Ru(II) Complex Based Optical Oxygen Sensors

2010 ◽  
Vol 123-125 ◽  
pp. 767-770 ◽  
Author(s):  
Maria Milanova ◽  
Joana Zaharieva ◽  
Salzitsa Anastasova ◽  
Dimitar Todorovsky
Keyword(s):  
In Situ Polymerization ◽  
Short Review ◽  
Oxygen Sensors ◽  
Working Environment ◽  
Oxygen Determination ◽  
Sensor Performance ◽  
Preparation Conditions ◽  
Working Medium ◽  
The Matrix ◽  
Lake Waters

A short review of recent investigations of the authors on the Ru(II)-based optical oxygen sensors is presented focused on the influence of: (i) type of the supporting matrix (SiO2 or polymethylmetacrylate based), (ii) precursors used (tetraethoxysilane, ormosil-type alkoxosilanes, methylmetacrylate, polymethylmetacrylate), (iii) method applied for the matrix synthesis, (iv) method for films deposition (dip- and spin coating), (v) chromophore leaching as a result of storage of the films in potentially aggressive media (water, diluted acidic and basic solutions) and (vi) working environment nature on the: a) films morphology, b) the analytical characteristics of the sensing component (linearity of the Stern-Volmer dependence, sensitivity of the device, reproducibility of the results), c) admissible parameters (pH, temperature) of the working medium. Special attention is paid on the effect of sol-sonication (as a tool against dye microcrystallization). The results obtained permit optimal precursors, sol preparation conditions and coating procedure to be recommended for gas and for dissolved oxygen measurement, respectively. The sonication of the sol ensures a rather significant improvement of the sensor performance. The strong quenching of the chromophore in the case of in-situ polymerization of the methylmetacrylate is observed.The sensing films are successfully applied for oxygen determination in natural lake waters and beer.

Preparation and Dielectric Property of Al2O3 Surface Coating Modified BaTiO3/Polyimide Composite Film

2014 ◽  
Vol 908 ◽  
pp. 63-66
Author(s):  
Ya Jun Wang ◽  
Xiao Juan Wu ◽  
Chang Gen Feng
Keyword(s):  
Dielectric Constant ◽  
Barium Titanate ◽  
Composite Film ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Chemical Properties ◽  
Dielectric Strength ◽  
Xrd Analysis ◽  
Nanocomposite Films ◽  
The Matrix

Polyimide (PI) was chosen as the matrix of the composite, barium titanate/polyimide (BT/PI) nanocomposite films were prepared by in situ polymerization. In order to improve the dispersion and the physical-chemical properties of BT surface, barium titanate was modified by Al2O3coating and modified BT/PI nanocomposite films were prepared. The prepared modified BT was characterized by X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), and the dielectric properties of the composites were characterized in detail. It was shown that surface modification with Al2O3is the chemical process and there were new substances forming. When BT was modified by 10 wt% Al2O3, the dielectric constant of the composite film was 18.96 (103Hz), the loss tangent 0.005, breakdown strength 70 MV·m-1, energy storage density 0.41 J·cm-3. The dielectric constant of BT modified by Al2O3is decreased while the dielectric strength of the modified BT/PI composite film is increased.

Leadership Constraints

2013 ◽  
Vol 9 (2) ◽  
pp. 34-60 ◽  
Author(s):  
Leslie C. Tworoger ◽  
Cynthia P. Ruppel ◽  
Baiyun Gong ◽  
Randolph A. Pohlman
Keyword(s):  
Multinational Corporation ◽  
Team Member ◽  
Virtual Team ◽  
Work Life ◽  
Working Environment ◽  
Team Leaders ◽  
High Performing ◽  
The Past ◽  
The Matrix ◽  
Life Roles

This research focused on the question: What leadership constraints contribute to the complexity of the working environment faced by global virtual team leaders and how do those leadership constraints impact the behavior of leaders when they are trying to meet team member expectations? This qualitative study of a high performing team within a multinational corporation (MNC) identified four constraints facing leaders: virtuality, globalization, the domestic workplace, and the matrix organizational structure. These constraints and their interactions contributed to the complexity that leaders faced when attempting to influence followers. While work/life roles have changed dramatically for leaders, team member expectations remain rooted in the past.

