Preparation of Ultrafine Copper Particles in Poly (2-Vinylpyridine)

1988 ◽  
Vol 132 ◽  
Author(s):  
Alan M. Lyons ◽  
S. Nakahara ◽  
E. M. Pearce
Keyword(s):  
Polymer Matrix ◽  
Redox Reaction ◽  
Metallic Copper ◽  
Average Diameter ◽  
Decomposition Reaction ◽  
Polymer Precursor ◽  
Scanning Calorimetry ◽  
Copper Particles ◽  
Copper Formate ◽  
Ultrafine Copper

ABSTRACTUltrafine copper particles were prepared by the thermal decomposition of a copper formate-poly(2-vinylpyridine) complex. At temperatures above 125°C, a redox reaction occurs where Cu+2 is reduced to copper metal and formate is oxidized to CO2 and H2. The decomposition reaction was studied by thermogravimetric analysis, differential scanning calorimetry and mass spectrometry. Copper concentrations up to 23 wt% have been incorporated into the polymer by this technique. The presence of the polymeric ligand induces the redox reaction to occur at a temperature 80°C lower than in uncomplexed copper formate. Incorporation of the reducing agent (formate anion) into the polymer precursor enables the redox reaction to occur in the solid state. Films of the polymer precursor were prepared and the formation of metallic copper particles were studied by visible and infrared spectroscopy, x-ray diffraction techniques, and transmission electron microscopy. Results from these measurements indicate that spherical copper particles with an average diameter of 35angstrom are isolated within the polymer matrix. The particles are thermodynamically stable at temperatures up to the decomposition of the polymer matrix (≈350 °C), but oxidize rapidly upon exposure air.

scholarly journals The Correlation between Physical Crosslinking and Water-Soluble Drug Release from Chitosan-Based Microparticles

Pharmaceutics ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 455
Author(s):  
Emilia Szymańska ◽  
Katarzyna Woś-Latosi ◽  
Julia Jacyna ◽  
Magdalena Dąbrowska ◽  
Joanna Potaś ◽  
...  
Keyword(s):  
Drug Release ◽  
Polymer Matrix ◽  
Drug Loading ◽  
Water Soluble ◽  
Dissolution Behavior ◽  
Complex Nature ◽  
Prolonged Release ◽  
Scanning Calorimetry ◽  
Burst Effect ◽  
The Impact

Microparticles containing water-soluble zidovudine were prepared by spray-drying using chitosan glutamate and beta-glycerophosphate as an ion crosslinker (CF). The Box–Behnken design was applied to optimize the microparticles in terms of their drug loading and release behavior. Physicochemical studies were undertaken to support the results from dissolution tests and to evaluate the impact of the crosslinking ratio on the microparticles’ characteristics. The zidovudine dissolution behavior had a complex nature which comprised two phases: an initial burst effect followed with a prolonged release stage. The initial drug release, which can be modulated by the crosslinking degree, was primarily governed by the dissolution of the drug crystals located on the microparticles’ surfaces. In turn, the further dissolution stage was related to the drug diffusion from the swollen polymer matrix and was found to correlate with the drug loading. Differential Scanning Calorimetry (DSC) studies revealed the partial incorporation of a non-crystallized drug within the polymer matrix, which correlated with the amount of CF. Although CF influenced the swelling capacity of chitosan glutamate microparticles, surprisingly a higher amount of CF did not impact the time required for 80% of the drug to be released markedly. The formulation with the lowest polymer:CF ratio, 3:1, was selected as optimal, providing satisfactory drug loading and displaying a moderate burst effect within the first 30 min of the study, followed with a prolonged drug release of up to 210 min.

scholarly journals Melt-Cast Films Significantly Enhance Triamcinolone Acetonide Delivery to the Deeper Ocular Tissues

Pharmaceutics ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 158
Author(s):  
Akshaya Tatke ◽  
Narendar Dudhipala ◽  
Karthik Janga ◽  
Bhavik Soneta ◽  
Bharathi Avula ◽  
...  
Keyword(s):  
Triamcinolone Acetonide ◽  
Polymer Matrix ◽  
Rabbit Model ◽  
In Vivo Studies ◽  
Invasive Technique ◽  
Content Uniformity ◽  
Scanning Calorimetry ◽  
Ocular Tissues

Delivering an effective drug load to the posterior section of the ocular tissues, while using a non-invasive technique, has always been a challenge. In this regard, the goal of the present study was to develop sustained release triamcinolone acetonide (TA) loaded polymeric matrix films for ocular delivery. The TA-films were prepared in two different polymer matrices, with drug loadings of 10% and 20% w/w, and they were evaluated for ocular distribution in vivo in a conscious rabbit model. A 4% w/v TA suspension (TA-C) was used as a control for in vitro and in vivo studies. The TA-films, prepared with melt-cast technology, used polyethylene oxide (PEO) and Soluplus® as the polymer matrix. The films were evaluated with respect to assay, content uniformity, excipient interaction, and permeability across isolated rabbit sclera. The distribution of TA in the ocular tissues, post topical administration, was determined in New Zealand male albino rabbits as a function of dose, and was compared against TA-C. The assay of the 10% and 20% w/w film was in the range from 70–79% and 92–94% for the Soluplus® and PEO films, respectively, and content uniformity was in the range of 95–103% for both the films. The assay of the TA from Soluplus® films was less compared with the PEO films and showed an interaction with TA, as revealed by Differential Scanning Calorimetry (DSC). Hence, Soluplus® films were not selected for further studies. No interaction was observed between the drug and PEO polymer matrix. The enhancement of trans-scleral flux and permeability of TA was about 1.16 and 1.33-folds, respectively, from the 10% w/w PEO and 3.5 and 2.12-folds, respectively, from the 20% w/w PEO films, as compared with TA-C formulations. The in vivo studies demonstrate that significantly higher TA levels were observed in the anterior and posterior segments of the eye at the end of 6h with the PEO films. Therefore, the PEO based polymeric films were able to deliver TA into the back of the eye efficiently and for prolonged periods.

Preparation of a monodisperse poly (N-phenylmaleimide–acrylonitrile–styrene) structural nanolatex for heat-resistant modification of PVC

2018 ◽  
Vol 32 (3) ◽  
pp. 409-423
Author(s):  
Jin Wang ◽  
Hua Qiu ◽  
Bo Cheng ◽  
Fan Zhang ◽  
Shuhua Qi
Keyword(s):  
Electron Microscope ◽  
Elemental Analysis ◽  
Hybrid Composite ◽  
Average Diameter ◽  
Microemulsion Polymerization ◽  
Scanning Calorimetry ◽  
Thermogravimetric Analyzer ◽  
Melt Compounding ◽  
Transmission Electron ◽  
Ftir Spectrometer

A monodisperse poly ( N-phenylmaleimide–acrylonitrile–styrene) (PNAS) nanolatex was synthesized via seed microemulsion polymerization. The obtained PNAS nanolatex was then directly used as an organic nanofiller to prepare polyvinyl chloride (PVC)/PNAS hybrid composite through water blending and melt compounding. The characteristics of PNAS nanolatex were analyzed by Fourier transform infrared (FTIR) spectrometer, elemental analysis, scanning electron microscope, transmission electron microscope (TEM), dynamic laser lighting scattering (DLS), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). FTIR and elemental analysis confirmed the formation of PNAS copolymer with high monomers conversion; meanwhile, for the PNAS nanoparticles, the morphology of a well-defined core–shell spherical structure with average diameter ranging from 156 nm to 249 nm was observed. DSC analysis and TGA indicated that both polymers had excellent compatibility, and the corresponding heat resistance of PVC was greatly improved with the addition of PNAS. When PNAS loading was 50 wt%, the glass transition temperature value of PVC/PNAS hybrid composite was increased by 22.4°C, compared with that of pristine PVC. The mechanical properties of the PVC composite were also enhanced with the addition of PNAS.

scholarly journals Electrodeposition behaviour of copper from ore leachate and copper ammonium sulphate

2020 ◽  
Vol 55 (3) ◽  
pp. 229-236
Author(s):  
AI Ambo ◽  
HJ Glassa ◽  
C Peng
Keyword(s):  
Electron Transfer ◽  
Ammonium Sulphate ◽  
Redox Reaction ◽  
Chemical Reduction ◽  
Metallic Copper ◽  
Electron Transfer Reaction ◽  
Single Electron ◽  
Electrochemical Kinetics ◽  
Electron Transfer Processes ◽  
Copper Ammonium

