Gifty Osei-Prempeh - Academia.edu (original) (raw)

Papers by Gifty Osei-Prempeh

Research paper thumbnail of Preliminary Results of Experiments on a Single Cell Polymer Electrolyte Fuel Cell Fueled With Carbon Monoxide

Coal-fueled fuel cells can be an important part of the future power generation infrastructure. Th... more Coal-fueled fuel cells can be an important part of the future power generation infrastructure. The coal can be gasified through partial oxidation process to produce a carbon monoxide rich gaseous fuel. But this fuel gas cannot be used as fuel in the conventional polymer electrolyte fuel cells (PEFC). The idea that is introduced and investigated in this paper is to develop a single cell PEFC that can be fueled with carbon monoxide. It is shown that this idea is feasible. Also, the preliminary results of the experiments are presented to investigate the effects of various design, fabrication, and operational conditions on the performance of the single cell PEFC fueled with carbon monoxide.

Research paper thumbnail of Influence of Polymer Surface Charge on the Synthesis and Properties of Polymer-Silica Composites

Industrial & Engineering Chemistry Research, 2015

Silica–polymer composites using positively charged polystyrene and Amberlite beads and neutral Am... more Silica–polymer composites using positively charged polystyrene and Amberlite beads and neutral Amberlite beads as seeds were prepared in an acidic silica synthesis medium. The potential for functionalization of the composites for specific applications depends on the inorganic (silica) phase present. The synthesized composites were characterized by determining the percentage of organic content, particle size, surface area, and pore size and volume and the percentage of CO2 adsorbed to investigate the potential for specific application. The use of positively charged polymers resulted in a higher content of silica incorporated, leading to an increase in the composite particle size and a higher incorporation of the amine functional group. Application of the composites for CO2 adsorption shows higher sorption rates in the composites made with positively charged polymer seeds. The highest amount of CO2 adsorbed is seen in the amine-functionalized composite made from Amberlite IRA-900 Cl, positively charged poly...

Research paper thumbnail of 275606 Indirect Carbon (CO) PEM Fuel Cell

Research paper thumbnail of Synthesis and Characterization of Sugar-Imprinted Titanosilicate Materials Prepared by Surfactant Co-Templating

Templated silica materials synthesized and developed during the past two decades have found a lar... more Templated silica materials synthesized and developed during the past two decades have found a large number of potential applications in the fields of catalysis, sensing, optics and separations. Recently, our group began investigating using mixed surfactant templating for preparation of selective adsorbent materials for saccharide separations. The immediate targets are C5/C6 sugar separations to allow better utilization of the different types of sugars generated during hydrolysis of lignocellulosic biomass. Our approach utilizes interactions between specific surfactant headgroups and precursors to allow the surfactant not only to act as a passive space-filling pore-template, but also to actively direct the formation of complementary sites for separation of target compounds. Silica is a wonderfully versatile matrix for mesoporous materials, but it does not necessarily exhibit strong binding to sugars. Titania is known to provide high affinity for biomolecules, and incorporation of tit...

Research paper thumbnail of Effects of Imprint Molecule and Imprinting Technique On Sugar Adsorption On Nanostructured Molecular Imprinted Silica

Lignocellulosic biomass (e.g. switch grass and corn stover) is an abundant source of raw material... more Lignocellulosic biomass (e.g. switch grass and corn stover) is an abundant source of raw material for biofuels production. The hydrolyzed products of cellulosic biomass (e.g. glucose, xylose and cellobiose) are known to inhibit the enzymatic saccharification (cellulose depolymerisation) process in cellulosic ethanol production. Separation of the sugar components in the pre-treated biomass will improve ethanol yield by the removal of some of the inhibitants and also generate clean saccharide (e.g. xylose) stream for further conversion to valuable commodity chemicals. This will provide efficient utilization of most of the sugar components in the biomass hydrolysates. Here, molecular imprinting is used to create recognition sites by using surfactants derived from the target molecule to be separated as templates. Sugar based surfactants (e.g. n-octyl-β-D-glucopyranoside and n-octyl-β-D-xylopyranoside) are used in addition to a co-template (CTAB) to obtain nanostructured molecular imprin...

