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  • 1.
    Atakan, Aylin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Keraudy, Julien
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Mäkie, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Hulteberg, Christian
    Lund Univ, Sweden.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Impact of the morphological and chemical properties of copper-zirconium-SBA-15 catalysts on the conversion and selectivity in carbon dioxide hydrogenation2019In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 546, p. 163-173Article in journal (Refereed)
    Abstract [en]

    A hybrid catalyst consisting of Zr-doped mesoporous silica (Zr-SBA-15) supports with intergrown Cu nanoparticles was used to study the effects of a catalysts chemical states on CO2 hydrogenation. The chemical state of the catalyst was altered by using tetraethyl orthosilicate (TEOS) or sodium metasilicate (SMS) as the silica precursor in the synthesis of the Zr-SBA-15 framework, and infiltration (Inf) or evaporation induced wetness impregnation (EIWI) as the Cu loading method. As a result, the silica precursor mainly affects the activity of the catalyst whereas the Cu loading method alters the selectivity of the products. TEOS materials exhibit a higher catalytic activity compared to SMS materials due to different Zr dispersion and bonding to the silica matrix. EIWI catalysts display selectivity for methanol formation, while the Inf ones enable methanol conversion to DME. This is correlated to a higher Zr content and lower Cu oxidation states of EIWI prepared catalysts. (C) 2019 Elsevier Inc. All rights reserved.

  • 2.
    Atakan, Aylin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Mäkie, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Keraudy, Julien
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Synthesis of a Cu-infiltrated Zr-doped SBA-15 catalyst for CO2 hydrogenation into methanol and dimethyl ethert2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 29, p. 19139-19149Article in journal (Refereed)
    Abstract [en]

    A catalytically active nanoassembly comprising Cu-nanoparticles grown on integrated and active supports (large pore Zr-doped mesoporous SBA-15 silica) has been synthesized and used to promote CO2 hydrogenation. The doped mesoporous material was synthesized using a sal-gel method, in which the pore size was tuned between 11 and 15 nm while maintaining a specific surface area of about 700 m(2) g (1). The subsequent Cu nanoparticle growth was achieved by an infiltration process involving attachment of different functional groups on the external and internal surfaces of the mesoporous structure such that 7-10 nm sized Cu nanoparticles grew preferentially inside the pores. Chemisorption showed improved absorption of both CO2 and H-2 for the assembly compared to pure SBA-15 and 15% of the total CO2 was converted to methanol and dimethyl ether at 250 degrees C and 33 bar.

  • 3.
    Ballem, Mohamed A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Zhang, Xuanjun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Johansson, Emma M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Córdoba, José M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Low Temperature Nanocasting of Ultrafine Hematite Nanoparticles using Mesoporous Silica Molds2012In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 217, p. 269-273Article in journal (Refereed)
    Abstract [en]

    Iron oxide (α-Fe2O3) nanoparticles with very small size, high crystallinity, and narrow size distribution were synthesized by infiltration of Fe(NO3)3.9H2O as an oxide precursor into mesoporous silica (SBA-15 and SBA-16) molds using a wetimpregnation technique. High resolution transmission electron microscopy shows that during the hydrothermal treatment of the precursor at 140 °C for 2 days, stable α-Fe2O3 nanoparticles inside the silica pores are formed. Subsequent leaching out of the silica template by NaOH resulted in well dispersed nanoparticles with an average diameter of ~ 4 nm.

  • 4.
    Ballem, Mohamed
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Synthesis of hollow silica spheres SBA-16 with large-pore diameter2011In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 65, no 7, p. 1066-1068Article in journal (Refereed)
    Abstract [en]

    Hollow silica SBA-16 spheres with cubic ordered mesoporous shells were synthesized by an emulsion-templating method, using Pluronic F127 as a structure-directing agent. tetraethyl orthosilicateas as a silica source and heptane as a cosolvent in the presence of NH4F. The size of these spheres is in the range of 10 to 30 mu m. The shell is about 700 nm thick and consists of large pores, similar to 9 nm in diameter, arranged in a cubic order. After calcination, the spheres maintain their mesoporosity and show a high surface area of 822 m(2)/g. The formation mechanism of the silica hollow spheres is discussed.

