The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Dong Hack Suh - One of the best experts on this subject based on the ideXlab platform.
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high thermal stability of bio based polycarbonates containing Cyclic Ketal moieties
Macromolecules, 2015Co-Authors: Gwangho Choi, Da Young Hwang, Dong Hack SuhAbstract:Bio-based polycarbonates containing Cyclic Ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (abbreviated as CaG) was analyzed by 1H, 13C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (Mw = 18 652) abbreviated as PCaGC and for copolycarbonate (Mw = 78 482) as PCaG20BPA80C. The high thermal stability (Td value above 350 °C) and glass transition temperature (Tg value from 128 to 151 °C) of PCaGCs and PCaGxBPAyCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers.
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High Thermal Stability of Bio-Based Polycarbonates Containing Cyclic Ketal Moieties
2015Co-Authors: Gwangho Choi, Da Young Hwang, Dong Hack SuhAbstract:Bio-based polycarbonates containing Cyclic Ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (abbreviated as CaG) was analyzed by 1H, 13C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (Mw = 18 652) abbreviated as PCaGC and for copolycarbonate (Mw = 78 482) as PCaG20BPA80C. The high thermal stability (Td value above 350 °C) and glass transition temperature (Tg value from 128 to 151 °C) of PCaGCs and PCaGxBPAyCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers
Volker S Urban - One of the best experts on this subject based on the ideXlab platform.
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physicochemical characterization of water in oil microemulsions formed by a binary 1 3 dioxolane alkyl ethoxylate aerosol ot surfactant system
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013Co-Authors: Douglas G Hayes, Mayson H Alkhatib, Javier Gomez A Del Rio, Volker S UrbanAbstract:Abstract The physicochemical behavior of the binary surfactant system consisting of the ionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate, or Aerosol-OT (AOT), and the two-tailed Cyclic Ketal alkyl ethoxylate (2-tridecyl, 2-ethyl-1,3-dioxolan-4-yl) methoxy]- O ′-methoxy poly(ethylene glycol)], or CK-2,13, in water/isooctane water-in-oil (w/o-) microemulsion systems enriched in AOT was performed to understand the arrangement of the two surfactants at the interface and the behavior and properties of the microemulsion systems to enable applications. Many of the properties observed were similar to microemulsions formed by AOT/C 12 E 4 or C 12 E 5 , the latter two being linear alkyl ethoxylates of comparable tail length and average ethoxylate size, including a decrease of water solubilization and increase of attractive interactions with an increase of ethoxylate surfactant concentration, the latter determined via small-angle neutron scattering (SANS). SANS also demonstrated that the increase of the CK-2,13 fraction among the surfactants from 0.1 to 0.2 to 0.3 induced a change in shape from spheres to ellipsoids to cylinders, a trend not reported for AOT/C i E j binary mixtures, and that the surface area per CK-2,13 molecule was approximately 35 A 2 , nearly identical to the value reported for C 12 E 5 . Profiles of electrical conductivity versus the water-surfactant mole ratio ( W 0 ) for microemulsions prepared at low surfactant concentrations (far below the percolation threshold) were bell-shaped, consistent with the charge-fluctuation model, and shifted to lower W 0 as the alkyl ethoxylate fraction was increased. The extent of the shift was greater for CK-2,13 than for an equal proportion of C 12 E 4 , suggesting CK-2,13 possesses a more profound influence on microemulsion properties. Analysis of the OH stretching region (3100–3700 cm −1 ) of the Fourier Transform Infrared Spectroscopic spectrum for w/o-microemulsions demonstrated that an increase of the CK-2,13 content of the total surfactant led to an increase of water molecules localized near the Na + counterion of AOT of 0.7 mol water per mol surfactant, suggesting the water molecules of hydration for the ethoxylate group reside near AOT's counterion, resulting in increased dissociation of the counterion, hence to an increased hydrophilicity for AOT.