Research paper thumbnail of Effects of Functional Groups in Molecular Imprinted Silica On Adsorption of Sugars From Cellulosic Biomass

In cellulose based biofuel production, the hydrolyzed products of cellulosic biomass (e.g glucose... more In cellulose based biofuel production, the hydrolyzed products of cellulosic biomass (e.g glucose, xylose and cellobiose) are known to inhibit the enzymatic saccharification (cellulose depolymerisation) process. In order to obtain higher sugar yields and consequently ethanol yields, a means to separate out some of the inhibition products will help drive the enzymatic reaction forward. Here, molecular imprinting is used to create recognition sites by using surfactants derived from the target molecule to be separated as a template. Sugar based surfactants (e.g. n-octyl--D-glucopyranoside) are used in addition to a co-template (CTAB) to obtain nanostructured molecular imprinted (NMI) silica in a sol-gel procedure utilizing two synthesis methods: precipitation and nanocasting. After surfactant extraction the silica materials are hypothesized to possess sites that can recognize specific sugar molecules. Unfortunately, isothermal titration calorimetry (ITC) analyses of the adsorption of s...

Research paper thumbnail of Preliminary Results of Experiments on a Single Cell Polymer Electrolyte Fuel Cell Fueled With Carbon Monoxide

ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology, 2013

Coal-fueled fuel cells can be an important part of the future power generation infrastructure. Th... more Coal-fueled fuel cells can be an important part of the future power generation infrastructure. The coal can be gasified through partial oxidation process to produce a carbon monoxide rich gaseous fuel. But this fuel gas cannot be used as fuel in the conventional polymer electrolyte fuel cells (PEFC). The idea that is introduced and investigated in this paper is to develop a single cell PEFC that can be fueled with carbon monoxide. It is shown that this idea is feasible. Also, the preliminary results of the experiments are presented to investigate the effects of various design, fabrication, and operational conditions on the performance of the single cell PEFC fueled with carbon monoxide.

Research paper thumbnail of Molecular Imprinted Silica for Sepration of Sugars from Cellulosic Biomass

Research paper thumbnail of Direct Synthesis and Accessibility of Amine-Functionalized Mesoporous Silica Templated Using Fluorinated Surfactants

Industrial & Engineering Chemistry Research, 2011

3-Aminopropyl functionalized silica is synthesized directly using cationic fluorinated surfactant... more 3-Aminopropyl functionalized silica is synthesized directly using cationic fluorinated surfactants (C6F13C2H2NC5H5Cl (HFOPC) and C8F17C2H2NC5H5Cl (HFDePC)) and a hydrocarbon surfactant (C16H33N (CH3) 3Br (CTAB)) as templates. The resulting 3-...

Research paper thumbnail of Synthesis, thermal properties, and cytotoxicity evaluation of hydrocarbon and fluorocarbon alkyl β-d-xylopyranoside surfactants

Carbohydrate Research, 2012

Alkyl β-D-xylopyranosides are highly surface active, biodegradable surfactants that can be prepar... more Alkyl β-D-xylopyranosides are highly surface active, biodegradable surfactants that can be prepared from hemicelluloses and are of interest for use as pharmaceuticals, detergents, agrochemicals and personal care products. To gain further insights into their structure-property and structure-activity relationships, the present study synthesized a series of hydrocarbon (-C 6 H 13 to-C 16 H 33) and fluorocarbon (-(CH 2) 2 C 6 F 13) alkyl β-D-xylopyranosides in four steps from Dxylose by acylation or benzoylation, bromination, Koenigs-Knorr reaction and hydrolysis, with the benzoyl protecting group giving better yields compared to the acyl group in the Koenigs-Knorr reaction. All alkyl β-D-xylopyranosides formed thermotropic liquid crystals. The phase transition of the solid crystalline phase to a liquid crystalline phase increased linearly with the length of the hydrophobic tail. The clearing points were near constant for alkyl β-D-xylopyranosides with a hydrophobic tail ≥ 8, but occurred at a significantly lower temperature for hexyl β-Dxylopyranoside. Short and long-chain alkyl β-D-xylopyranosides displayed no cytotoxicity at concentration below their aqueous solubility limit. Hydrocarbon and fluorocarbon alkyl β-Dxylopyranosides with intermediate chain length displayed some toxicity at millimolar concentrations due to apoptosis.

Research paper thumbnail of Synthesis and Application of Fluorocarbon Functionalized Mesoporous Silica

Materkals …, 2006

The pore structure of mesoporous silica materials synthesized by sol-gel processing can be tailor... more The pore structure of mesoporous silica materials synthesized by sol-gel processing can be tailored through the choice of surfactants or polymers templates. The direct incorporation organic groups into the framework of these materials through the incorporation of organic ...

