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Steven P Armes - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Vinyl Polymer silica colloidal nanocomposites prepared using commercial alcoholic silica sols
Langmuir, 2004Co-Authors: M J Percy, Steven P Armes, S J Greaves, J I Amalvy, David P Randall, John F WattsAbstract:The surfactant-free synthesis of Vinyl Polymer−silica nanocomposite particles has been achieved in aqueous alcoholic media at ambient temperature in the absence of auxiliary comonomers. Styrene, methyl methacrylate, methyl acrylate, n-butyl acrylate, and 2-hydroxypropyl methacrylate were homoPolymerized in turn in the presence of three commercially available ultrafine alcoholic silica sols. Stable colloidal dispersions with reasonably narrow size distributions were obtained, with silica contents of up to 58% by mass indicated by thermogravimetric analysis. Particle size distributions were assessed using both dynamic light scattering and disk centrifuge photosedimentometry. The former technique indicated that the particle size increased for the first 1−2 h at 25 °C and thereafter remained constant. Particle morphologies were studied using electron microscopy. Most of the colloidal nanocomposites comprised approximately spherical particles with relatively narrow size distributions, but in some cases more po...
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synthesis of Vinyl Polymer silica colloidal nanocomposites via aqueous dispersion Polymerization
Langmuir, 2003Co-Authors: M J Percy, V Michailidou, Steven P Armes, Christian Perruchot, John F Watts, S J GreavesAbstract:The surfactant-free synthesis of colloidal dispersions of Vinyl Polymer−silica nanocomposite particles in aqueous media using a batch emulsion Polymerization protocol has been previously described [Percy, M. J.; et al. Langmuir 2000, 16, 6913]. In the present work 2-hydroxypropyl methacrylate [HPMA] was coPolymerized with 4-Vinylpyridine [4VP] using ammonium persulfate in the presence of an ultrafine silica sol. 4VP is used as an auxiliary in these syntheses; the strong interaction of this basic monomer with the acidic surface of the silica particles is essential for successful nanocomposite particle formation. HPMA monomer was selected since it has appreciable water solubility (up to 13% at 20 °C), but HPMA homoPolymer is water-insoluble. This unusual solubility behavior ensured that these nanocomposite syntheses were conducted under true dispersion Polymerization conditions. In view of the success of these syntheses, we conclude that emulsion monomer droplets and micelles are not a prerequisite for the ...
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synthesis and characterization of novel film forming Vinyl Polymer silica colloidal nanocomposites
Langmuir, 2001Co-Authors: J I Amalvy, Steven P Armes, And M J Percy, H WieseAbstract:We report the surfactant-free synthesis of new, film-forming Vinyl Polymer/silica colloidal nanocomposites by coPolymerization of 4-Vinylpyridine (4VP) with either n-butyl acrylate (n-BuA) or n-butyl methacrylate (n-BuMA) in the presence of an ultrafine aqueous silica sol. Highly transparent, free-standing nanocomposite films were readily obtained by solution-casting from aqueous media at room temperature. Thermogravimetric analyses indicated silica contents ranging from 20% to 56%, depending on the nanocomposite formulation, and intensity-average particle diameters ranged from 139 to 305 nm. The influence of the synthesis conditions on the particle properties was also studied. Reducing the initial silica concentration at constant monomer concentration led to an increase in the particle size and reduced colloid stability, indicating that the ultrafine silica sol stabilized the colloidal nanocomposites. Colloidal nanocomposites were also prepared using a methacrylate-capped poly(ethylene glycol) (MPEGMA) m...
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synthesis and characterization of Vinyl Polymer silica colloidal nanocomposites
Langmuir, 2000Co-Authors: M J Percy, C Barthet, J C Lobb, Mubarak Ali Khan, Stuart F Lascelles, Maria Vamvakaki, Steven P ArmesAbstract:Colloidal dispersions of Polymer−silica nanocomposite particles were synthesized in high yield by homoPolymerizing 4-Vinylpyridine (4VP) in the presence of an ultrafine silica sol using a free-radical initiator in aqueous media at 60 °C. CoPolymerization of 4VP with methyl methacrylate and styrene also produced colloidally stable nanocomposite particles, in some cases for comonomer feeds containing as little as 6 mol % 4VP. However, homoPolymerization of styrene or methyl methacrylate in the presence of the silica sol did not produce nanocomposite particles in control experiments. Thus a strong acid−base interaction between the silica sol and the (co)Polymer appears to be essential for nanocomposite formation. Transmission electron microscopy studies confirmed the presence of the ultrafine silica sols within the nanocomposite particles, which typically exhibited “currant-bun” particle morphologies. This is in contrast to the “raspberry” particle morphologies previously reported for conducting Polymer−sili...
M J Percy - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Vinyl Polymer silica colloidal nanocomposites prepared using commercial alcoholic silica sols
Langmuir, 2004Co-Authors: M J Percy, Steven P Armes, S J Greaves, J I Amalvy, David P Randall, John F WattsAbstract:The surfactant-free synthesis of Vinyl Polymer−silica nanocomposite particles has been achieved in aqueous alcoholic media at ambient temperature in the absence of auxiliary comonomers. Styrene, methyl methacrylate, methyl acrylate, n-butyl acrylate, and 2-hydroxypropyl methacrylate were homoPolymerized in turn in the presence of three commercially available ultrafine alcoholic silica sols. Stable colloidal dispersions with reasonably narrow size distributions were obtained, with silica contents of up to 58% by mass indicated by thermogravimetric analysis. Particle size distributions were assessed using both dynamic light scattering and disk centrifuge photosedimentometry. The former technique indicated that the particle size increased for the first 1−2 h at 25 °C and thereafter remained constant. Particle morphologies were studied using electron microscopy. Most of the colloidal nanocomposites comprised approximately spherical particles with relatively narrow size distributions, but in some cases more po...
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synthesis of Vinyl Polymer silica colloidal nanocomposites via aqueous dispersion Polymerization
Langmuir, 2003Co-Authors: M J Percy, V Michailidou, Steven P Armes, Christian Perruchot, John F Watts, S J GreavesAbstract:The surfactant-free synthesis of colloidal dispersions of Vinyl Polymer−silica nanocomposite particles in aqueous media using a batch emulsion Polymerization protocol has been previously described [Percy, M. J.; et al. Langmuir 2000, 16, 6913]. In the present work 2-hydroxypropyl methacrylate [HPMA] was coPolymerized with 4-Vinylpyridine [4VP] using ammonium persulfate in the presence of an ultrafine silica sol. 4VP is used as an auxiliary in these syntheses; the strong interaction of this basic monomer with the acidic surface of the silica particles is essential for successful nanocomposite particle formation. HPMA monomer was selected since it has appreciable water solubility (up to 13% at 20 °C), but HPMA homoPolymer is water-insoluble. This unusual solubility behavior ensured that these nanocomposite syntheses were conducted under true dispersion Polymerization conditions. In view of the success of these syntheses, we conclude that emulsion monomer droplets and micelles are not a prerequisite for the ...
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synthesis and characterization of Vinyl Polymer silica colloidal nanocomposites
Langmuir, 2000Co-Authors: M J Percy, C Barthet, J C Lobb, Mubarak Ali Khan, Stuart F Lascelles, Maria Vamvakaki, Steven P ArmesAbstract:Colloidal dispersions of Polymer−silica nanocomposite particles were synthesized in high yield by homoPolymerizing 4-Vinylpyridine (4VP) in the presence of an ultrafine silica sol using a free-radical initiator in aqueous media at 60 °C. CoPolymerization of 4VP with methyl methacrylate and styrene also produced colloidally stable nanocomposite particles, in some cases for comonomer feeds containing as little as 6 mol % 4VP. However, homoPolymerization of styrene or methyl methacrylate in the presence of the silica sol did not produce nanocomposite particles in control experiments. Thus a strong acid−base interaction between the silica sol and the (co)Polymer appears to be essential for nanocomposite formation. Transmission electron microscopy studies confirmed the presence of the ultrafine silica sols within the nanocomposite particles, which typically exhibited “currant-bun” particle morphologies. This is in contrast to the “raspberry” particle morphologies previously reported for conducting Polymer−sili...
S J Greaves - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Vinyl Polymer silica colloidal nanocomposites prepared using commercial alcoholic silica sols
Langmuir, 2004Co-Authors: M J Percy, Steven P Armes, S J Greaves, J I Amalvy, David P Randall, John F WattsAbstract:The surfactant-free synthesis of Vinyl Polymer−silica nanocomposite particles has been achieved in aqueous alcoholic media at ambient temperature in the absence of auxiliary comonomers. Styrene, methyl methacrylate, methyl acrylate, n-butyl acrylate, and 2-hydroxypropyl methacrylate were homoPolymerized in turn in the presence of three commercially available ultrafine alcoholic silica sols. Stable colloidal dispersions with reasonably narrow size distributions were obtained, with silica contents of up to 58% by mass indicated by thermogravimetric analysis. Particle size distributions were assessed using both dynamic light scattering and disk centrifuge photosedimentometry. The former technique indicated that the particle size increased for the first 1−2 h at 25 °C and thereafter remained constant. Particle morphologies were studied using electron microscopy. Most of the colloidal nanocomposites comprised approximately spherical particles with relatively narrow size distributions, but in some cases more po...
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synthesis of Vinyl Polymer silica colloidal nanocomposites via aqueous dispersion Polymerization
Langmuir, 2003Co-Authors: M J Percy, V Michailidou, Steven P Armes, Christian Perruchot, John F Watts, S J GreavesAbstract:The surfactant-free synthesis of colloidal dispersions of Vinyl Polymer−silica nanocomposite particles in aqueous media using a batch emulsion Polymerization protocol has been previously described [Percy, M. J.; et al. Langmuir 2000, 16, 6913]. In the present work 2-hydroxypropyl methacrylate [HPMA] was coPolymerized with 4-Vinylpyridine [4VP] using ammonium persulfate in the presence of an ultrafine silica sol. 4VP is used as an auxiliary in these syntheses; the strong interaction of this basic monomer with the acidic surface of the silica particles is essential for successful nanocomposite particle formation. HPMA monomer was selected since it has appreciable water solubility (up to 13% at 20 °C), but HPMA homoPolymer is water-insoluble. This unusual solubility behavior ensured that these nanocomposite syntheses were conducted under true dispersion Polymerization conditions. In view of the success of these syntheses, we conclude that emulsion monomer droplets and micelles are not a prerequisite for the ...
