Abstract: A process for preparing nanoparticle coated surfaces including the steps of electrostatically coating surfaces with polyelectrolyte by exposing the surface to a solution or suspension of polyelectrolyte, removing excess non-bound polyelectrolyte, then further coating the particles with a multi-layer of charged nanoparticles by exposing the polyelectrolyte-coated surface to a fluid dispersion including the charged nanoparticles. The process steps can optionally be repeated thereby adding further layers of polyelectrolyte followed by nanoparticles as many times as desired to produce a second and subsequent layers. The polyelectrolyte has an opposite surface charge to the charged nanoparticles and a molecular weight at the ionic strength of the fluid that is effective so that the first, second, and subsequent layers independently comprise a multiplicity of nanoparticle layers that are thicker than monolayers.

Abstract: A process for preparing nanoparticle coated surfaces including the steps of electrostatically coating surfaces with polyelectrolyte by exposing the surface to a solution or suspension of polyelectrolyte, removing excess non-bound polyelectrolyte, then further coating the particles with a multi-layer of charged nanoparticles by exposing the polyelectrolyte-coated surface to a fluid dispersion including the charged nanoparticles. The process steps can optionally be repeated thereby adding further layers of polyelectrolyte followed by nanoparticles as many times as desired to produce a second and subsequent layers. The polyelectrolyte has an opposite surface charge to the charged nanoparticles and a molecular weight at the ionic strength of the fluid that is effective so that the first, second, and subsequent layers independently comprise a multiplicity of nanoparticle layers that are thicker than monolayers.

Abstract: The present invention relates to microparticles, particularly spherical silica microparticles, which may be useful in liquid chromatography. Specifically, the microparticles include a solid core and an outer porous shell surrounding and irreversibly joined to the core. The shell is composed of a plurality of colloidal nanoparticles, which are applied using an electrostatic multi-multilayering method. The resulting microparticles have a small particle diameter, such as about 1 ?m to 3.5 ?m, a high particle density, such as about 1.2 g/cc to 1.9 g/cc, and a high surface area, such as about 50 m2/g to 165 m2/g. These microparticles can be used to form packed beds and liquid chromatographic columns, which are more efficient and rugged than conventional liquid chromatographic columns.

Abstract: Highly purified, porous silica microspheres contain functional groups which are capable of selectively binding to reaction impurities, such as excess reactant or reaction by-products, which are contained in a reaction medium. The reaction impurities can thereby be efficiently removed from the reaction medium, providing a convenient method for product purification.

Abstract: Highly purified, porous silica microspheres contain functional groups which are capable of selectively binding to reaction impurities, such as excess reactant or reaction by-products, which are contained in a reaction medium. The reaction impurities can thereby be efficiently removed from the reaction medium, providing a convenient method for product purification.

Abstract: Highly purified, porous silica microspheres contain functional groups which are capable of selectively binding to reaction impurities, such as excess reactant or reaction by-products, which are contained in a reaction medium. The reaction impurities can thereby be efficiently removed from the reaction medium, providing a convenient method for product purification.

Abstract: Highly purified, porous silica microspheres contain functional groups which are capable of selectively binding to reaction impurities, such as excess reactant or reaction by-products, which are contained in a reaction medium. The reaction impurities can thereby be efficiently removed from the reaction medium, providing a convenient method for product purification.

Abstract: Highly purified, porous silica microspheres contain functional groups which are capable of selectively binding to reaction impurities, such as excess reactant or reaction by-products, which are contained in a reaction medium. The reaction impurities can thereby be efficiently removed from the reaction medium, providing a convenient method for product purification.

Abstract: Highly purified, porous silica microspheres contain functional groups which are capable of selectively binding to reaction impurities, such as excess reactant or reaction by-products, which are contained in a reaction medium. The reaction impurities can thereby be efficiently removed from the reaction medium, providing a convenient method for product purification.