Research paper thumbnail of Comparison of Fluorocarbon and Hydrocarbon Functional Group Incorporation into Nanoporous Silica Using Fluorinated and Hydrocarbon Surfactants as Templating …

The 2005 Annual …, 2005

Organic functionalized nanoporous silica particles have been successfully synthesized by the &#x2... more Organic functionalized nanoporous silica particles have been successfully synthesized by the 'one-pot' (direct) synthesis method using two cationic fluorinated surfactants, C 6 F 13 C 2 H 2 NC 5 H 5 Cl (FSPCl-1) and C 8 F 17 C 2 H 2 NC 5 H 5 Cl (FSPCl-2), a hydrocarbon ...

Research paper thumbnail of Making A Chemical Process Control Course an Inductive and Deductive Learning Experience

Chemical Engineering Education, 2010

The preponderance of the evidence from the engineering education literature demonstrates that ind... more The preponderance of the evidence from the engineering education literature demonstrates that inductive teaching methods are more effective than deductive approaches. When students are already familiar with the fundamentals of a topic, however, deductive approaches may ...

Research paper thumbnail of Bi-Functionalized Mesoporous Silica Synthesized Using Fluorinated Surfactants as Template

The 2005 Annual …, 2005

The recent demonstration of cationic fluorocarbon surfactants for the templating of mesoporous si... more The recent demonstration of cationic fluorocarbon surfactants for the templating of mesoporous silica is extended to organic-inorganic hybrids through direct synthesis. The potential to align functional group in the pores of the templated silica material through the interactions of ...

Research paper thumbnail of Synthesis and Applications of Organic Functionalized Nanoporous Silica

The 2008 Annual Meeting, 2008

Incorporation of long chain hydrocarbon and fluorocarbon functional groups, and reactive amine fu... more Incorporation of long chain hydrocarbon and fluorocarbon functional groups, and reactive amine functional group in nanoporous silica using fluorinated and hydrocarbon surfactants as templates was investigated in this research. Surfactant/functional group combinations and the ...

Research paper thumbnail of FUNCTIONALIZATION OF FLUORINATED SURFACTANT TEMPLATED SILICA

OF DISSERTATION FUNCTIONALIZATION OF FLUORINATED SURFACTANT TEMPLATED SILICA

Research paper thumbnail of Fluorocarbon and hydrocarbon functional group incorporation into nanoporous silica employing fluorinated and hydrocarbon surfactants as templates

Microporous and Mesoporous Materials, 2010

Ordered mesoporous hydrocarbon functionalized (n-decyl) silica samples are synthesized by the 'on... more Ordered mesoporous hydrocarbon functionalized (n-decyl) silica samples are synthesized by the 'onepot' (direct) synthesis method using two cationic fluorinated surfactants, C 6 F 13 C 2 H 2 NC 5 H 5 Cl (HFOPC) and C 8 F 17 C 2 H 2 NC 5 H 5 Cl (HFDePC), and a typical hydrocarbon surfactant, C 16 H 33 N(CH 3 ) 3 Br (CTAB), as templates. The properties of the materials are compared to those of silica samples functionalized with a fluorocarbon functional group, heptadecafluoro-1,1,2,2-tetrahydro-decyl, whose fluorocarbon separating ability was reported earlier . The pore characteristics, organic loading, and wetting properties of the resulting materials are determined for the following combinations of surfactant/functional groups: hydrocarbon/hydrocarbon, hydrocarbon/fluorocarbon, fluorocarbon/hydrocarbon and fluorocarbon/fluorocarbon. Synthesis using the longer chain fluoro-surfactant (HFDePC) template results in the highest incorporation of both n-decyl and fluorocarbon functional groups, with a corresponding loss of longrange pore order in the fluorinated material. Materials synthesized using the HFOPC template have very low levels of functional group incorporation compared to the HFDePC-templated materials. CTAB-templated materials display greater long-range pore order than the fluorocarbon templated materials. The incorporation of the fluorocarbon functional precursor is more effective (on a % yield basis) than the hydrocarbon functional precursor for silica materials synthesized using CTAB. Similarly, the use of fluorinated surfactant templates enhances fluorocarbon incorporation relative to hydrocarbon incorporation in the mesoporous material. Solubility of the precursors (n-decyltriethoxysilane and heptadecafluoro-1,1,2,2-tetrahydro-decyltriethoxysilane) in the synthesis medium and favorable aggregation behavior of the alkane/fluoroalkane functional groups with the surfactant micelles improves the incorporation of the functional group.

