ChemInform Abstract The general preparative route to nido-C2B4 species via reaction of B5H9 with ... more ChemInform Abstract The general preparative route to nido-C2B4 species via reaction of B5H9 with alkynes is applicable to polyalkynes as shown in the scheme for the preparation of (III), (V), and (VII). Even when the B5H9/C≡ C ratio is < 1 all original C≡ C nits are converted to nido-carborane cages; no partially converted products are found. The open-chain carborane oligomers undergo bridge-deprotonation by NaH and further Fe2+-assisted oxidative fusion to give multicage products containing C4B8 cages, but only ntermolecularly. The cyclic bis(carboranes) can be deprotonated but do not undergo metal-promoted oxidative fusion. All products are characterized by IR, electronic, 1H, 11B, 13C NMR, and mass spectra.
... POLYMERIC MATERIALS CONSTRUCTED FROM METALLOPHTHALOCYANINES TAMOTSU INABEla, JOSEPH F. LOMAXl... more ... POLYMERIC MATERIALS CONSTRUCTED FROM METALLOPHTHALOCYANINES TAMOTSU INABEla, JOSEPH F. LOMAXla, JOSEPH W. LYDINGlb ... WJ Pietro, TJ Marks and MA Ratner, Mol. Cryst. Liq. ... PJ Nigrey, D. MacInnes, Jr., DP Nairns, AG MacDiarmid and AJ Heeger, J ...
Additional file 1. The FTIR spectra of reaction products of Naphthol AS-G with five substituted a... more Additional file 1. The FTIR spectra of reaction products of Naphthol AS-G with five substituted anilines (2,5-di-chloro, 2,4-di-nitro, 4-methoxy, 3-cyano, 4-trifluoromethyl).
ART CONSERVATION CHEMISTRY LABORATORY PROJECTS (Joseph F. Lomax coordinator) Conservation Chemist... more ART CONSERVATION CHEMISTRY LABORATORY PROJECTS (Joseph F. Lomax coordinator) Conservation Chemistry is a field of chemistry that deals with the challenges inherent in the preservation of art and artifacts. By its very nature it deals with time; it deals with items from the past in the present for the future. So in a sense, conservation chemistry is chemistry fully in four dimensions. Though impacted by all fields of chemistry, it is most allied to materials and analytical chemistry. Along with my collaborator, Dr. Suzanne Q. Lomax of the National Gallery of Art, I intend to write a book on Conservation Chemistry. It will be a 200-level general science course (prerequisite: general chemistry) with a lab component. The labs will include creation of artist materials such as paint, investigation into restoration techniques and use of one or more of a wide range of analytical techniques such as IR, Raman, NMR and X-Ray Fluorescence spectroscopies, as well as GC-MS and powder X-ray diffra...
Illustrating Bronsted-Lowry acids / bases and redox reactions by involving student movement and i... more Illustrating Bronsted-Lowry acids / bases and redox reactions by involving student movement and interaction.
Using the electron-hopping model (analogous to people sitting in chairs) to explain electron move... more Using the electron-hopping model (analogous to people sitting in chairs) to explain electron movement and conductivity in insulators, semiconductors, and metals.
ABSTRACT Nanocomposites composed of poly(carbonate) (PC) and oxide nanoparticles have been studie... more ABSTRACT Nanocomposites composed of poly(carbonate) (PC) and oxide nanoparticles have been studied. For BaTiO3 both as-received and surface-treated (3-aminopropyl-trimethoxysilane) nanoparticles were utilized. The complex relative permittivity, ɛ*= ɛ&#39;-jɛ&#39;&#39;, at audio frequencies from 5K to about 500K and the room temperature breakdown strength have been determined. Also, SEM, DSC and TGA studies have been carried out. ɛ&#39; is 11 for PC containing 59 wt-% of untreated 50-70 nm diameter BaTiO3 and ɛ&#39; vs. nanoparticle content is larger than would be expected on the basis of the modified Hanai equation. Also, the breakdown strength is low and decreases as nanoparticle content increases. However, ɛ&#39; is low and the breakdown strength is high for PC containing the surface-treated nanoparticles. The gamma relaxation (200K and 1000 Hz) does not change as nanoparticle content increases to 59 wt-%. Also, a low temperature relaxation region (in the vicinity of 20K) associated with the nanoparticles is found in the nanocomposites. Next, the breakdown strength increases as BaTiO3nanoparticle size increases from 50 nm to 500 nm.