Abstract: The present invention provides propylene-bridged bidentate silane reagents for modifying the surface of liquid chromatography supports, these supports and methods of making and using the same. When bonded to the surface of a support material, the resulting modified support material provides improved properties, such as better separations and more stable support materials, especially when used in liquid chromatography. These bidentate silanes have the general structure: RSiMe(NMe.sub.2)--(CH.sub.2).sub.3 --SiMeR--NMe.sub.2. R is an n-octadecyl group or an n-tetradecyl group, and Me is a methyl group. When reacted with a silica surface, the resulting modified surface has a structure: PSiO--[RSiMe--(CH.sub.2).sub.3 --SiMeR]--OSiP. PSiO is surface-reacted silica.

Abstract: The present invention provides propylene-bridged bidentate silane reagents for modifying the surface of liquid chromatography supports, these supports and methods of making and using the same. When bonded to the surface of a support material, the resulting modified support material provides improved properties, such as better separations and more stable support materials, especially when used in liquid chromatography. These bidentate silanes have the general structure: RSiMe(NMe.sub.2)--(CH.sub.2).sub.3 --SiMeR--NMe.sub.2. R is an n-octadecyl group or an n-tetradecyl group, and Me is a methyl group. When reacted with a silica surface, the resulting modified surface has a structure: PSiO--?RSiMe--(CH.sub.2).sub.3 --SiMeR!--OSiP. PSiO is surface-reacted silica.

Abstract: The present invention provides asymmetric bidentate silane reagents from modifying the surface of liquid chromatography supports, the supports and methods of making and using the same. When bonded to the surface of a support material, the resulting modified support material provides improved properties, such as better separations and more stable support materials, especially when used in liquid chromatography. These bidentate silanes have the general structure: R.sub.1 SiMe(NMe.sub.2)--(CH.sub.2).sub.n --SiMeR.sub.2 (NMe.sub.2). R.sub.1 is an alkyl group having from 1 to 30 carbon atoms, and R.sub.2 is an alkyl group having from 8 to 18 carbon atoms. R.sub.1 is a different alkyl group than R.sub.2. Me is a methyl group, and n has a value 2 or 3. In certain embodiments, R.sub.2 includes at least one functional group. When reacted with a silica surface, the resulting modified surface has a structure: PSiO--?R.sub.1 SiMe--(CH.sub.2).sub.n --SiMeR!--OSiP. PSiO is a surface reacted silica.

Abstract: Chromatographic material comprising porous silica microspheres having silanol-enriched and completely silanized surfaces are disclosed. Processes for preparing the specified chromatographic material are also disclosed.

Abstract: Chromatographic materials comprising porous silica microspheres having silanol-enriched and completely silanized surfaces are disclosed. Processes for preparing the specified chromatographic material are also disclosed.

Abstract: Chromatographic materials comprising porous silica microspheres having silanol-enriched and completely silanized surfaces are disclosed. Processes for preparing the specified chromatographic material are also disclosed.

Abstract: This invention involves unique compositions consisting of substrates coated with organo-silanes that are sterically protected by a single bulky group. This material consists of an appropriate reactive solid to which is attached a silane whose silicon stom is bonded to a functional group that contains a dimethyl-substituted tertiary carbon.

Abstract: A bidentate silane containing at least two silicon atoms bridged by certain groups, arranged to form at least a seven member ring system, is formed between the bidentate silane and the atoms to which the silane is covalently attached on the substrate surface.

Abstract: This invention relates to unique stable support structures comprising substrates coated with sterically-protecting monofunctional silanes. This structure consists of an appropriate reactive solid to which a monofunctional silane is covalently bonded that contains at least two sterically-protecting groups attached to the silicon atom of the silane.

Abstract: There is disclosed a process for preparing superficially porous macroparticles comprising spray drying a specified well-mixed slurry of core macroparticles, colloidal inorganic microparticles and a liquid and sintering the resulting product to cause a 5%-30% decrease in surface area.

Abstract: A plastic ring has a circumferential groove formed in its outer peripheral surface. The ring is fitted in a bowl-type centrifuge rotor such that the ring's outer surface contacts the inner wall of the rotor. The channel is defined by the groove and rotor wall. The rotor is filled with a compensating liquid to reduce centrifugal stress on the plastic and to reduce leakage from the channel.