Research paper thumbnail of Synthesis of Fluoro-Functionalized Mesoporous Silica and Application to Fluorophilic Separations

Industrial & Engineering Chemistry Research, 2008

Fluorocarbon-functionalized mesoporous silica is synthesized by the co-condensation of tetraalkox... more Fluorocarbon-functionalized mesoporous silica is synthesized by the co-condensation of tetraalkoxysilane and fluoro-functionalized alkoxysilane precursors using a cationic fluorocarbon surfactant, C 6 F 13 C 2 H 2 NC 5 H 5 Cl (HFOPC) and C 8 F 17 C 2 H 2 NC 5 H 5 Cl (HFDePC), or a ...

Research paper thumbnail of Fluorinated surfactant templating of vinyl-functionalized nanoporous silica

Microporous and Mesoporous Materials, 2005

Ordered nanoporous vinyl-functionalized silica materials are synthesized by the Ôone-potÕ (direct... more Ordered nanoporous vinyl-functionalized silica materials are synthesized by the Ôone-potÕ (direct) synthesis method using three cationic fluorinated surfactants (C 6 F 13 C 2 H 4 NC 5 H 5 Cl, C 8 F 17 C 2 H 4 NC 5 H 5 Cl and C 10 F 21 C 2 H 4 NC 5 H 5 Cl) as templates in basic medium under ambient conditions. The materials obtained possess lower degrees of 2D hexagonal closed packed ordering of the pores when compared to CTAB templated materials. Increases in vinyl content lead to reductions in pore size as well as material order. In spite of having smaller pores, bromination experiments suggest that the vinyl groups are more accessible in the fluoro-surfactant templated materials. Although confinement of the vinyl groups to the palisade region of the fluorinated micelle templates may contribute to this increase in accessibility, reduced pore order in the fluorinated templated materials may also improve the accessibility, as observed here for intentionally disordered CTAB-templated materials. Cationic fluorocarbon surfactants not only have the potential to be templating agents, but also present the possibility of re-organizing the alignment of organic functional groups in the pores of organic-inorganic hybrids obtained by direct synthesis.

Research paper thumbnail of Preliminary Results of Experiments on a Single Cell Polymer Electrolyte Fuel Cell Fueled With Carbon Monoxide

Coal-fueled fuel cells can be an important part of the future power generation infrastructure. Th... more Coal-fueled fuel cells can be an important part of the future power generation infrastructure. The coal can be gasified through partial oxidation process to produce a carbon monoxide rich gaseous fuel. But this fuel gas cannot be used as fuel in the conventional polymer electrolyte fuel cells (PEFC). The idea that is introduced and investigated in this paper is to develop a single cell PEFC that can be fueled with carbon monoxide. It is shown that this idea is feasible. Also, the preliminary results of the experiments are presented to investigate the effects of various design, fabrication, and operational conditions on the performance of the single cell PEFC fueled with carbon monoxide.

Research paper thumbnail of Influence of Polymer Surface Charge on the Synthesis and Properties of Polymer-Silica Composites

Industrial & Engineering Chemistry Research, 2015

Silica–polymer composites using positively charged polystyrene and Amberlite beads and neutral Am... more Silica–polymer composites using positively charged polystyrene and Amberlite beads and neutral Amberlite beads as seeds were prepared in an acidic silica synthesis medium. The potential for functionalization of the composites for specific applications depends on the inorganic (silica) phase present. The synthesized composites were characterized by determining the percentage of organic content, particle size, surface area, and pore size and volume and the percentage of CO2 adsorbed to investigate the potential for specific application. The use of positively charged polymers resulted in a higher content of silica incorporated, leading to an increase in the composite particle size and a higher incorporation of the amine functional group. Application of the composites for CO2 adsorption shows higher sorption rates in the composites made with positively charged polymer seeds. The highest amount of CO2 adsorbed is seen in the amine-functionalized composite made from Amberlite IRA-900 Cl, positively charged poly...