  • 5.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Synthesizing and Characterizing Mesoporous Silica SBA-15: A Hands On Laboratory Experiment for Undergraduates Using Various Instrumental Techniques2017In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 94, no 1, p. 91-94Article in journal (Refereed)
    Abstract [en]

    In this laboratory experiment, students learn how to synthesize mesoporous silica of the SBA-15 type and explore how the different synthesis steps affect the final material. Mesoporous materials, especially SBA-15, are often used in the development of new methods for. drug delivery, catalysis, and separation because of the flexibility of tailoring these materials to optimize the performance in different applications. However, the synthesis of mesoporous materials is rarely introduced to undergraduate students. The material synthesis is a simple sol gel process, where small alterations in the synthesis steps can significantly change the material characteristics. The presented laboratory experiment aims to introduce undergraduate students to the synthesis of SBA-15 mesoporous silica with different pore sizes due to alterations in the hydrothermal treatment time and/ or temperature and to give students hands-on experience with important characterization tools, including physisorption, X-ray diffraction, FTIR spectroscopy, and thermogravimetric analysis, to understand the effect of hydrothermal treatment and surfactant removal. Additional synthesis parameters to study, such as surfactant removal, the silica precursor, and pore swelling agents, are also presented. The experiment has been used in teaching of both bachelors and masters students and can be adapted to various instrumental techniques, e.g., scanning electron microscopy for morphology studies, transition electron microscopy for pore structure characterization, etc.

  • 6.
    Björk, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Ulm, Germany.
    Baumann, Bernhard
    Univ Ulm, Germany.
    Hausladen, Florian
    Ulm Univ, Germany.
    Wittig, Rainer
    Ulm Univ, Germany.
    Linden, Mika
    Univ Ulm, Germany.
    Cell adherence and drug delivery from particle based mesoporous silica films2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 31, p. 17745-17753Article in journal (Refereed)
    Abstract [en]

    Spatially and temporally controlled drug delivery is important for implant and tissue engineering applications, as the efficacy and bioavailability of the drug can be enhanced, and can also allow for drugging stem cells at different stages of development. Long-term drug delivery over weeks to months is however difficult to achieve, and coating of 3D surfaces or creating patterned surfaces is a challenge using coating techniques like spin- and dip-coating. In this study, mesoporous films consisting of SBA-15 particles grown onto silicon wafers using wet processing were evaluated as a scaffold for drug delivery. Films with various particle sizes (100-900 nm) and hence thicknesses were grown onto trichloro(octadecyl)silane-functionalized silicon wafers using a direct growth method. Precise patterning of the areas for film growth could be obtained by local removal of the OTS functionalization through laser ablation. The films were incubated with the drug model 3,3 -dioctadecyloxacarbocyanine perchlorate (DiO), and murine myoblast cells (C2C12 cells) were seeded onto films with different particle sizes. Confocal laser scanning microscopy (CLSM) was used to study the cell growth, and a vinculin-mediated adherence of C2C12 cells on all films was verified. The successful loading of DiO into the films was confirmed by UV-vis and CLSM. It was observed that the drugs did not desorb from the particles during 24 hours in cell culture. During adherent growth on the films for 4 h, small amounts of DiO and separate particles were observed inside single cells. After 24 h, a larger number of particles and a strong DiO signal were recorded in the cells, indicating a particle mediated drug uptake. The vast majority of the DiO-loaded particles remained attached to the substrate also after 24 h of incubation, making the films attractive as longer-term reservoirs for drugs on e.g. medical implants.

  • 7.
    Björk, Emma M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Mesoporous Building Blocks: Synthesis and Characterization of Mesoporous Silica Particles and Films2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Catalyst supports, drug delivery systems, hosts for nanoparticles, and solar cells are just some examples of the wide range of exciting applications for mesoporous silica. In order to optimize the performance of a specific application, controlling the material’s morphology and pore size is crucial. For example, short and separated particles are beneficial for drug delivery systems, while for molecular sieves, the pore size is the key parameter.