John F Watts - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Vinyl Polymer silica colloidal nanocomposites prepared using commercial alcoholic silica sols
Langmuir, 2004Co-Authors: M J Percy, Steven P Armes, S J Greaves, J I Amalvy, David P Randall, John F WattsAbstract:The surfactant-free synthesis of Vinyl Polymer−silica nanocomposite particles has been achieved in aqueous alcoholic media at ambient temperature in the absence of auxiliary comonomers. Styrene, methyl methacrylate, methyl acrylate, n-butyl acrylate, and 2-hydroxypropyl methacrylate were homoPolymerized in turn in the presence of three commercially available ultrafine alcoholic silica sols. Stable colloidal dispersions with reasonably narrow size distributions were obtained, with silica contents of up to 58% by mass indicated by thermogravimetric analysis. Particle size distributions were assessed using both dynamic light scattering and disk centrifuge photosedimentometry. The former technique indicated that the particle size increased for the first 1−2 h at 25 °C and thereafter remained constant. Particle morphologies were studied using electron microscopy. Most of the colloidal nanocomposites comprised approximately spherical particles with relatively narrow size distributions, but in some cases more po...
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synthesis of Vinyl Polymer silica colloidal nanocomposites via aqueous dispersion Polymerization
Langmuir, 2003Co-Authors: M J Percy, V Michailidou, Steven P Armes, Christian Perruchot, John F Watts, S J GreavesAbstract:The surfactant-free synthesis of colloidal dispersions of Vinyl Polymer−silica nanocomposite particles in aqueous media using a batch emulsion Polymerization protocol has been previously described [Percy, M. J.; et al. Langmuir 2000, 16, 6913]. In the present work 2-hydroxypropyl methacrylate [HPMA] was coPolymerized with 4-Vinylpyridine [4VP] using ammonium persulfate in the presence of an ultrafine silica sol. 4VP is used as an auxiliary in these syntheses; the strong interaction of this basic monomer with the acidic surface of the silica particles is essential for successful nanocomposite particle formation. HPMA monomer was selected since it has appreciable water solubility (up to 13% at 20 °C), but HPMA homoPolymer is water-insoluble. This unusual solubility behavior ensured that these nanocomposite syntheses were conducted under true dispersion Polymerization conditions. In view of the success of these syntheses, we conclude that emulsion monomer droplets and micelles are not a prerequisite for the ...
J I Amalvy - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Vinyl Polymer silica colloidal nanocomposites prepared using commercial alcoholic silica sols
Langmuir, 2004Co-Authors: M J Percy, Steven P Armes, S J Greaves, J I Amalvy, David P Randall, John F WattsAbstract:The surfactant-free synthesis of Vinyl Polymer−silica nanocomposite particles has been achieved in aqueous alcoholic media at ambient temperature in the absence of auxiliary comonomers. Styrene, methyl methacrylate, methyl acrylate, n-butyl acrylate, and 2-hydroxypropyl methacrylate were homoPolymerized in turn in the presence of three commercially available ultrafine alcoholic silica sols. Stable colloidal dispersions with reasonably narrow size distributions were obtained, with silica contents of up to 58% by mass indicated by thermogravimetric analysis. Particle size distributions were assessed using both dynamic light scattering and disk centrifuge photosedimentometry. The former technique indicated that the particle size increased for the first 1−2 h at 25 °C and thereafter remained constant. Particle morphologies were studied using electron microscopy. Most of the colloidal nanocomposites comprised approximately spherical particles with relatively narrow size distributions, but in some cases more po...
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synthesis and characterization of novel film forming Vinyl Polymer silica colloidal nanocomposites
Langmuir, 2001Co-Authors: J I Amalvy, Steven P Armes, And M J Percy, H WieseAbstract:We report the surfactant-free synthesis of new, film-forming Vinyl Polymer/silica colloidal nanocomposites by coPolymerization of 4-Vinylpyridine (4VP) with either n-butyl acrylate (n-BuA) or n-butyl methacrylate (n-BuMA) in the presence of an ultrafine aqueous silica sol. Highly transparent, free-standing nanocomposite films were readily obtained by solution-casting from aqueous media at room temperature. Thermogravimetric analyses indicated silica contents ranging from 20% to 56%, depending on the nanocomposite formulation, and intensity-average particle diameters ranged from 139 to 305 nm. The influence of the synthesis conditions on the particle properties was also studied. Reducing the initial silica concentration at constant monomer concentration led to an increase in the particle size and reduced colloid stability, indicating that the ultrafine silica sol stabilized the colloidal nanocomposites. Colloidal nanocomposites were also prepared using a methacrylate-capped poly(ethylene glycol) (MPEGMA) m...