Research paper thumbnail of 275606 Indirect Carbon (CO) PEM Fuel Cell

Research paper thumbnail of Synthesis and Characterization of Sugar-Imprinted Titanosilicate Materials Prepared by Surfactant Co-Templating

Templated silica materials synthesized and developed during the past two decades have found a lar... more Templated silica materials synthesized and developed during the past two decades have found a large number of potential applications in the fields of catalysis, sensing, optics and separations. Recently, our group began investigating using mixed surfactant templating for preparation of selective adsorbent materials for saccharide separations. The immediate targets are C5/C6 sugar separations to allow better utilization of the different types of sugars generated during hydrolysis of lignocellulosic biomass. Our approach utilizes interactions between specific surfactant headgroups and precursors to allow the surfactant not only to act as a passive space-filling pore-template, but also to actively direct the formation of complementary sites for separation of target compounds. Silica is a wonderfully versatile matrix for mesoporous materials, but it does not necessarily exhibit strong binding to sugars. Titania is known to provide high affinity for biomolecules, and incorporation of tit...

Research paper thumbnail of Effects of Imprint Molecule and Imprinting Technique On Sugar Adsorption On Nanostructured Molecular Imprinted Silica

Lignocellulosic biomass (e.g. switch grass and corn stover) is an abundant source of raw material... more Lignocellulosic biomass (e.g. switch grass and corn stover) is an abundant source of raw material for biofuels production. The hydrolyzed products of cellulosic biomass (e.g. glucose, xylose and cellobiose) are known to inhibit the enzymatic saccharification (cellulose depolymerisation) process in cellulosic ethanol production. Separation of the sugar components in the pre-treated biomass will improve ethanol yield by the removal of some of the inhibitants and also generate clean saccharide (e.g. xylose) stream for further conversion to valuable commodity chemicals. This will provide efficient utilization of most of the sugar components in the biomass hydrolysates. Here, molecular imprinting is used to create recognition sites by using surfactants derived from the target molecule to be separated as templates. Sugar based surfactants (e.g. n-octyl-β-D-glucopyranoside and n-octyl-β-D-xylopyranoside) are used in addition to a co-template (CTAB) to obtain nanostructured molecular imprin...

Research paper thumbnail of Effects of Functional Groups in Molecular Imprinted Silica On Adsorption of Sugars From Cellulosic Biomass

In cellulose based biofuel production, the hydrolyzed products of cellulosic biomass (e.g glucose... more In cellulose based biofuel production, the hydrolyzed products of cellulosic biomass (e.g glucose, xylose and cellobiose) are known to inhibit the enzymatic saccharification (cellulose depolymerisation) process. In order to obtain higher sugar yields and consequently ethanol yields, a means to separate out some of the inhibition products will help drive the enzymatic reaction forward. Here, molecular imprinting is used to create recognition sites by using surfactants derived from the target molecule to be separated as a template. Sugar based surfactants (e.g. n-octyl--D-glucopyranoside) are used in addition to a co-template (CTAB) to obtain nanostructured molecular imprinted (NMI) silica in a sol-gel procedure utilizing two synthesis methods: precipitation and nanocasting. After surfactant extraction the silica materials are hypothesized to possess sites that can recognize specific sugar molecules. Unfortunately, isothermal titration calorimetry (ITC) analyses of the adsorption of s...

Research paper thumbnail of Preliminary Results of Experiments on a Single Cell Polymer Electrolyte Fuel Cell Fueled With Carbon Monoxide

ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology, 2013

Coal-fueled fuel cells can be an important part of the future power generation infrastructure. Th... more Coal-fueled fuel cells can be an important part of the future power generation infrastructure. The coal can be gasified through partial oxidation process to produce a carbon monoxide rich gaseous fuel. But this fuel gas cannot be used as fuel in the conventional polymer electrolyte fuel cells (PEFC). The idea that is introduced and investigated in this paper is to develop a single cell PEFC that can be fueled with carbon monoxide. It is shown that this idea is feasible. Also, the preliminary results of the experiments are presented to investigate the effects of various design, fabrication, and operational conditions on the performance of the single cell PEFC fueled with carbon monoxide.

Research paper thumbnail of Molecular Imprinted Silica for Sepration of Sugars from Cellulosic Biomass

Research paper thumbnail of Direct Synthesis and Accessibility of Amine-Functionalized Mesoporous Silica Templated Using Fluorinated Surfactants

Industrial & Engineering Chemistry Research, 2011

3-Aminopropyl functionalized silica is synthesized directly using cationic fluorinated surfactant... more 3-Aminopropyl functionalized silica is synthesized directly using cationic fluorinated surfactants (C6F13C2H2NC5H5Cl (HFOPC) and C8F17C2H2NC5H5Cl (HFDePC)) and a hydrocarbon surfactant (C16H33N (CH3) 3Br (CTAB)) as templates. The resulting 3-...

Research paper thumbnail of Synthesis, thermal properties, and cytotoxicity evaluation of hydrocarbon and fluorocarbon alkyl β-d-xylopyranoside surfactants

Carbohydrate Research, 2012

Alkyl β-D-xylopyranosides are highly surface active, biodegradable surfactants that can be prepar... more Alkyl β-D-xylopyranosides are highly surface active, biodegradable surfactants that can be prepared from hemicelluloses and are of interest for use as pharmaceuticals, detergents, agrochemicals and personal care products. To gain further insights into their structure-property and structure-activity relationships, the present study synthesized a series of hydrocarbon (-C 6 H 13 to-C 16 H 33) and fluorocarbon (-(CH 2) 2 C 6 F 13) alkyl β-D-xylopyranosides in four steps from Dxylose by acylation or benzoylation, bromination, Koenigs-Knorr reaction and hydrolysis, with the benzoyl protecting group giving better yields compared to the acyl group in the Koenigs-Knorr reaction. All alkyl β-D-xylopyranosides formed thermotropic liquid crystals. The phase transition of the solid crystalline phase to a liquid crystalline phase increased linearly with the length of the hydrophobic tail. The clearing points were near constant for alkyl β-D-xylopyranosides with a hydrophobic tail ≥ 8, but occurred at a significantly lower temperature for hexyl β-Dxylopyranoside. Short and long-chain alkyl β-D-xylopyranosides displayed no cytotoxicity at concentration below their aqueous solubility limit. Hydrocarbon and fluorocarbon alkyl β-Dxylopyranosides with intermediate chain length displayed some toxicity at millimolar concentrations due to apoptosis.

Research paper thumbnail of Synthesis and Application of Fluorocarbon Functionalized Mesoporous Silica

Materkals …, 2006

The pore structure of mesoporous silica materials synthesized by sol-gel processing can be tailor... more The pore structure of mesoporous silica materials synthesized by sol-gel processing can be tailored through the choice of surfactants or polymers templates. The direct incorporation organic groups into the framework of these materials through the incorporation of organic ...

Research paper thumbnail of Comparison of Fluorocarbon and Hydrocarbon Functional Group Incorporation into Nanoporous Silica Using Fluorinated and Hydrocarbon Surfactants as Templating …

The 2005 Annual …, 2005

Organic functionalized nanoporous silica particles have been successfully synthesized by the &#x2... more Organic functionalized nanoporous silica particles have been successfully synthesized by the 'one-pot' (direct) synthesis method using two cationic fluorinated surfactants, C 6 F 13 C 2 H 2 NC 5 H 5 Cl (FSPCl-1) and C 8 F 17 C 2 H 2 NC 5 H 5 Cl (FSPCl-2), a hydrocarbon ...

Research paper thumbnail of Making A Chemical Process Control Course an Inductive and Deductive Learning Experience

Chemical Engineering Education, 2010

The preponderance of the evidence from the engineering education literature demonstrates that ind... more The preponderance of the evidence from the engineering education literature demonstrates that inductive teaching methods are more effective than deductive approaches. When students are already familiar with the fundamentals of a topic, however, deductive approaches may ...

Research paper thumbnail of Bi-Functionalized Mesoporous Silica Synthesized Using Fluorinated Surfactants as Template

The 2005 Annual …, 2005

The recent demonstration of cationic fluorocarbon surfactants for the templating of mesoporous si... more The recent demonstration of cationic fluorocarbon surfactants for the templating of mesoporous silica is extended to organic-inorganic hybrids through direct synthesis. The potential to align functional group in the pores of the templated silica material through the interactions of ...

Research paper thumbnail of Synthesis and Applications of Organic Functionalized Nanoporous Silica

The 2008 Annual Meeting, 2008

Incorporation of long chain hydrocarbon and fluorocarbon functional groups, and reactive amine fu... more Incorporation of long chain hydrocarbon and fluorocarbon functional groups, and reactive amine functional group in nanoporous silica using fluorinated and hydrocarbon surfactants as templates was investigated in this research. Surfactant/functional group combinations and the ...