    In this thesis, mesoporous silica building blocks, crystallites, with hexagonally ordered cylindrical pores were synthesized, with the aim to understand how the synthesis parameters affect the particle morphology and pore size. The synthesis of the particles is performed using a sol-gel process, and in order to increase the pore size, a combination of low temperature, and additions of heptane and NH4F was used. By variations in the amounts of reagents, as well as other synthesis conditions, the particle morphology and pore size could be altered. Separated particles were also grown on or attached to substrates to form films. Also, a material with spherical pore structure was synthesized, for the first time using this method.

    It was found that a variation in the heptane concentration, in combination with a long stirring time, yields a transition between fiber and sheet morphologies. Both morphologies consist of crystallites, which for the fibers are joined end to end, while for the sheets they are attached side by side such that the pores are accessible from the sheet surface. The crystallites can be separated to a rod morphology by decreasing the stirring time and tuning the HCl concentration, and it was seen that these rods are formed within 5 min of static time, even though the pore size and unit cell parameters were evolving for another 30 min. Further studies of the effects of heptane showed that the shape and mesoscopic parameters of the rods are affected by the heptane concentration, up to a value where the micelles are fully saturated with heptane. It was also observed that the particle width increases with decreasing NH4F concentration, independent of heptane amount, and a platelet morphology can be formed. The formation time of the particles decrease with decreasing NH4F, and the growth mechanism for platelets was further studied. The pore sizes for various morphologies were altered by e.g. variations in the hydrothermal treatment conditions, or the method for removing the surfactants.

    The separated particles can be attached to substrates, either during the particle synthesis or by post grafting prior to calcination. The film formation during the one-pot-synthesis was studied and a formation mechanism including nucleation of elongated micelles on the substrate was suggested. During the post grafting film synthesis, the medium in which the particles are dispersed, as well as functionalization of both particle and substrate are crucial for the post grafting process. The pores are easily accessible independent of the method, even though they are aligned parallel to the substrate when the one-pot-method is used, while post grafting gives a perpendicular pore orientation.

    In summary, this work aims to give an understanding for the formation of the synthesized material, and how to tune the material properties by alterations in parameter space. Successful syntheses of four different particle morphologies and two new types of films were performed, and the pore size could easily be tuned by various methods.

    List of papers
    1. Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores
    Open this publication in new window or tab >>Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores
    2009 (English)In: Materials Letters, ISSN 0167-577X, Vol. 63, no 24-25, p. 2129-2131Article in journal (Refereed) Published
    Abstract [en]

    Mesoporous silica SBA-15 in the form of 10-30 μm sized sheets with unusually large ordered pores has been synthesized using heptane as a cosolvent in the presence of NH4F. The resulting morphology of 400 nm thick sheets that contain easily accessed, hexagonally arranged, 18 nm sized pores running parallel to sheet normal has not been previously reported. The material has a BET surface area of 541 m2/g, large pore volume of 1.69 cm3/g and ordered mesopore structure with a narrow pore size distribution around 18 nm. A mechanism for sheet formation based on heptane droplets acting as sites for self assembling of silica crystallites is suggested.

    Keywords
    Large pore; Mesoporous silica; SBA-15; Sheet
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-21193 (URN)10.1016/j.matlet.2009.07.013 (DOI)
    Note
    Original Publication: Emma Johansson, Jose Manuel Cordoba and Magnus Odén, Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores, 2009, Materials Letters, (63), 24-25, 2129-2131. http://dx.doi.org/10.1016/j.matlet.2009.07.013 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2009-09-30 Created: 2009-09-30 Last updated: 2013-10-22
    2. Synthesis of hollow silica spheres SBA-16 with large-pore diameter
    Open this publication in new window or tab >>Synthesis of hollow silica spheres SBA-16 with large-pore diameter
    2011 (English)In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 65, no 7, p. 1066-1068Article in journal (Refereed) Published
    Abstract [en]