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characterization of microemulsion systems formed by a mixed 1 3 dioxolane ethoxylate octyl glucoside surfactant system
Journal of Surfactants and Detergents, 2009Co-Authors: Mayson H Alkhatib, Douglas G Hayes, Volker S UrbanAbstract:The phase behavior of microemulsion systems containing water (or 1.0 wt% NaClaq), isooctane, and the binary surfactant system consisting of n-octyl-β-d-glucopyranoside, C8βG1, and the acid-cleavable alkyl ethoxylate, 4-CH3O (CH2CH2O)7.2, 2-(CH2)12CH3, 2-(CH2)CH3, 1,3-dioxolane, or “Cyclic Ketal” (“CK-2,13”), was determined. Large temperature-insensitive one, two, and three-phase microemulsion-phase regions were obtained when equal masses of the two surfactants were employed, suggesting that C8βG1 reduces the temperature sensitivity of CK-2,13’s ethoxylate group. Addition of C8βG1 to CK-2,13 greatly improves the latter’s low efficiency, evidenced by the formation of a three-phase microemulsion system for surfactant concentrations at low fractions of total surfactants for systems with equal mass ratios of water to oil and CK-2,13 to C8βG1. Analysis of the phase diagrams also suggests that CK-2,13 and C8βG1 impart hydrophobic and hydrophilic character, respectively, to the surfactant mixture, and that addition of salt further increases the hydrophilicity of C8βG1, presumably because of the salting-in of the latter. Analysis of small-angle neutron scattering data revealed that the mixed surfactant system formed spherical oil-in-water microemulsions, and that increasing the CK-2,13 fraction among the surfactants reduced the critical microemulsion concentration but slightly increased the nanodroplet size.
Gwangho Choi - One of the best experts on this subject based on the ideXlab platform.
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high thermal stability of bio based polycarbonates containing Cyclic Ketal moieties
Macromolecules, 2015Co-Authors: Gwangho Choi, Da Young Hwang, Dong Hack SuhAbstract:Bio-based polycarbonates containing Cyclic Ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (abbreviated as CaG) was analyzed by 1H, 13C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (Mw = 18 652) abbreviated as PCaGC and for copolycarbonate (Mw = 78 482) as PCaG20BPA80C. The high thermal stability (Td value above 350 °C) and glass transition temperature (Tg value from 128 to 151 °C) of PCaGCs and PCaGxBPAyCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers.
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High Thermal Stability of Bio-Based Polycarbonates Containing Cyclic Ketal Moieties
2015Co-Authors: Gwangho Choi, Da Young Hwang, Dong Hack SuhAbstract:Bio-based polycarbonates containing Cyclic Ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (abbreviated as CaG) was analyzed by 1H, 13C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (Mw = 18 652) abbreviated as PCaGC and for copolycarbonate (Mw = 78 482) as PCaG20BPA80C. The high thermal stability (Td value above 350 °C) and glass transition temperature (Tg value from 128 to 151 °C) of PCaGCs and PCaGxBPAyCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers
Douglas G Hayes - One of the best experts on this subject based on the ideXlab platform.
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physicochemical characterization of water in oil microemulsions formed by a binary 1 3 dioxolane alkyl ethoxylate aerosol ot surfactant system
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013Co-Authors: Douglas G Hayes, Mayson H Alkhatib, Javier Gomez A Del Rio, Volker S UrbanAbstract:Abstract The physicochemical behavior of the binary surfactant system consisting of the ionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate, or Aerosol-OT (AOT), and the two-tailed Cyclic Ketal alkyl ethoxylate (2-tridecyl, 2-ethyl-1,3-dioxolan-4-yl) methoxy]- O ′-methoxy poly(ethylene glycol)], or CK-2,13, in water/isooctane water-in-oil (w/o-) microemulsion systems enriched in AOT was performed to understand the arrangement of the two surfactants at the interface and the behavior and properties of the microemulsion systems to enable applications. Many of the properties observed were similar to microemulsions formed by AOT/C 12 E 4 or C 12 E 5 , the latter two being linear alkyl ethoxylates of comparable tail length and average ethoxylate size, including a decrease of water solubilization and increase of attractive interactions with an increase of ethoxylate surfactant concentration, the latter determined via small-angle neutron scattering (SANS). SANS also demonstrated that the increase of the CK-2,13 fraction among the surfactants from 0.1 to 0.2 to 0.3 induced a change in shape from spheres to ellipsoids to cylinders, a trend not reported for AOT/C i E j binary mixtures, and that the surface area per CK-2,13 molecule was approximately 35 A 2 , nearly identical to the value reported for C 12 E 5 . Profiles of electrical conductivity versus the water-surfactant mole ratio ( W 0 ) for microemulsions prepared at low surfactant concentrations (far below the percolation threshold) were bell-shaped, consistent with the charge-fluctuation model, and shifted to lower W 0 as the alkyl ethoxylate fraction was increased. The extent of the shift was greater for CK-2,13 than for an equal proportion of C 12 E 4 , suggesting CK-2,13 possesses a more profound influence on microemulsion properties. Analysis of the OH stretching region (3100–3700 cm −1 ) of the Fourier Transform Infrared Spectroscopic spectrum for w/o-microemulsions demonstrated that an increase of the CK-2,13 content of the total surfactant led to an increase of water molecules localized near the Na + counterion of AOT of 0.7 mol water per mol surfactant, suggesting the water molecules of hydration for the ethoxylate group reside near AOT's counterion, resulting in increased dissociation of the counterion, hence to an increased hydrophilicity for AOT.