The deposition behaviour of copper ammonia complexes from ore leachate and synthetic copper ammonium sulphate solutions was investigated using cyclic voltammetrywith platinumas counter electrode. The work is carried out to understand the deposition behaviour of the ore for hydrometallurgical and electro winning application. The chemical reduction and deposition of copper from both solutions consisted of two reversible electrochemical processes, each involving the transfer of a single electron. The Cu(NH3)4 2+ complex in the copper leachate is first reduced to Cu(NH3)4 + before being reduced to metallic copper. With synthetic copper ammonium sulphate (Cu(NH3)4SO4), the reduction to metallic copper is a ligand-coupled electron transfer reaction which proceeds as two sequential, single-electron transfer processes. The Cu/Cu(NH3)4 2+ redox reaction during deposition of copper from the leachate is fast compared to that of the Cu/Cu2+ redox reaction in the Cu(NH3)4SO4 synthetic solution. Investigation of the electrochemical kinetics shows that the linear relationship between the peak current and the square root of the scan rate is an indication that the Cu(NH3)4 + and Cu(NH3)4SO4 reduction to Cu proceeds through a diffusion-controlled process. Bangladesh J. Sci. Ind. Res.55(3), 229-236, 2020

scholarly journals Hydrothermal Synthesis of Hematite Nanoparticles Decorated on Carbon Mesospheres and Their Synergetic Action on the Thermal Decomposition of Nitrocellulose

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 968 ◽  
Author(s):  
Abdenacer Benhammada ◽  
Djalal Trache ◽  
Mohamed Kesraoui ◽  
Salim Chelouche
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Analytical Techniques ◽  
Decomposition Reaction ◽  
Decomposition Temperature ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Nano Catalyst ◽  
Average Size ◽  
A Minor

In this study, carbon mesospheres (CMS) and iron oxide nanoparticles decorated on carbon mesospheres (Fe2O3-CMS) were effectively synthesized by a direct and simple hydrothermal approach. α-Fe2O3 nanoparticles have been successfully dispersed in situ on a CMS surface. The nanoparticles obtained have been characterized by employing different analytical techniques encompassing Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The produced carbon mesospheres, mostly spherical in shape, exhibited an average size of 334.5 nm, whereas that of Fe2O3 supported on CMS is at around 80 nm. The catalytic effect of the nanocatalyst on the thermal behavior of cellulose nitrate (NC) was investigated by utilizing differential scanning calorimetry (DSC). The determination of kinetic parameters has been carried out using four isoconversional kinetic methods based on DSC data obtained at various heating rates. It is demonstrated that Fe2O3-CMS have a minor influence on the decomposition temperature of NC, while a noticeable diminution of the activation energy is acquired. In contrast, pure CMS have a slight stabilizing effect with an increase of apparent activation energy. Furthermore, the decomposition reaction mechanism of NC is affected by the introduction of the nano-catalyst. Lastly, we can infer that Fe2O3-CMS may be securely employed as an effective catalyst for the thermal decomposition of NC.

Halogenated methacrylate-based aluminum oxide (Al2O3) nanocomposites

2015 ◽  
Vol 30 (6) ◽  
pp. 762-772
Author(s):  
Kathikar Abdul Wasi ◽  
Sakvai Mohammed Safiullah ◽  
Kottur Anver Basha
Keyword(s):  
Aluminum Oxide ◽  
Polymer Matrix ◽  
Glycidyl Methacrylate ◽  
Morphological Changes ◽  
Thermal Studies ◽  
Gel Permeation Chromatography ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Initial Decomposition Temperature ◽  
Mixing Techniques

The aim of the work is to prepare the halogenated methacrylate-based polymer nano-aluminum oxide (Al2O3) composites and to study the effect of incorporated nano-Al2O3 on morphological and thermal studies. A functional 2,4,6-tribromophenyl methacrylate- co-glycidyl methacrylate copolymer microspheres (poly(TBPMA- co-GMA); pTG) by emulsion solvent evaporation techniques, whereas (2,4,6-tribromophenyl methacrylate- co-glycidyl methacrylate)-Al2O3 nanocomposites (pTG-Al2O3 nanocomposites) were prepared by solution mixing techniques. The pTG and its Al2O3 nanocomposites were structurally characterized by Fourier transform infrared (FTIR) spectroscopy. Thermal studies of pTG and its Al2O3 nanocomposites were carried out by thermogravimetric analysis and differential scanning calorimetry . The molecular weight of the pTG was determined by gel permeation chromatography. The size distribution and morphology of the pTG and its Al2O3 nanocomposites were determined by scanning electron microscopy (SEM). The FTIR results reveal that there is no significant interaction between the polymer matrix and Al2O3 nanoparticle. The significant increase in the initial decomposition temperature and glass transition temperature of pTG-Al2O3 nanocomposites compared to its polymer was due to the incorporation of nano-Al2O3 in the polymer matrix. The SEM observation provides the information about the morphological changes that arise in polymer matrix due to the incorporation of nano-Al2O3.

