Synthesis of Macroporous PMMA/Silica Nanocomposite Monoliths in Supercritical Carbon Dioxide

Yue, Baohua; Yang, Jun; Huang, Chien-Yueh; Davé, Rajesh N.; Pfeffer, Robert

doi:10.1002/marc.200500239

Cited by 19 publications

(9 citation statements)

References 27 publications

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“…Thus supercritical CO 2 has frequently been employed as a processing solvent to reduce viscosity and to accelerate the mixing of reagents into the polymer. 12 As for polymer-silica nanocomposites, the use of supercritical CO 2 has been studied for macroporous poly(methyl methacrylate)-silica, 13 polypropylene-silica, 14 poly(vinyl acetate)-silica, 15 polystyrenesilica 16 and polypyrrole-silica 17 systems. We have focused on the fact that some Si(OR) 4 species and CO 2 become a homogeneous mixture under high pressure.…”

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confidence: 99%

A porous polymer–silica composite with a “vespula-like” structure for thermal insulating materials prepared via high pressure phase control

et al. 2013

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A new fabrication route for polymer-silica composite foams is developed which includes (1) a homogeneous mixture of polymer, silicon alkoxide, and CO 2 under high pressure and (2) multiple phase separations of the mixture induced by a pressure drop. The method provides a unique "vespula like" porous polymer composite in which the cells include spherical silica-rich microparticles. This is an important milestone for "isolated silica aerogel in a polymer foam" for high performance and flexible thermal insulators.Nanoscale silica and polymer composites are one group of the most popular inorganic-organic composite materials as they have several advantages over the original polymers, e.g., improved mechanical properties, gas barrier function, thermal stability and electrical and optical functions. Monolithic silica aerogels are known for their excellent thermal insulation properties 1,2 and are expected to be a key material for energy conservation. However, high production costs and extreme fragility are crucial drawbacks for their commercial applications. A composite or hybrid of an aerogel with a polymer is a very promising way to overcome these disadvantages. A variety of cross-linking methods with polymers such as isocyanate 3,4 have been investigated. 3-9 However, a silica aerogel-polymer composite frequently faces a trade-off problem between mechanical strength (introduced by the polymer) and thermal resistibility (from the silica).In our quest for exible and high performance thermal insulating materials, we have conceived a new fabrication method for polymer-silica composites. If we can disperse a large amount of silica aerogel as isolated nanoparticles in a polymer matrix, the material is expected to fulll our hope. A conventional mixing process such as melt kneading 10 or solution blending can be employed, but such methods frequently result in aggregation of silica aerogels. Bottom up processes such as in situ polymerization and sol-gel processes are benecial for producing high dispersions of silica. 11 Conversely, these methods tend to provide molecular level hybrids and have difficulty in allowing condensation of a nano-or microscale silica structure, and its localization in the composite. Our new method uses phase separation of a high pressure homogeneous mixture of polymer, monomeric silicon alkoxide (Si(OR) 4 ) and carbon dioxide (CO 2 ). It is well known that high pressure CO 2 dissolves in a variety of polymers and plasticizes them. Thus supercritical CO 2 has frequently been employed as a processing solvent to reduce viscosity and to accelerate the mixing of reagents into the polymer. 12 As for polymer-silica nanocomposites, the use of supercritical CO 2 has been studied for macroporous poly(methyl methacrylate)-silica, 13 polypropylene-silica, 14 poly(vinyl acetate)-silica, 15 polystyrenesilica 16 and polypyrrole-silica 17 systems. We have focused on the fact that some Si(OR) 4 species and CO 2 become a homogeneous mixture under high pressure. 18 If the mixture is dissolved into polymers to be a h...

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confidence: 99%

A porous polymer–silica composite with a “vespula-like” structure for thermal insulating materials prepared via high pressure phase control

et al. 2013

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“…1). The as‐synthesized ZrO 2 particles were not dispersible in CO 2 but were dispersed after modification with MPTMS, which is due to the favorable interaction between MPTMS molecules and CO 2 17. The procedure involved in the preparation of PMMA/ZrO 2 hybrid composite consisted of two steps.…”

Section: Resultsmentioning

confidence: 99%

“…Though few studies have been reported based on the polymer/polymer composites, reports on the synthesis of polymer/inorganic oxide composites in scCO 2 are scarce in the literature. Yue et al synthesized macroporous monoliths consisting of silica nanoparticles embedded in poly(methyl methacrylate) (PMMA) via a one step sol–gel process in scCO 2 17. Recently, PMMA/SiO 2 ,18 PS/C 60 ,19 PVAc/SiO 2 20 and PS/SiO 2 21 nanocomposites were also synthesized in scCO 2 .…”