for 11 GeoRaman International Conference, June 15-19, 2014, St. Louis, Missourri, USA The Examina... more for 11 GeoRaman International Conference, June 15-19, 2014, St. Louis, Missourri, USA The Examination of Synthetic Organic Pigments in Modern Works of Art by Raman Microscopy and Laser Desorption Ionziation Mass Spectrometry S. Q. Lomax, J. F. Lomax, and A. De-Luca Westrate, National Gallery of Art, DCL-SR, 2000B South Club Drive, Landover MD 20785, USA, [email protected]; Chemistry Department, United States Naval Academy 572M Holloway Road, Annapolis MD 21402, USA, [email protected]. Abstract: Synthetic organic pigments are laboratorySynthetic organic pigments are laboratorymade pigments used in many fields, including the coloration of industrial and architectural paints, textiles, plastics, and printing inks as well as artists’ materials. They are widely used in modern and contemporary works of art, especially to approximate hues normally achieved with mineral pigments now deemed toxic. Identification of these pigments can help to inform conservation treatment and display decisions as ...
This work reports data on the preparation and properties of cast films of BaTiO3 nanoparticles (h... more This work reports data on the preparation and properties of cast films of BaTiO3 nanoparticles (high dielectric constant) in the polyetherimide, Ultem® 1000. Ultem has good mechanical properties and a high glass transition temperature, Tg (217o C), but a low dielectric constant of about 3.1 (room temperature and pressure and audio frequencies) [1,2]. A series of cast films was prepared with up to 69% by mass BaTiO3 (0.33 volume fraction). Electrical and thermal properties implied good dispersion of the BaTiO3. The real part of the dielectric constant of the films is reported and compared with predictions from theories of mixtures of materials [3,4]. In a recently published equation [3], the dielectric constant of a composite is related to the dielectric constants of the components and the volume fraction of the the components using an empirical constant, . The data reported here fit well when μ = 3.34, in contrast to the original Hanai equation [4] (μ = 3) which underestimates the ...
ABSTRACT β’’-aluminas substituted with rare-earth elements (Pr, Nd, Er, and Tb) and Sn have been ... more ABSTRACT β’’-aluminas substituted with rare-earth elements (Pr, Nd, Er, and Tb) and Sn have been studied using near-edge and extended x-ray-absorption fine structure (NEXAFS and EXAFS). In addition, dielectric-relaxation (DR) measurements have been made on Na–β-, Na–β’’-, and Na-Er–β’’-alumina. Both the DR and EXAFS results confirm that disorder, particularly in the conduction plane, in the vicinity of the rare-earth ions is a key feature of the β’’-aluminas. The NEXAFS studies show that the rare-earth ions are ionized to trivalency and are highly localized; in contrast, Sn is clearly divalent, as in SnO.
The relative permittivity has been measured at audio frequencies and low temperatures for nanocom... more The relative permittivity has been measured at audio frequencies and low temperatures for nanocomposites composed of poly(ether imide) (PEI) and BaTiO3 nanoparticles, the nanoparticles in a cavity and polycrystalline BaTiO3. The data at room temperature, for the real part of the relative permittivity versus nanoparticle content of the heat-treated nanocomposites, are found to follow a recently proposed modified Hanai equation.