Research paper thumbnail of FUNCTIONALIZATION OF FLUORINATED SURFACTANT TEMPLATED SILICA

OF DISSERTATION FUNCTIONALIZATION OF FLUORINATED SURFACTANT TEMPLATED SILICA

Research paper thumbnail of Fluorocarbon and hydrocarbon functional group incorporation into nanoporous silica employing fluorinated and hydrocarbon surfactants as templates

Microporous and Mesoporous Materials, 2010

Ordered mesoporous hydrocarbon functionalized (n-decyl) silica samples are synthesized by the 'on... more Ordered mesoporous hydrocarbon functionalized (n-decyl) silica samples are synthesized by the 'onepot' (direct) synthesis method using two cationic fluorinated surfactants, C 6 F 13 C 2 H 2 NC 5 H 5 Cl (HFOPC) and C 8 F 17 C 2 H 2 NC 5 H 5 Cl (HFDePC), and a typical hydrocarbon surfactant, C 16 H 33 N(CH 3 ) 3 Br (CTAB), as templates. The properties of the materials are compared to those of silica samples functionalized with a fluorocarbon functional group, heptadecafluoro-1,1,2,2-tetrahydro-decyl, whose fluorocarbon separating ability was reported earlier . The pore characteristics, organic loading, and wetting properties of the resulting materials are determined for the following combinations of surfactant/functional groups: hydrocarbon/hydrocarbon, hydrocarbon/fluorocarbon, fluorocarbon/hydrocarbon and fluorocarbon/fluorocarbon. Synthesis using the longer chain fluoro-surfactant (HFDePC) template results in the highest incorporation of both n-decyl and fluorocarbon functional groups, with a corresponding loss of longrange pore order in the fluorinated material. Materials synthesized using the HFOPC template have very low levels of functional group incorporation compared to the HFDePC-templated materials. CTAB-templated materials display greater long-range pore order than the fluorocarbon templated materials. The incorporation of the fluorocarbon functional precursor is more effective (on a % yield basis) than the hydrocarbon functional precursor for silica materials synthesized using CTAB. Similarly, the use of fluorinated surfactant templates enhances fluorocarbon incorporation relative to hydrocarbon incorporation in the mesoporous material. Solubility of the precursors (n-decyltriethoxysilane and heptadecafluoro-1,1,2,2-tetrahydro-decyltriethoxysilane) in the synthesis medium and favorable aggregation behavior of the alkane/fluoroalkane functional groups with the surfactant micelles improves the incorporation of the functional group.

Research paper thumbnail of Synthesis of Fluoro-Functionalized Mesoporous Silica and Application to Fluorophilic Separations

Industrial & Engineering Chemistry Research, 2008

Fluorocarbon-functionalized mesoporous silica is synthesized by the co-condensation of tetraalkox... more Fluorocarbon-functionalized mesoporous silica is synthesized by the co-condensation of tetraalkoxysilane and fluoro-functionalized alkoxysilane precursors using a cationic fluorocarbon surfactant, C 6 F 13 C 2 H 2 NC 5 H 5 Cl (HFOPC) and C 8 F 17 C 2 H 2 NC 5 H 5 Cl (HFDePC), or a ...

Research paper thumbnail of Fluorinated surfactant templating of vinyl-functionalized nanoporous silica

Microporous and Mesoporous Materials, 2005

Ordered nanoporous vinyl-functionalized silica materials are synthesized by the Ôone-potÕ (direct... more Ordered nanoporous vinyl-functionalized silica materials are synthesized by the Ôone-potÕ (direct) synthesis method using three cationic fluorinated surfactants (C 6 F 13 C 2 H 4 NC 5 H 5 Cl, C 8 F 17 C 2 H 4 NC 5 H 5 Cl and C 10 F 21 C 2 H 4 NC 5 H 5 Cl) as templates in basic medium under ambient conditions. The materials obtained possess lower degrees of 2D hexagonal closed packed ordering of the pores when compared to CTAB templated materials. Increases in vinyl content lead to reductions in pore size as well as material order. In spite of having smaller pores, bromination experiments suggest that the vinyl groups are more accessible in the fluoro-surfactant templated materials. Although confinement of the vinyl groups to the palisade region of the fluorinated micelle templates may contribute to this increase in accessibility, reduced pore order in the fluorinated templated materials may also improve the accessibility, as observed here for intentionally disordered CTAB-templated materials. Cationic fluorocarbon surfactants not only have the potential to be templating agents, but also present the possibility of re-organizing the alignment of organic functional groups in the pores of organic-inorganic hybrids obtained by direct synthesis.