    Hollow silica SBA-16 spheres with cubic ordered mesoporous shells were synthesized by an emulsion-templating method, using Pluronic F127 as a structure-directing agent. tetraethyl orthosilicateas as a silica source and heptane as a cosolvent in the presence of NH4F. The size of these spheres is in the range of 10 to 30 mu m. The shell is about 700 nm thick and consists of large pores, similar to 9 nm in diameter, arranged in a cubic order. After calcination, the spheres maintain their mesoporosity and show a high surface area of 822 m(2)/g. The formation mechanism of the silica hollow spheres is discussed.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2011
    Keywords
    Mesoporous silica, SBA-16, Hollow spheres, Large pore, F127
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67554 (URN)10.1016/j.matlet.2011.01.035 (DOI)000289021700002 ()
    Available from: 2011-04-18 Created: 2011-04-18 Last updated: 2017-12-11Bibliographically approved
    3. The effects on pore size and particle morphology of heptane additions to the synthesis of mesoporous silica SBA-15
    Open this publication in new window or tab >>The effects on pore size and particle morphology of heptane additions to the synthesis of mesoporous silica SBA-15
    2010 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 133, no 01-Mar, p. 66-74Article in journal (Refereed) Published
    Abstract [en]

    The effect of heptane on the particle morphology and pore size in the synthesis of SBA-15 is presented. Heptane in the presence of NH4F works as a pore swelling agent, resulting in 13-18 nm sized pores in 400 nm long and 200-1000 nm wide crystallites. The pores are hexagonally arranged and run through the crystallites. Increasing the heptane to P123 molar ratio changes the morphology of SBA-15 from fibers to sheets when the crystallites rearrange during the synthesis. The pore order in the sheets is controlled by changing the molar ratio of water to P123. The surface areas of these materials are 500-800 m(2)/g with pore volumes of 1.2-1.7 cm(3)/g. The sheets have accessible pores with a size of 18 nm running parallel to the sheet normal, which makes them suitable for membranes.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2010
    Keywords
    SBA-15; Morphology; Heptane; H2O2; Sheet
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-58290 (URN)10.1016/j.micromeso.2010.04.016 (DOI)000279061000009 ()
    Available from: 2010-08-10 Created: 2010-08-09 Last updated: 2017-12-12
    4. Rapid Synthesis of SBA-15 Rods with Variable Lengths, Widths, and Tunable Large Pores
    Open this publication in new window or tab >>Rapid Synthesis of SBA-15 Rods with Variable Lengths, Widths, and Tunable Large Pores
    2011 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 8, p. 4994-4999Article in journal (Refereed) Published
    Abstract [en]

    Dispersed SBA-15 rods have been synthesized with varying lengths, widths, and pore sizes in a low-temperature synthesis in the presence of heptane and NH4F. The pore size of the material can systematically be varied between 11 and 17 nm using different hydrothermal treatment times And/or temperatures. The particle length (400-600 nm) and width (100-400 nm) were tuned by varying the HCl concentration. All the synthesized materials possess a large surface area of 400-600 m(2)/g And a pore volume of 1.05-1.30 cm(3). A, mechanism for the effect of the HCl concentration on the particle morphology is suggested. Furthermore, it is shown that the reaction time an be decreased to 1 h, with well-retained pore size and morphology. This work has resulted in SBA-15 rods with the largest pore size reported for this morphology.

    Place, publisher, year, edition, pages
    ACS American Chemical Society, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67831 (URN)10.1021/la104864d (DOI)000289321000091 ()
    Available from: 2011-04-29 Created: 2011-04-29 Last updated: 2017-12-11Bibliographically approved
    5. Tuning the shape of mesoporous silica particles by alterations in parameter space: from rods to platelets
    Open this publication in new window or tab >>Tuning the shape of mesoporous silica particles by alterations in parameter space: from rods to platelets
    2013 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, no 44, p. 13551-13561Article in journal (Refereed) Published
    Abstract [en]

    The knowledge of how to control the pore size and morphology of separated mesoporous silica particles is crucial for optimizing their performance in applications, such as molecular sieves and drug delivery systems. In this work, we have systematically studied the effects of various synthesis parameters to gain a deeper understanding of how particle morphologies can be altered. It was found that the morphology for isolated particles of SBA-15 type, with unusually short and wide pores, could be altered from rods to platelets by variations in the NH4F concentration. The pore length is nearly constant (similar to 300 nm) for the different morphologies, but the particle width is increasing from 200 nm to >3 mu m when decreasing the amount of NH4F, and the pore size can be tuned between 10 and 13 nm. Furthermore, other synthesis parameters such as heptane concentration, pH, silica precursor, and additions of ions have also been studied. The trend regarding particle width is independent of heptane concentration, at the same time as heptane increases the particle length up to a plateau value of similar to 500 nm. In all, parameters controlling particle width, length, and pore size have been separated in order to evaluate their function in the particle formation. Additionally, it was found that the formation time of the particles is strongly affected by the fluoride ion concentration, and a mechanism for particle formation for this system, where micelles transform from a foam, to multilamellar vesicles, and finally to cylindrical micelles, is suggested.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2013
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-99859 (URN)10.1021/la403201v (DOI)000326711200029 ()
    Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2017-12-06Bibliographically approved
    6. Single-pot synthesis of ordered mesoporous silica films with unique controllable morphology
    Open this publication in new window or tab >>Single-pot synthesis of ordered mesoporous silica films with unique controllable morphology
    2014 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 413, p. 1-7Article in journal (Refereed) Published
    Abstract [en]