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characterization of microemulsion systems formed by a mixed 1 3 dioxolane ethoxylate octyl glucoside surfactant system
Journal of Surfactants and Detergents, 2009Co-Authors: Mayson H Alkhatib, Douglas G Hayes, Volker S UrbanAbstract:The phase behavior of microemulsion systems containing water (or 1.0 wt% NaClaq), isooctane, and the binary surfactant system consisting of n-octyl-β-d-glucopyranoside, C8βG1, and the acid-cleavable alkyl ethoxylate, 4-CH3O (CH2CH2O)7.2, 2-(CH2)12CH3, 2-(CH2)CH3, 1,3-dioxolane, or “Cyclic Ketal” (“CK-2,13”), was determined. Large temperature-insensitive one, two, and three-phase microemulsion-phase regions were obtained when equal masses of the two surfactants were employed, suggesting that C8βG1 reduces the temperature sensitivity of CK-2,13’s ethoxylate group. Addition of C8βG1 to CK-2,13 greatly improves the latter’s low efficiency, evidenced by the formation of a three-phase microemulsion system for surfactant concentrations at low fractions of total surfactants for systems with equal mass ratios of water to oil and CK-2,13 to C8βG1. Analysis of the phase diagrams also suggests that CK-2,13 and C8βG1 impart hydrophobic and hydrophilic character, respectively, to the surfactant mixture, and that addition of salt further increases the hydrophilicity of C8βG1, presumably because of the salting-in of the latter. Analysis of small-angle neutron scattering data revealed that the mixed surfactant system formed spherical oil-in-water microemulsions, and that increasing the CK-2,13 fraction among the surfactants reduced the critical microemulsion concentration but slightly increased the nanodroplet size.
Da Young Hwang - One of the best experts on this subject based on the ideXlab platform.
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high thermal stability of bio based polycarbonates containing Cyclic Ketal moieties
Macromolecules, 2015Co-Authors: Gwangho Choi, Da Young Hwang, Dong Hack SuhAbstract:Bio-based polycarbonates containing Cyclic Ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (abbreviated as CaG) was analyzed by 1H, 13C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (Mw = 18 652) abbreviated as PCaGC and for copolycarbonate (Mw = 78 482) as PCaG20BPA80C. The high thermal stability (Td value above 350 °C) and glass transition temperature (Tg value from 128 to 151 °C) of PCaGCs and PCaGxBPAyCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers.
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High Thermal Stability of Bio-Based Polycarbonates Containing Cyclic Ketal Moieties
2015Co-Authors: Gwangho Choi, Da Young Hwang, Dong Hack SuhAbstract:Bio-based polycarbonates containing Cyclic Ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (abbreviated as CaG) was analyzed by 1H, 13C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (Mw = 18 652) abbreviated as PCaGC and for copolycarbonate (Mw = 78 482) as PCaG20BPA80C. The high thermal stability (Td value above 350 °C) and glass transition temperature (Tg value from 128 to 151 °C) of PCaGCs and PCaGxBPAyCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers
