Wyszukiwarka
Filtry
wszystkich: 1656
-
Katalog
wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: LANTHANIDE-ORGANIC FRAMEWORKS
-
Cure Index demonstrates curing of epoxy composites containing silica nanoparticles of variable morphology and porosity
PublikacjaAn image was taken by Cure Index on curability of epoxy with silica nanoparticles having variable morphology and porosity. Three kinds of silica nanoparticles with non-porous curved-rod, non-porous spherical, and mesoporous spherical microstructures were synthesized and characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM) and Brunauer–Emmett–Teller analyses. Epoxy nanocomposites containing...
-
Unconditionally blue: Curing epoxy with polyethylene glycol (PEG) surface-functionalized Zn Fe3-O4 magnetic nanoparticles
PublikacjaNanoparticles govern early (chemical-controlled) and late (diffusion-controlled) stages of epoxy crosslinking, respectively. Surface functionalization of nanoparticles with macromolecules was recognized as an effective route to compensate for inadequate diffusion-controlled crosslinking. However, the effect of bulk composition amended with cations having catalytic effect towards epoxy ring opening has remained hitherto undescribed....
-
Curing epoxy resin with anhydride in the presence of halloysite nanotubes: the contradictory effects of filler concentration
PublikacjaEpoxy resins can be cured with a wide variety of curing agents such as amines and anhydrides, but anhydride curing would be more favorable for research purpose because of epoxy-anhydride curing taking place slowly at room temperature. Incorporation of natural nanosized minerals into epoxy is of environmental importance. Halloysite nanotubes (HNTs) display chemical properties similar to those of silica and alumina, and hydroxyl...
-
5-Bromo-2′-deoxycytidine—a potential DNA photosensitizer
PublikacjaA double-stranded oligonucleotide, 80 base pairs in length, was multiply labeled with 5-bromo-2′-deoxycytidine (BrdC) using polymerase chain reaction (PCR). The modified oligonucleotide was irradiated with 300 nm photons and its damage was assayed by employing DHPLC, LC-MS and denaturing polyacrylamide gel electrophoresis (PAGE). Two types of damage were demonstrated, namely, single strand breaks (SSBs) and intrastrand cross-links...
-
Properties of nano-Fe3O4 incorporated epoxy coatings from Cure Index perspective
PublikacjaThe mission of an advanced epoxy-based nanocomposite coating is to provide a given substrate with protection against an unwelcome guest; e.g. corrosive molecules/media, environmental stress, flame, thermal degradation or microorganisms. In such systems, the degree to which superior properties can be guaranteed depends on the state of network formation in the epoxy in the presence of nanoparticles. For low-filled epoxy nanocomposite coatings,...
-
Curing behavior of epoxy/Fe 3 O 4 nanocomposites: A comparison between the effects of bare Fe 3 O 4 , Fe 3 O 4 /SiO 2 /chitosan and Fe 3 O 4 /SiO 2 /chitosan/imide/phenylalanine-modified nanofillers
PublikacjaIn this study, Fe3O4 magnetic nanoparticles (MNPs) were synthesized (B-MNP) and then modified with SiO2 to form Fe3O4/SiO2 core/shell MNPs. The Fe3O4/SiO2 MNPs were chemically functionalized with chitosan so as to gain Fe3O4/SiO2/Chitosan (CH-MNP). The CH-MNP was functionalized with a macromolecule containing imide and phenylalanine precursors to gain Fe3O4/SiO2/Chitosan/imide/phenylalanine based MNPs (CH-IM-MNP). The differences...
-
Creation of Hydrogen Bonded 1D Networks by Cocrystallization of N,N`-bis(2-pyridyl) aryldiamines with Dicarboxylic Acids.Tworzenie 1D sieci krystalicznych poprzez kokrystalizację N,N` -bis(2-piry- dylo) arylodiamin z kwasami dikarboksylowymi.
PublikacjaZsyntetyzowano szereg N,N`-bis(2-pirydylo) arylodiamin, a następnie otrzymano serię kompleksów w/w amin z kwasami dikarboksylowymi oraz kwasem kwadratowym w postaci monokryształów. Jednostki N,N`-bis(2-pirydylo) arylodiamin i kwasy dikarboksylowe oddziaływują ze sobą poprzez wiązania wodorowe tworząc ośmioczłonowy cykliczny układ. W kompleksach 1:1 cząsteczki układają się w jedno-wymiarową sieć krystaliczną tworzoną przy udziale...