Structure and Properties of Hybrid Polyurethane Composites with Carboxyalumoxanes

2008 ◽  
Vol 587-588 ◽  
pp. 212-216 ◽  
Author(s):  
Magdalena Jurczyk-Kowalska ◽  
Joanna Ryszkowska
Keyword(s):  
In Situ Polymerization ◽  
Structure And Properties ◽  
Mechanical Mixing ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Matrix ◽  
Polyurethane Composites ◽  
Polyurethane Matrix

Carboxyalumoxanes have been incorporated into a polyurethane matrix by in situ polymerization. The filler was dispersed in the polyurethane matrix by either both ultrasonic and mechanical mixing or by mechanical mixing alone. The physico-mechanical properties of the composites have been characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Using ultrasound improves the degree of dispersion of the fillers in the matrix, but it also causes changes in the structure of the polyurethane matrix.

Oxygen Sensors Based on Luminescence Quenching: Interactions of Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) Chloride and Pyrene with Polymer Supports

1997 ◽  
Vol 51 (9) ◽  
pp. 1346-1351 ◽  
Author(s):  
Kristi A. Kneas ◽  
Wenying Xu ◽  
J. N. Demas ◽  
B. A. DeGraff
Keyword(s):  
Polymer Networks ◽  
Polymer Structure ◽  
Oxygen Sensors ◽  
Domain Model ◽  
Luminescence Quenching ◽  
Polymer Composition ◽  
Oxygen Quenching ◽  
Sensor Performance ◽  
Polymer Supports

Oxygen quenching of [Ru(Ph2phen)3]Cl2 (Ph2phen = 4,7-diphenyl-1,10-phenanthroline) and pyrene has been studied in a series of polymer networks of Gp-163 (a methacryloxy functional polydimethylsiloxane) co-polymerized with one of several co-monomers: styrene, trimethylsilyl-methylmethacrylate (T3642), vinyl-tris(2-methoxy-ethoxy)silane, or vinyl-tris(trimethylsiloxy)silane. Sensor performance was studied as a function of the polymer composition in order to delineate the important features for satisfactory O2 sensor supports. Quenching behavior was examined as a function of polymer structure, including amount and type of co-monomer. This work shows that the earlier two-domain model is too simplistic. The relative affinities of the different domains for the [Ru(Ph2phen)3]Cl2 and pyrene and the efficacy of the domains for O2 quenching are important; however, subtle changes in microstructure within domains can also strongly affect behavior. In particular, T3642 exhibits excellent structural and good quenching properties with [Ru(Ph2phen)3]Cl2.

Processing and properties of poly(ester–urethane)/modified montmorillonite nanocomposite foams derived from novel diol and tolylene-2,4-diisocyanate

2015 ◽  
Vol 30 (5) ◽  
pp. 608-624 ◽  
Author(s):  
Ayesha Kausar
Keyword(s):  
In Situ Polymerization ◽  
Layered Silicate ◽  
Decomposition Temperature ◽  
Physical Interaction ◽  
Limiting Oxygen Index ◽  
Clay Loading ◽  
Modified Montmorillonite ◽  
Nanocomposite Foams ◽  
The Matrix ◽  
Percentage Of Water Absorption