ABSTRACT The real part of the relative permittivity, ε′, and dielectric loss, tan δ, have been de... more ABSTRACT The real part of the relative permittivity, ε′, and dielectric loss, tan δ, have been determined at audio frequencies at temperatures from about 5 K to 350 K for nano-composites composed of BaTiO3 nanoparticles and polycarbonate. The room temperature breakdown strength was also measured and thermal analysis, nuclear magnetic resonance and scanning electron microscopy studies were carried out. For some films the nanoparticles were surface-treated (STNP) while for others they were not (UNP). For concentrations of UNP greater than about 3.4 vol. %, ε′ is much larger than expected on the basis of laws of mixing. On the other hand, ε′ for materials made using STNP is well-behaved. Correspondingly, increased loss (ε″ or tan δ) in the vicinity of room temperature is observed for the materials made from UNP. The anomalously large values of relative permittivity and increased loss are attributed to the presence of large aggregates in the materials made using the UNP. For both UNP-and STNP-based materials, the breakdown strength is found to decrease as nanoparticle concentration increases. The breakdown strength for the materials made using STNP is found to be larger for all concentrations than for those containing UNP despite the presence of large aggregates in some of the STNP-based materials. This shows that breakdown is strongly affected by the nanoparticle surfaces and/or the interface layer. It is also found that the breakdown strength for materials made using UNP increases as particle size increases. Finally, variable temperature and pressure proton nuclear magnetic resonance relaxation measurements were made to assess the effect of nanoparticle inclusion on polymer motion, and the effects were found to be very minor.
A dielectric study of the water peak in glassy polyetherimide is reported. The peak is found to s... more A dielectric study of the water peak in glassy polyetherimide is reported. The peak is found to shift to higher frequency with increasing intensity (associated with increasing water content) and to shift to lower frequency with increasing pressure. The temperature dependence of the peak position is Arrhenius with activation energy 0.46 eV. The activation volume is approximately equal to the Van der Waals b coefficient which is about twice the volume of a water molecule. This implies that the relaxation mechanism involves more than simple reorientation of a water molecule. Modeling results suggest that water molecules can associate with the glassy polymer through hydrogen bonds to the imide carbonyl oxygen atoms. In the case of Ultem Ò 1000, a water molecule is able to H-bond simultaneously with two carbonyl oxygens, however in Ultem Ò 5000 the para-bisimide linkage leads to improved chain packing and the more extended geometry allows only one H-bond between each imide carbonyl unit and water molecule.
ChemInform Abstract The general preparative route to nido-C2B4 species via reaction of B5H9 with ... more ChemInform Abstract The general preparative route to nido-C2B4 species via reaction of B5H9 with alkynes is applicable to polyalkynes as shown in the scheme for the preparation of (III), (V), and (VII). Even when the B5H9/C≡ C ratio is < 1 all original C≡ C nits are converted to nido-carborane cages; no partially converted products are found. The open-chain carborane oligomers undergo bridge-deprotonation by NaH and further Fe2+-assisted oxidative fusion to give multicage products containing C4B8 cages, but only ntermolecularly. The cyclic bis(carboranes) can be deprotonated but do not undergo metal-promoted oxidative fusion. All products are characterized by IR, electronic, 1H, 11B, 13C NMR, and mass spectra.
... POLYMERIC MATERIALS CONSTRUCTED FROM METALLOPHTHALOCYANINES TAMOTSU INABEla, JOSEPH F. LOMAXl... more ... POLYMERIC MATERIALS CONSTRUCTED FROM METALLOPHTHALOCYANINES TAMOTSU INABEla, JOSEPH F. LOMAXla, JOSEPH W. LYDINGlb ... WJ Pietro, TJ Marks and MA Ratner, Mol. Cryst. Liq. ... PJ Nigrey, D. MacInnes, Jr., DP Nairns, AG MacDiarmid and AJ Heeger, J ...
Additional file 1. The FTIR spectra of reaction products of Naphthol AS-G with five substituted a... more Additional file 1. The FTIR spectra of reaction products of Naphthol AS-G with five substituted anilines (2,5-di-chloro, 2,4-di-nitro, 4-methoxy, 3-cyano, 4-trifluoromethyl).
