times brighter than pure MEH-PPV. In addition,
the voltage corresponding to the brightest luminance decreased
from 10 V for the MEH-PPV device to 6 V for the 50 wt.% blend
device. Similar results using MEH-PPV blended with sulfonated
polystyrene have been reported and the best performance was
also observed for a device with 50/50 MEH-PPV/PS [24].
In observing the electrical response of the I–V curve (Fig. 7),
three ranges of voltage can be identified. At low voltage, space
charge limited current and ninj dominate the injected charge
contribution. Current in this regime is determined by the bulk
properties of the solid rather than contact effects. Increasing
the forward bias fills the limited number of traps occasioning a
rapid increase in the effective hole mobilities, and, therefore, a
rapid power-law increase in current (J ∝ Vn ). Above −7 V, the Fig. 8. EL vs. wavelength plots for a ITO/PEDOT-PSS/MEH-PPV/Ca/Al device
data deviate from the linear Fowler–Nordheim prediction due and ITO/PEDOT-PSS/MEH-PPV/SAA/Ca/Al devices. Voltage = 5 V.
8. Author's personal copy
R.F. Cossiello et al. / Synthetic Metals 158 (2008) 219–225 225
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