In this attempt, we have designed novel poly(ester–urethane) (PEU) using poly(di(ethylene glycol)/trimethylolpropane-alt-adipic acid), tolylene-2,4-diisocyanate, and novel diol. Later, PEU has been employed for the fabrication of nanocomposites and foams with hydroxyl-modified montmorillonite (MMT-OH) via in situ polymerization. Afterward, structure and physical properties of PEU/MMT-OH nanocomposites and foams have been explored using various techniques. Physical characteristics of nanocomposites and foams seemed to be dependent upon polyurethane structure, modification of layered silicate and physical interaction between matrix and organoclay platelets. Field emission scanning electron microscopy revealed distorted honeycomb morphology of PEU/MMT-OH 1–5 foams, while PEU/MMT-OH 1–5 nanocomposites depicted dispersed MMT-OH in the matrix. Increased cell density in nanocomposite foams was also observed relative to pure PEU foam. PEU/MMT-OH 5 (5 wt% MMT-OH) foam showed improved tensile strength of 58.1 MPa relative to PEU/MMT-OH 1 foam (56.8 MPa). The density of the foams was also increased (0.7–1.7 g cm−1) with clay loading. The 10% thermal decomposition temperature of PEU/MMT-OH 1–5 foams measured by thermogravimetric analysis was in the range of 431–465°C. Percentage of water absorption was also measured for the foam materials. Dynamic mechanical thermal analysis of PEU/MMT-OH 5 foam with 5 wt% nanofiller showed higher glass transition temperature ( Tg) of 129°C relative to PEU/MMT-OH 1 ( Tg 116°C). UL 94 and limiting oxygen index results showed that PEU/MMT-OH 1–5 foam had increased nonflammability (V-0 rating) with the clay loading. Silicate layers of MMT-OH were well exfoliated in PEU matrix due to chemical reaction between the hydroxyl of MMT-OH and functional groups of PEU. The morphology, mechanical, thermal, and flame retardant properties of PEU/MMT-OH 1–5 foams were found to be superior to those of PEU/MMT-OH 1–5 nanocomposites.

Dielectric behavior of a flexible three-phase polyimide/BaTiO3/multi-walled carbon nanotube composite film

2016 ◽  
Vol 09 (01) ◽  
pp. 1650006 ◽  
Author(s):  
Junli Wang ◽  
Shengli Qi ◽  
Yiyi Sun ◽  
Guofeng Tian ◽  
Dezhen Wu
Keyword(s):  
Composite Film ◽  
Volume Fraction ◽  
In Situ Polymerization ◽  
Composite Films ◽  
Dielectric Behavior ◽  
Low Dielectric ◽  
Three Phase ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
High Dielectric

A three-phase composite film was produced by inserting multi-walled carbon nanotubes (MWCNTs) and BaTiO3 nanoparticles into polyimide (PI). The combination of in-situ polymerization and water-based preparation involved in the experiment ensured fillers’ homogeneous dispersion in the matrix, which led to flexible shape of the composite films. The dielectric properties of composite films as a function of the frequency and the volume fraction of MWCNTs were studied. Such composite film displayed a high dielectric constant (314.07), low dielectric loss and excellent flexibility at 100[Formula: see text]Hz in the neighborhood of percolation threshold (9.02 vol%) owing to the special microcapacitor structure. The experimental results were highly consistent with the power law of percolation theory.

scholarly journals Molecular imprinting of bovine serum albumin and lysozyme within the matrix of polyampholyte hydrogels based on acrylamide, sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid and (3-acrylamidopropyl)trimethyl ammonium chloride

2021 ◽  
pp. 4-11
Author(s):  
Alexey Shakhvorostov ◽  
Sarkyt Kudaibergenov
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Ammonium Chloride ◽  
Sodium Salt ◽  
Bovine Serum ◽  
In Situ Polymerization ◽  
Trimethyl Ammonium Chloride ◽  
Cationic Monomer ◽  
The Matrix ◽  
Adsorption Desorption

Molecularly-imprinted polyampholyte (MIP) hydrogels based on nonionic monomer – acrylamide (AAm), anionic monomer – sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and cationic monomer – (3-acrylamidopropyl)trimethyl ammonium chloride (APTAC) were obtained by immobilization of bovine serum albumin (BSA) and lysozyme in situ polymerization conditions. It was found that the best amphoteric hydrogel for sorption of BSA is APTAC-75H while for sorption of lysozyme is AMPS-75H. The sorption capacity of APTAC-75H and AMPS-75H with respect to BSA and lysozyme is 305.7 and 64.1-74.8 mg per 1 g of hydrogel respectively. Desorption of BSA and lysozyme from MIP template performed by aqueous solution of 1M NaCl is equal to 82-88%. Separation of BSA and lysozyme from their mixture was performed on MIP templates. The results of adsorption-desorption cycles of BSA on adjusted to BSA polyampholyte hydrogel APTAC-75H and of lysozyme on adjusted to lysozyme polyampholyte hydrogel AMPS-75H show that the mixture of BSA and lysozyme can be selectively separated with the help of MIP hydrogels.