-
Methylene bridged glycoluril dimers: synthetic methods
PublikacjaZaprezentowano syntezę pochodnych glikolurylu tworzących ściśle sprecyzowane dimeryczne struktury w roztworze wodnym. Opisano diastereoselektywną syntezę pochodnych o strukturze amfifilowej.
-
Multivariate analysis of impedance data obtained for coating systems of varying thickness applied on steel
PublikacjaElectrochemical impedance spectroscopy (EIS) has proven to be a valuable test method for the electrochemical characterization of protective coatings on metals. The common way of analysis in impedance spectroscopy is to model the impedance spectrum by means of an equivalent circuit and to extract the quantity of interest using optimization techniques. A model, corresponding to the behavior of the sample under testing, is important...
-
Helicity discrimination in N,N'-dibenzoyl-1,2,3,4,7,8,9,10-octahydro-1,10-phenanthrolines and their thiono- and selenocarbonyl analogues by inclusion complexation with chiral diols
PublikacjaX-ray crystallographic analysis of the title compounds revealed that they assume a folded helical con- formation of an approximate C2 symmetry in the solid state. Dithioamide, diselenoamide and monoselenoamide were resolved to enantiomers by inclusion crystallization with optically active diols (TADDOLs). The absolute configuration of the guest molecules in the complexes was assigned as P. The optical activity of the resolved compounds...
-
Bio-based semi-aromatic polyesters for coating applications
PublikacjaLinear and branched bio-based semi-aromatic (co)polyesters were evaluated as resins for solvent-basedand powder coatings. Dimethyl-2,5-furandicarboxylate (DMF), 2,3-butanediol and various multifunc-tional comonomers were used to synthesize amorphous hydroxyl-end-capped (co)polyesters. The resinswere cross-linked using the -caprolactam blocked trimer of isophorone diisocyanate. Both the solvent-based and powder coatings proved to...
-
Cure kinetics of epoxy/MWCNTs nanocomposites: Isothermal calorimetric and rheological analyses
PublikacjaA combinatorial route has been applied in cure kinetics study of epoxy nanocomposites containing multi-walled carbon nanotubes (MWCNTs) based on differential scanning calorimetry and rheokinetic analyses under isothermal conditions. Pristine and amine-modified MWCNTs bearing primary and secondary amines were used at very low concentrations (0.1 and 0.3 wt.% based on epoxy weight). Model-free and model-fitting methods were applied...
-
Determination of time dependence of coated metal electrical and electrochemical parameters during exposure using principal component analysis
PublikacjaThe use of the principal component analysis (PCA) permits the complex and quantitative analysis of the time dependence of electrical and electrochemical parameters of coated metal obtained by fitting impedance data. So far, changes in electrical and electrochemical parameters during exposure were analyzed independently. In this way, some of the information contained in the relationship between changes in parameters over time are...
-
An attempt to mechanistically explain the viscoelastic behavior of transparent epoxy/starch-modified ZnO nanocomposite coatings
PublikacjaThe effects of bare and starch-modified ZnO (ZnO-St) nanoparticles on viscoelastic and mechanical properties are studied by dynamic mechanical and tensile analyses. Transparent epoxy-based nanocomposite films are prepared by incorporating bare or starch-modified ZnO particles into the epoxy matrix. The results demonstrated that ZnO particles hindered the curing reactions and hence the final properties of the cured epoxy. As a result,...
-
Flame retardant epoxy/halloysite nanotubes nanocomposite coatings: Exploring low-concentration threshold for flammability compared to expandable graphite as superior fire retardant
PublikacjaEpoxy nanocomposites containing halloysite nanotubes (HNTs) were developed and their low-concentration thresholds for thermal stability and flame retardancy were compared with that of epoxy system containing expandable graphite (EG), as a reference with superior flame retardancy. The effects of HNTs and EG on the peak of Heat Release Rate (pHRR), Total Heat Release (THR), and Time-To-Ignition (TTI) of the prepared samples were...