Nanocomposites of metallic copper and spinel ferrite films: Growth and self-assembly of copper particles

2005 ◽  
Vol 493 (1-2) ◽  
pp. 49-53 ◽  
Author(s):  
Emmanuelle Mugnier ◽  
Isabelle Pasquet ◽  
Antoine Barnabé ◽  
Lionel Presmanes ◽  
Corine Bonningue ◽  
...  
Keyword(s):  
Self Assembly ◽  
Spinel Ferrite ◽  
Metallic Copper ◽  
Copper Particles ◽  
Ferrite Films

scholarly journals Indium-tin oxide thin films by metal-organic decomposition

1993 ◽  
Vol 8 (12) ◽  
pp. 3135-3144 ◽  
Author(s):  
Dennis Gallagher ◽  
Francis Scanlan ◽  
Raymond Houriet ◽  
Hans Jörg Mathieu ◽  
Terry A. Ring
Keyword(s):  
Thermal Decomposition ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Decomposition Reaction ◽  
Scanning Calorimetry ◽  
Glass Substrates ◽  
Reducing Atmosphere ◽  
Temperature Ramp ◽  
Crystalline Films ◽  
Metal Organic

In2O3–SnO2 films were produced by thermal decomposition of a deposit which was dip coated on borosilicate glass substrates from an acetylacetone solution of indium and tin acetoacetonate. Thermal analysis showed complete pyrolysis of the organics by 400 °C. The thermal decomposition reaction generated acetylacetone gas and was found to be first order with an activation energy of 13.6 Kcal/mole. Differences in thermal decomposition between the film and bulk materials were noted. As measured by differential scanning calorimetry using a 40 °C/min temperature ramp, the glass transition temperature of the deposited oxide film was found to be ∼462 °C, and the film crystallization temperature was found to be ∼518 °C. For film fabrication, thermal decomposition of the films was performed at 500 °C in air for 1 h followed by reduction for various times at 500 °C in a reducing atmosphere. Crystalline films resulted for these conditions. A resistivity of ∼1.01 × 10−3 Ω · cm, at 8 wt. % tin oxide with a transparency of ∼95% at 400 nm, has been achieved for a 273 nm thick film.

Effect of modified microcrystalline cellulose on poly(3-hydroxybutyrate) molecular dynamics by proton relaxometry

2020 ◽  
pp. 096739112092607
Author(s):  
Filipe Antonio dos Santos Viegas Ribeiro ◽  
Maxwell de Paula Cavalcante ◽  
Maria Inês Bruno Tavares ◽  
Amanda Ramos Aragão Melo
Keyword(s):  
Molecular Dynamics ◽  
Polymer Matrix ◽  
Degree Of Crystallinity ◽  
Hybrid Films ◽  
Scanning Calorimetry ◽  
Reciprocal Influence ◽  
Proton Relaxometry ◽  
Solution Casting Method ◽  
Cellulose Concentration ◽  
Modified Cellulose

Hybrid films of poly(3-hydroxybutyrate) (PHB) and modified cellulose by solution casting method were prepared, aiming to study the influence of modified cellulose (0.25%, 0.5% and 0.75% w/w) on the structural organization and thermal properties of PHB matrix. The modified cellulose showed good dispersion in polymer matrix, due to the high compatibility between phases explained by similarity of polymer and filler structures. The composites were studied by wide-angle X-ray diffractometry, differential scanning calorimetry, thermogravimetric analysis, and time-domain nuclear magnetic resonance (NMR) spectroscopy. The conjugation of results coming from those techniques allowed to determine the cellulose concentration that had the highest influence on crystalline planes and degree of crystallinity of PHB, that is, the influence in the composite structure. The molecular dynamics obtained by NMR showed a reciprocal influence between polymer matrix and cellulose particles, enhancing the interactions present in the agglomerated particles.

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