    Mesoporous silica films consisting of a monolayer of separated SBA-15 particles with unusually wide and short pores grown on silicon wafers have been fabricated in a simple single-pot-synthesis, and the formation of the films has been studied. A recipe for synthesizing mesoporous silica rods with the addition of heptane and NH4F at low temperature was used and substrates were added to the synthesis solution during the reaction. The films are ∼90 nm thick, have a pore size of 10.7–13.9 nm depending on the hydrothermal treatment time and temperature, and a pore length of 200–400 nm. All pores are parallel to the substrate, open, and easy to access, making them suitable for applications such as catalyst hosts and gas separation. The growth of the films is closely correlated to the evolution of the mesoporous silica particles. Here, we have studied the time for adding substrates to the synthesis solution, the evolution of the films with time during formation, and the effect of hydrothermal treatment. It was found that the substrates should be added within 30–60 s after turning off the stirring and the films are formed within 10 min after addition to the synthesis solution. The study has yielded a new route for synthesizing mesoporous silica films with a unique morphology.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    SBA-15; Mesoporous silica; Large pore; Films; Rods; Film growth; Particle formation
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-99856 (URN)10.1016/j.jcis.2013.09.023 (DOI)000327168800001 ()
    Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2017-12-06Bibliographically approved
    7. Grafting mesoporous silica particles to substrates: a method for synthesizing mesoporous films with cylindrical pores perpendicular to the substrate
    Open this publication in new window or tab >>Grafting mesoporous silica particles to substrates: a method for synthesizing mesoporous films with cylindrical pores perpendicular to the substrate
    2013 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    A method for synthesizing mesoporous silica films with cylindrical pores perpendicular to the substrate has been developed. The films consist of SBA-15 platelets that are grafted on glass substrates. The grafting is studied in terms of parameters such as pH, substrate functionalization, salt additions, time for TEOS prehydrolysis, and calcination. The best coverage of particles on the substrate was achieved for a low pH in combination with OTS-treated glass substrate. Furthermore, the prehydrolysis time of the TEOS was found to be a key parameter in order to bind the particles to the substrate. These porous films have potential in applications such as catalysis, drug delivery, and as a template for nanoparticle or nanorod, growth.

    Keywords
    Mesoporous silica films, platelets, particle functionalization, substrate functionalization, pH, salt
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-99857 (URN)
    Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2013-10-22Bibliographically approved
  • 8.
    Björk, Emma M.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Grafting mesoporous silica particles to substrates: a method for synthesizing mesoporous films with cylindrical pores perpendicular to the substrate2013Manuscript (preprint) (Other academic)
    Abstract [en]

    A method for synthesizing mesoporous silica films with cylindrical pores perpendicular to the substrate has been developed. The films consist of SBA-15 platelets that are grafted on glass substrates. The grafting is studied in terms of parameters such as pH, substrate functionalization, salt additions, time for TEOS prehydrolysis, and calcination. The best coverage of particles on the substrate was achieved for a low pH in combination with OTS-treated glass substrate. Furthermore, the prehydrolysis time of the TEOS was found to be a key parameter in order to bind the particles to the substrate. These porous films have potential in applications such as catalysis, drug delivery, and as a template for nanoparticle or nanorod, growth.

