Structural characterization, thermal properties, and density functional theory studies of PMMA‐maghemite hybrid material

Rocha, Marcus V. J.; Carvalho, Hudson Wallace Pereira de; Sarmento, Víctor Hugo Vitorino; Craievich, A. F.; Ramalho, Teodorico C.

doi:10.1002/pc.23154

Cited by 8 publications

(2 citation statements)

References 29 publications

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“…Density functional theory (DFT) calculation is a popular, efficient, and reliable method to explore the essential characteristics of different chemical reactions. In recent years, the density functional formalism has been the basis of many calculations of molecules, atomic clusters, and complex systems, because it can provide a reliable prediction of reaction pathways and related energy barriers .…”

Section: Introductionmentioning

confidence: 99%

Reaction Mechanisms and Kinetics of the Melt Transesterification of Bisphenol‐A and Diphenyl Carbonate

Zhao

2018

Int J of Chemical Kinetics

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The catalyzed and uncatalyzed reaction mechanisms of the melt transesterification process of bisphenol‐A and diphenyl carbonate are proposed based on nucleophilic substitution at the carbonyl group of the reactants. The reaction paths and energy barriers of the melt transesterification reaction were predicted and identified via density functional theory (DFT) calculations. The calculations reveal that the different oligomers with only one repeating unit are formed through different thermal processes. The theoretical evaluation further indicates that the basic hydroxide catalysts can reduce the energy barrier for the transesterification reaction, which allows subsequent nucleophilic attack to easily occur. Furthermore, the reaction kinetics of transesterification using tetraethyl ammonium hydroxide as a catalyst were investigated experimentally over a temperature range of 155–175°C. The reaction rate constants and equilibrium constants were determined based on the functional group model, and the equilibrium constants decreased with increasing reaction temperature. A detailed molecular species model with a specific repeating unit (n = 3) was developed and applied to predict the change in the reactants, oligomers, and phenol, and the experimental data and model calculation agree quite well. The standard curves of the oligomer were reversely derived, which provide intuitive insight into the concentration change of each oligomer. Both the DFT calculations and experimental results indicate that the C1 oligomer is first formed, and some of which are then converted to other types or higher molecular weight oligomers.

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Section: Introductionmentioning

confidence: 99%

Reaction Mechanisms and Kinetics of the Melt Transesterification of Bisphenol‐A and Diphenyl Carbonate

Zhao

2018

Int J of Chemical Kinetics

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“…The composi-tions having greater inorganic versus organic amount (inorganic-organic hybrids) are rarely studied. The inorganic-organic hybrid material itself may show interesting and useful physical properties [24][25][26][27]. It also may serve as a precursor to a porous material in which pore diameter and volume may be controlled by the physical volume and the chemical character of incorporated organic phase [28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Low temperature superparamagnetic nanocomposites obtained by Fe(acac)3-SiO2-PVA hybrid xerogel thermolysis

Ianăși

Costişor

Putz

et al. 2016

PAC

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Fe(acac) 3 /silica/PVA hybrid xerogel nanocomposite was obtained by one pot acid catalysed sol-gel synthesis using the homogeneous mixture of iron(III) acetylacetonate (Fe(acac) 3), tetraethylorthosilicate (TEOS), and polyvinyl alcohol (PVA). Nominal composition ratio of iron oxide/silica was 15/85 (weight percent). Nitric acid was used as catalyst. Another sample of Fe(acac) 3 /silica xerogel without PVA addition was prepared in the similar processing conditions. Based on thermal analysis studies, the thermal behaviour of both xerogel samples was unveiled and it allowed choosing the optimal calcination temperatures in order to obtain iron oxide silica magnetic nanocomposite samples. The two xerogel (with and without PVA) samples were thermally treated, in air, at 220, 260 and 300°C and characterized by different techniques. XRD investigations revealed phase composition evolution with calcination temperature, from cubic spinel phase (maghemite) to hexagonal stable hematite containing nanocomposite of 10-20 nm average crystallite size. These findings were confirmed by Mössbauer spectroscopy. Up to 300°C, the surface area and total pores volume increased with temperature for all samples. By calcination at the same temperature, the hybrid xerogel containing PVA resulted in significantly higher magnetization and free volume values in comparison with the sample without PVA.

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Synthesis and Structural Characterization of G-SBA-IDA, G-SBA-EDTA and G-SBA-DTPA Modified Mesoporous SBA-15 Silica and Their Application for Removal of Toxic Metal Ions Pollutants

El‐Nahhal

Chehimi

Selmane

2017

Silicon

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Structural characterization, thermal properties, and density functional theory studies of PMMA‐maghemite hybrid material

Cited by 8 publications

References 29 publications

Reaction Mechanisms and Kinetics of the Melt Transesterification of Bisphenol‐A and Diphenyl Carbonate

Reaction Mechanisms and Kinetics of the Melt Transesterification of Bisphenol‐A and Diphenyl Carbonate

Low temperature superparamagnetic nanocomposites obtained by Fe(acac)3-SiO2-PVA hybrid xerogel thermolysis

Synthesis and Structural Characterization of G-SBA-IDA, G-SBA-EDTA and G-SBA-DTPA Modified Mesoporous SBA-15 Silica and Their Application for Removal of Toxic Metal Ions Pollutants

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