Mechanical Properties and Microstructure of PMMA-ZrO2 Nanocomposites for Dental CAD/CAM

2013 ◽  
Vol 785-786 ◽  
pp. 533-536 ◽  
Author(s):  
Shi Bao Li ◽  
Yi Min Zhao ◽  
Jian Feng Zhang ◽  
Cheng Xie ◽  
Dong Mei Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
In Situ Polymerization ◽  
Zirconia Ceramics ◽  
Sem Images ◽  
The Matrix ◽  
Cad Cam ◽  
Organic Resin

A novel PMMA-ZrO2 composite (PZC) was prepared by resin infiltrated to ceramic method. The composite mechanical properties were evaluated and correlated to its microstructure. Partially sintered zirconia ceramics (PSZC) were made by isostatic pressing and partially sintering. Subsequently, the PZC was prepared by vacuum infiltrating prepolymerized MMA into PSZC, followed by in-situ polymerization. When PSZC-70% was used as the matrix, the bending strength, elastic modulus, and fracture toughness of the prepared composite i.e PZC-70% were 202.56±12.09 MPa, 58.71±3.98 GPa, and 4.60±0.26 MPa·m1/2, corresponding to 25.69%, 23.31%, and 169.01% improvement, respectively, in comparison with the control matrix. Among them, the fracture toughness improvement was the most prominent. According to SEM images of the fracture surfaces, each pore of zirconia skeleton was filled by organic resin contributing to the bending strength improvement. These weak interfaces between zirconia skeleton and organic resin absorbed energy and terminated the growth of microcracks which might be responsible for significant improvement in fracture toughness. This PZC material is anticipated to be a new member of the dental CAD/CAM family.

Preparation and Properties of Polydicyclopentadiene/MMt Nanocomposites Using Supported Tungsten Catalyst

2011 ◽  
Vol 52-54 ◽  
pp. 2071-2075 ◽  
Author(s):  
Yu Qing Zhang ◽  
Yan Yi Nan ◽  
Joong Hee Lee ◽  
Yu Xin He ◽  
Da Hu Yao ◽  
...  
Keyword(s):  
Ring Opening ◽  
Mechanical Performance ◽  
In Situ Polymerization ◽  
Low Cost ◽  
Supported Catalyst ◽  
X Ray Diffraction ◽  
Ring Opening Metathesis Polymerization ◽  
Metathesis Polymerization ◽  
The Matrix ◽  
Good Catalytic Activity

Polydicyclopentadiene (PDCPD) is a kind of engineering plastic which possesses excellent mechanical performance. It can be made by dicyclopentadiene (DCPD) through Ring-opening metathesis polymerization. In this paper, a supported catalyst of WCl6-phenol on montmorillionite (MMt) was prepared, formed a high efficienct, low-cost and more stable in air, tagether with Et2AlCl as activator, to polymerize the DCPD monomer through ring-opening metathesis polymerization mechanism, and obtained a Polydicyclopentadiene/MMt Nanocomposites. The Molding of PDCPD was finally made by Gusmer-decker’s RIMcell Lt Machine, and the products were characterized by X-ray diffraction, TEM, TGA, SEM, DMA. Mechanical properties were also measured. The result showed that the supported catalyst had good catalytic activity in polymerizing DCPD. MMt was exfoliated in the matrix after the in-situ polymerization, according to the XRD and TEM, which brought about improved properties of PDCPD with small amount MMt dispersed in the matrix.

Preparation and Study of PMMA/TiO2 Nanocomposites

2011 ◽  
Vol 233-235 ◽  
pp. 1830-1833 ◽  
Author(s):  
Yong Chen ◽  
Hui Xu ◽  
Tao Sun
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Thermal Stability ◽  
In Situ Polymerization ◽  
The Matrix ◽  
Thermal Stability Of

The PMMA/TiO2 nanocomposites were prepared by in situ polymerization，the dissolution, thermal stability and the mechanical property of the nanocomposites were studied. The results indicated that nano-TiO2 may be crosslinking points in the matrix and the thermal stability of the nanocomposites became higher. As the content of nano-TiO2 increased, the mechanical properties of the nanocomposites had great changes.

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