ART CONSERVATION CHEMISTRY LABORATORY PROJECTS (Joseph F. Lomax coordinator) Conservation Chemist... more ART CONSERVATION CHEMISTRY LABORATORY PROJECTS (Joseph F. Lomax coordinator) Conservation Chemistry is a field of chemistry that deals with the challenges inherent in the preservation of art and artifacts. By its very nature it deals with time; it deals with items from the past in the present for the future. So in a sense, conservation chemistry is chemistry fully in four dimensions. Though impacted by all fields of chemistry, it is most allied to materials and analytical chemistry. Along with my collaborator, Dr. Suzanne Q. Lomax of the National Gallery of Art, I intend to write a book on Conservation Chemistry. It will be a 200-level general science course (prerequisite: general chemistry) with a lab component. The labs will include creation of artist materials such as paint, investigation into restoration techniques and use of one or more of a wide range of analytical techniques such as IR, Raman, NMR and X-Ray Fluorescence spectroscopies, as well as GC-MS and powder X-ray diffra...
Illustrating Bronsted-Lowry acids / bases and redox reactions by involving student movement and i... more Illustrating Bronsted-Lowry acids / bases and redox reactions by involving student movement and interaction.
Using the electron-hopping model (analogous to people sitting in chairs) to explain electron move... more Using the electron-hopping model (analogous to people sitting in chairs) to explain electron movement and conductivity in insulators, semiconductors, and metals.
ABSTRACT Nanocomposites composed of poly(carbonate) (PC) and oxide nanoparticles have been studie... more ABSTRACT Nanocomposites composed of poly(carbonate) (PC) and oxide nanoparticles have been studied. For BaTiO3 both as-received and surface-treated (3-aminopropyl-trimethoxysilane) nanoparticles were utilized. The complex relative permittivity, ɛ*= ɛ&#39;-jɛ&#39;&#39;, at audio frequencies from 5K to about 500K and the room temperature breakdown strength have been determined. Also, SEM, DSC and TGA studies have been carried out. ɛ&#39; is 11 for PC containing 59 wt-% of untreated 50-70 nm diameter BaTiO3 and ɛ&#39; vs. nanoparticle content is larger than would be expected on the basis of the modified Hanai equation. Also, the breakdown strength is low and decreases as nanoparticle content increases. However, ɛ&#39; is low and the breakdown strength is high for PC containing the surface-treated nanoparticles. The gamma relaxation (200K and 1000 Hz) does not change as nanoparticle content increases to 59 wt-%. Also, a low temperature relaxation region (in the vicinity of 20K) associated with the nanoparticles is found in the nanocomposites. Next, the breakdown strength increases as BaTiO3nanoparticle size increases from 50 nm to 500 nm.
for 11 GeoRaman International Conference, June 15-19, 2014, St. Louis, Missourri, USA The Examina... more for 11 GeoRaman International Conference, June 15-19, 2014, St. Louis, Missourri, USA The Examination of Synthetic Organic Pigments in Modern Works of Art by Raman Microscopy and Laser Desorption Ionziation Mass Spectrometry S. Q. Lomax, J. F. Lomax, and A. De-Luca Westrate, National Gallery of Art, DCL-SR, 2000B South Club Drive, Landover MD 20785, USA, [email protected]; Chemistry Department, United States Naval Academy 572M Holloway Road, Annapolis MD 21402, USA, [email protected]. Abstract: Synthetic organic pigments are laboratorySynthetic organic pigments are laboratorymade pigments used in many fields, including the coloration of industrial and architectural paints, textiles, plastics, and printing inks as well as artists’ materials. They are widely used in modern and contemporary works of art, especially to approximate hues normally achieved with mineral pigments now deemed toxic. Identification of these pigments can help to inform conservation treatment and display decisions as ...
This work reports data on the preparation and properties of cast films of BaTiO3 nanoparticles (h... more This work reports data on the preparation and properties of cast films of BaTiO3 nanoparticles (high dielectric constant) in the polyetherimide, Ultem® 1000. Ultem has good mechanical properties and a high glass transition temperature, Tg (217o C), but a low dielectric constant of about 3.1 (room temperature and pressure and audio frequencies) [1,2]. A series of cast films was prepared with up to 69% by mass BaTiO3 (0.33 volume fraction). Electrical and thermal properties implied good dispersion of the BaTiO3. The real part of the dielectric constant of the films is reported and compared with predictions from theories of mixtures of materials [3,4]. In a recently published equation [3], the dielectric constant of a composite is related to the dielectric constants of the components and the volume fraction of the the components using an empirical constant, . The data reported here fit well when μ = 3.34, in contrast to the original Hanai equation [4] (μ = 3) which underestimates the ...