-
Transparent nanocomposite coatings based on epoxy and layered double hydroxide: Nonisothermal cure kinetics and viscoelastic behavior assessments
PublikacjaLayered double hydroxide (LDH) has a particular place in clay family because of its flame retardant action. The nanoplatelet-like structure of LDH makes possible development of polymer composites with cationic or anionic nature structures in which macromolecules are positioned in between nanoplatelet galleries. In this work, neat epoxy and its transparent nanocomposite coatings with sodium dodecylbenzene sulfonate (SDBS)-modified...
-
Degradation of protective coatings in steel chimneys of flue gas desulfurisation system
PublikacjaThis paper presents problems associated with corrosion of steel stacks and changes in philosophy of corrosion protection when implemented into flue gas desulphurization systems. In-situ tests were taken by means of electrochemical impedance spectroscopy at the stack which discharges flue gas before wet lime/limestone desulphurization. A very quick electrolyte absorption by the spherical infill vinylester coating was found using...
-
The changes of crosslink density of polyurethanes synthesised with using recycled component. Chemical structure and mechanical properties investigations.
PublikacjaThis paper aims at the utilisation of glycerolysate (Gly) obtained in polyurethane recycling process by means of crude glycerine, which has in its structure hydroxyl end groups that allow for further processing. Polyurethanes (PUs) were synthesised using prepolymer method with the mixture of neat polyol and glycerolysate, in different ratios, with 4,4-diphenylmethane diisocyanate (MDI). The prepolymer was subsequently extended...
-
Novel application of dynamic electrochemical impedance monitoring to a cataphoretic coating process
PublikacjaThe paper presents a novel method of on-line impedance monitoring of cataphoretic coating application process. Utilization of dynamic electrochemical impedance spectroscopy (DEIS) overcame the fundamental problem connected with non-stationarity of the aforementioned coating deposition process, which eliminates classical impedance spectroscopy technique from a real-time description of cataphoresis. The paper illustrates selected examples...
-
Stratification of nano-pigments in anti-corrosive coatings by means of magnetic field
PublikacjaThe concept of self-stratification of coatings, although attractive, causes difficulties in its practical use, especially when pigments are added to the resins. An alternative way of obtaining a multilayer structure in a single step was presented. Using the inhomogeneous magnetic field and magnetically active components of the coating, the possibility of vertically graded differentiation of the one layer properties has been verified....
-
Ring Opening of Triflates Derived from Benzophospholan-3-one Oxides by Aryl Grignard Reagents as a Route to 2‑Ethynylphenyl(diaryl)phosphine Oxides
PublikacjaA new simple method for the synthesis of 2-ethynylphenyl(diaryl)phosphine oxides via ring opening of benzophosphol-3-yl triflates has been developed. This process occurs via nucleophilic attack of a Grignard reagent at the phosphorus center, which results in ring opening and cleavage of a leaving group. The reaction proceeds under mild conditions and, within 15−60 min, leads to a library of previously unavailable 2-ethynylphenylphosphine...
-
Sensing the onset of epoxy coating degradation with combined Raman spectroscopy/atomic force microscopy/electrochemical impedance spectroscopy
PublikacjaThe paper presents the results of investigation on epoxy resin durability upon 12-week exposure to UV radiation. The aim was early determination of the onset of epoxy degradation and for this purpose an epoxy film on steel substrate systems were periodically inspected using Raman spectroscopy, atomic force microscopy and electrochemical impedance spectroscopy. The behaviour of examined polymer could be divided into three periods: immunity,...
-
Thermal decomposition of polyurethane pressure-sensitive adhesives dispersions
Publikacja -
The thermal degradation of acrylic pressure-sensitive adhesives based on butyl acrylate and acrylic acid
Publikacja -
Arylation of enelactams using TIPSOTf: reaction scope and mechanistic insight
Publikacja -
Regioselective synthesis of novel 4,5-diaryl functionalized 3,4-dihydropyrimidine-2(1H)-thiones via a non-Biginelli-type approach and evaluation of their in vitro anticancer activity
Publikacja -
Anticorrosive and antimicrobial efficiency of photopolymerizable phosphorus (meth)acrylate oligomers-based coating materials
Publikacja -
Synthesis of Polycyclic δ-Lactams with Bridged Benzomorphan Skeleton: Selectivity and Diversity Driven by Substituents
Publikacja -
Small isomeric push–pull chromophores based on thienothiophenes with tunable optical (non)linearities
Publikacja -
Enantiomeric Resolution of N,N'-Dimethyldithiodianthranilide through Diastereomeric silver(I) complex. Chiroptical spectra, racemization barrier and molecular self-assembly
PublikacjaN,N'-dimetyloditiodiantranilid, związek o chiralności płaszczyznowej, rozdzielono na enancjomery. Optycznie czynne molekuły uzyskano w wyniku tworzenia chiralnego kompleksu N,N'-dimetyloditiodiantranilidu z solą srebrową kwasu (1S)-kamforosulfonowego. W oparciu o badania rentgenostrukturalne monokryształu uzyskanego kompleksu określono absolutną konfigurację przykoordynowanego ligandu jako (R). Enancjomery N,N'-dimetyloditiodiantranilid...