Section: Introductionmentioning

confidence: 99%

Core‐shell ZrO₂/PMMA composites via dispersion polymerization in supercritical fluid: Synthesis, characterization and mechanism

Haldorai

Zong

Shim

2011

J of Applied Polymer Sci

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Zirconia (ZrO 2 ) particles of average size 200 nm were synthesized by sol-gel method and formation of composites with poly(methyl methacrylate) (PMMA) via in situ radical dispersion polymerization in supercritical carbon dioxide (scCO 2 ) using a commercially available stabilizer poly(dimethylsiloxane)-g-pyrrolidone carboxylic acid (Monosil PCA). ZrO 2 particles were first surface-modified by the silane coupling agent methacryloxypropyltrimethoxysilane (MPTMS), which is capable of copolymerizing with methyl methacrylate (MMA) and provide a reactive C¼ ¼C bond. SEM results revealed uniform morphological characteristics of the composite materials and good dispersions of the ZrO 2 particles. TEM analysis confirmed the core-shell morphology. The incorporation of ZrO 2 particles in the composites was endorsed by FT-IR. The composites were also confirmed by TGA and XRD. The hybrid composites possess interesting thermal and optical transparency characteristics because of the uniform incorporation of ZrO 2 particles in the polymer matrix. In principle, this simple and environmentally friendly synthetic procedure can be employed to prepare other inorganic oxide containing polymer composites.

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“…The TiO 2 particles could be dispersed in scCO 2 after modification with the silylating agent -MPS, which is due to the favorable interaction between -MPS molecules and CO 2 . 17 Polymerization reactions were carried out with varying ratio of TiO 2 nanoparticles (5% to 15% w/w to P3OT) to 3-octylthiophene in supercritical carbon dioxide. The apparent physical nature of P3OT changed remarkably after composite formation.…”

Section: Resultsmentioning

confidence: 99%

A Facile Synthesis of Poly(3-octylthiophene)-Titanium Dioxide Nanocomposite Particles in Supercritical CO₂

Haldorai¹,

Woo²,

Park³

et al. 2008

j nanosci nanotechnol

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Poly(3-octylthiophene) (P3OT)-titanium dioxide (TiO2) nanocomposite powder where TiO2 was embedded with homogeneous dispersion was synthesized by in-situ chemical oxidative polymerization of 3-octylthiophene in the presence of TiO2 nanoparticles in supercritical carbon dioxide (scCO2), using ferric chloride as the oxidant. The synthesized materials could be obtained as dry powder upon venting of CO2 after the polymerization. The composites were subsequently characterized by FT-IR spectroscopy, transmission electron microscopy (TEM), X-ray diffraction studies (XRD), thermogravimetric analysis (TGA) and photoluminescence (PL). The incorporation of TiO2 in the composite was endorsed by FT-IR studies. TGA revealed enhanced thermal stability of P3OT/TiO2 nanocomposite compared to 3-octylthiophene. TEM analysis showed that well dispersed TiO2 nanoparticles in the polymer matrix. Photoluminescence quenching increased with increasing TiO2 concentration in the composite.

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Synthesis of Macroporous PMMA/Silica Nanocomposite Monoliths in Supercritical Carbon Dioxide

Cited by 19 publications

References 27 publications

A porous polymer–silica composite with a “vespula-like” structure for thermal insulating materials prepared via high pressure phase control

A porous polymer–silica composite with a “vespula-like” structure for thermal insulating materials prepared via high pressure phase control

Core‐shell ZrO₂/PMMA composites via dispersion polymerization in supercritical fluid: Synthesis, characterization and mechanism

A Facile Synthesis of Poly(3-octylthiophene)-Titanium Dioxide Nanocomposite Particles in Supercritical CO₂

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Synthesis of Macroporous PMMA/Silica Nanocomposite Monoliths in Supercritical Carbon Dioxide

Cited by 19 publications

References 27 publications

A porous polymer–silica composite with a “vespula-like” structure for thermal insulating materials prepared via high pressure phase control

A porous polymer–silica composite with a “vespula-like” structure for thermal insulating materials prepared via high pressure phase control

Core‐shell ZrO2/PMMA composites via dispersion polymerization in supercritical fluid: Synthesis, characterization and mechanism

A Facile Synthesis of Poly(3-octylthiophene)-Titanium Dioxide Nanocomposite Particles in Supercritical CO2

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Core‐shell ZrO₂/PMMA composites via dispersion polymerization in supercritical fluid: Synthesis, characterization and mechanism

A Facile Synthesis of Poly(3-octylthiophene)-Titanium Dioxide Nanocomposite Particles in Supercritical CO₂