ABSTRACT β’’-aluminas substituted with rare-earth elements (Pr, Nd, Er, and Tb) and Sn have been ... more ABSTRACT β’’-aluminas substituted with rare-earth elements (Pr, Nd, Er, and Tb) and Sn have been studied using near-edge and extended x-ray-absorption fine structure (NEXAFS and EXAFS). In addition, dielectric-relaxation (DR) measurements have been made on Na–β-, Na–β’’-, and Na-Er–β’’-alumina. Both the DR and EXAFS results confirm that disorder, particularly in the conduction plane, in the vicinity of the rare-earth ions is a key feature of the β’’-aluminas. The NEXAFS studies show that the rare-earth ions are ionized to trivalency and are highly localized; in contrast, Sn is clearly divalent, as in SnO.
The relative permittivity has been measured at audio frequencies and low temperatures for nanocom... more The relative permittivity has been measured at audio frequencies and low temperatures for nanocomposites composed of poly(ether imide) (PEI) and BaTiO3 nanoparticles, the nanoparticles in a cavity and polycrystalline BaTiO3. The data at room temperature, for the real part of the relative permittivity versus nanoparticle content of the heat-treated nanocomposites, are found to follow a recently proposed modified Hanai equation.
ABSTRACT The real part of the relative permittivity, ε′, and dielectric loss, tan δ, have been de... more ABSTRACT The real part of the relative permittivity, ε′, and dielectric loss, tan δ, have been determined at audio frequencies at temperatures from about 5 K to 350 K for nano-composites composed of BaTiO3 nanoparticles and polycarbonate. The room temperature breakdown strength was also measured and thermal analysis, nuclear magnetic resonance and scanning electron microscopy studies were carried out. For some films the nanoparticles were surface-treated (STNP) while for others they were not (UNP). For concentrations of UNP greater than about 3.4 vol. %, ε′ is much larger than expected on the basis of laws of mixing. On the other hand, ε′ for materials made using STNP is well-behaved. Correspondingly, increased loss (ε″ or tan δ) in the vicinity of room temperature is observed for the materials made from UNP. The anomalously large values of relative permittivity and increased loss are attributed to the presence of large aggregates in the materials made using the UNP. For both UNP-and STNP-based materials, the breakdown strength is found to decrease as nanoparticle concentration increases. The breakdown strength for the materials made using STNP is found to be larger for all concentrations than for those containing UNP despite the presence of large aggregates in some of the STNP-based materials. This shows that breakdown is strongly affected by the nanoparticle surfaces and/or the interface layer. It is also found that the breakdown strength for materials made using UNP increases as particle size increases. Finally, variable temperature and pressure proton nuclear magnetic resonance relaxation measurements were made to assess the effect of nanoparticle inclusion on polymer motion, and the effects were found to be very minor.
A dielectric study of the water peak in glassy polyetherimide is reported. The peak is found to s... more A dielectric study of the water peak in glassy polyetherimide is reported. The peak is found to shift to higher frequency with increasing intensity (associated with increasing water content) and to shift to lower frequency with increasing pressure. The temperature dependence of the peak position is Arrhenius with activation energy 0.46 eV. The activation volume is approximately equal to the Van der Waals b coefficient which is about twice the volume of a water molecule. This implies that the relaxation mechanism involves more than simple reorientation of a water molecule. Modeling results suggest that water molecules can associate with the glassy polymer through hydrogen bonds to the imide carbonyl oxygen atoms. In the case of Ultem Ò 1000, a water molecule is able to H-bond simultaneously with two carbonyl oxygens, however in Ultem Ò 5000 the para-bisimide linkage leads to improved chain packing and the more extended geometry allows only one H-bond between each imide carbonyl unit and water molecule.
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