-
Conformation Properties, Chiroptical Spectra, and Molecular Self-Assembly of 2,3-Piperazinodiones and Their Dithiono Analogues
PublikacjaRodzina chiralnych cyklicznych oksamidów została otrzymana przez kondensację optycznie czynnych 1,2-diamin ze szczawianem dietylu. Tionowanie produktów odczynnikiem Lawessona doprowadziło do chiralnych 2,3-dipiperazynodionów. Geometrie cząsteczkowe badano z użyciem obliczeń kwantowo-mechanicznych DFT i porównano z wynikami analizy krystalograficznej. Sześcioczłonowy pierścień heterocykliczny przyjmuje konformację półkrzesłową,...
-
Inspection of rubber linings operating in flue gas desulphurisation units
Publikacja -
Pincer Complexes Based on Phosphinoaminopyridines: Synthesis, Structural Characterization and Catalytic Applications
Publikacja -
Corrigendum to “Nonisothermal cure kinetics of epoxy/MnxFe3-xO4 nanocomposites” [Prog. Org. Coat. 140C (2020) 105505]
Publikacja -
Fluorescent Molecular Cages with Sucrose and Cyclotriveratrylene Units for the Selective Recognition of Choline and Acetylcholine
Publikacja -
Elusive π-helical peptide foldamers spotted by chiroptical studies
Publikacja -
Synthesis and Comprehensive Structural and Chiroptical Characterization of Enones Derived from (−)-α-Santonin by Experiment and Theory
Publikacja -
A configurational and conformational study of (−)-Oseltamivir using a multi-chiroptical approach
Publikacja -
Stereochemical Assingment of β -lactam Antibiotics and their Analogues by Electronic Circular Dichroism Spectroscopy
Publikacja -
Base-Catalyzed, Solvent-Free Synthesis of Rigid V-Shaped Epoxydibenzo[b,f][1,5]diazocines
Publikacja -
In Depth Analysis of Chiroptical Properties of Enones Derived from Abietic Acid
Publikacja -
Photoinduced Isomerization of 23-Oxosapogenins: Conformational Analysis and Spectroscopic Characterization of 22-Isosapogenins
Publikacja -
Chromane helicity rule – scope and challenges based on an ECD study of various trolox derivatives
Publikacja -
Amine-Catalyzed Direct Aldol Reactions of Hydroxy- and Dihydroxyacetone: Biomimetic Synthesis of Carbohydrates
Publikacja -
Bypassing the stereoselectivity issue: transformations of Kinugasa adducts from chiral alkynes and non-chiral acyclic nitrones
Publikacja -
A Unique and Stable Polyproline I Helix Sorted out from Conformational Equilibrium by Solvent Polarity
Publikacja -
Practical Method for the Absolute Configuration Assignment of tert/tert 1,2-Diols Using Their Complexes with Mo2(OAc)4
Publikacja -
The Oxolane Ring Opening of Some Muramic Acid Derivatives Under Acidic Conditions
Publikacja -
Chemical Reduction of 2,4,6-Tricyano-1,3,5-triazine and 1,3,5-Tricyanobenzene. Formation of Novel 4,4‘,6,6‘-Tetracyano-2,2‘-bitriazine and Its Radical Anion
Publikacja -
Toward an Understanding of the Chemiluminescence Accompanying the Reaction of 9-Carboxy-10-methylacridinium Phenyl Ester with Hydrogen Peroxide
Publikacja