  • 9.
    Björk, Emma M.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Single-pot synthesis of ordered mesoporous silica films with unique controllable morphology2014In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 413, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Mesoporous silica films consisting of a monolayer of separated SBA-15 particles with unusually wide and short pores grown on silicon wafers have been fabricated in a simple single-pot-synthesis, and the formation of the films has been studied. A recipe for synthesizing mesoporous silica rods with the addition of heptane and NH4F at low temperature was used and substrates were added to the synthesis solution during the reaction. The films are ∼90 nm thick, have a pore size of 10.7–13.9 nm depending on the hydrothermal treatment time and temperature, and a pore length of 200–400 nm. All pores are parallel to the substrate, open, and easy to access, making them suitable for applications such as catalyst hosts and gas separation. The growth of the films is closely correlated to the evolution of the mesoporous silica particles. Here, we have studied the time for adding substrates to the synthesis solution, the evolution of the films with time during formation, and the effect of hydrothermal treatment. It was found that the substrates should be added within 30–60 s after turning off the stirring and the films are formed within 10 min after addition to the synthesis solution. The study has yielded a new route for synthesizing mesoporous silica films with a unique morphology.

  • 10.
    Björk, Emma M.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Tuning the shape of mesoporous silica particles by alterations in parameter space: from rods to platelets2013In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, no 44, p. 13551-13561Article in journal (Refereed)
    Abstract [en]

    The knowledge of how to control the pore size and morphology of separated mesoporous silica particles is crucial for optimizing their performance in applications, such as molecular sieves and drug delivery systems. In this work, we have systematically studied the effects of various synthesis parameters to gain a deeper understanding of how particle morphologies can be altered. It was found that the morphology for isolated particles of SBA-15 type, with unusually short and wide pores, could be altered from rods to platelets by variations in the NH4F concentration. The pore length is nearly constant (similar to 300 nm) for the different morphologies, but the particle width is increasing from 200 nm to >3 mu m when decreasing the amount of NH4F, and the pore size can be tuned between 10 and 13 nm. Furthermore, other synthesis parameters such as heptane concentration, pH, silica precursor, and additions of ions have also been studied. The trend regarding particle width is independent of heptane concentration, at the same time as heptane increases the particle length up to a plateau value of similar to 500 nm. In all, parameters controlling particle width, length, and pore size have been separated in order to evaluate their function in the particle formation. Additionally, it was found that the formation time of the particles is strongly affected by the fluoride ion concentration, and a mechanism for particle formation for this system, where micelles transform from a foam, to multilamellar vesicles, and finally to cylindrical micelles, is suggested.

  • 11.
    Björk, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. University of Nacl Rio Cuarto, Argentina.
    Militello, Maria P.
    University of Nacl Rio Cuarto, Argentina.
    Tamborini, Luciano H.
    University of Nacl Rio Cuarto, Argentina.
    Coneo Rodriguez, Rusbel
    University of Nacl Rio Cuarto, Argentina.
    Planes, Gabriel A.
    University of Nacl Rio Cuarto, Argentina.
    Acevedo, Diego F.
    University of Nacl Rio Cuarto, Argentina; University of Nacl Rio Cuarto, Argentina.
    Sergio Moreno, M.
    Consejo Nacl Invest Cient and Tecn, Argentina.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Barbero, Cesar A.
    University of Nacl Rio Cuarto, Argentina.
    Mesoporous silica and carbon based catalysts for esterification and biodiesel fabrication-The effect of matrix surface composition and porosity2017In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 533, p. 49-58Article in journal (Refereed)
    Abstract [en]

    The effects of catalyst matrix porosity composition on the catalytic performance have been studied using sulfonated mesoporous SBA-15 silica. The matrix was sulfonated with three different methods grafting, in situ oxidation, and carbon infiltration. Additionally, unordered sulfonated mesoporous carbon, and the commercial catalysts Amberlite IR-120 and Nafion 117 were tested. The catalytic performance was evaluated in a Fischer esterification using acetic acid and ethanol, as well as in a transesterification of triglycerides (sunflower oil) and ethanol to produce biodiesel. The study shows that for long carbon chains, the effective wetting of the porous catalyst matrix by the reactants is most important for the catalytic efficiency, while for shorter carbon chain, the mass transport of the reagents trough the porous structure is more important. The catalysts were analysed using electron microscopy and physisorption. The study shows that the reactions are faster with carbon infiltrated materials than the silica materials due to a higher concentration of sulfonic groups linked to the carbon. The in situ functionalized SBA-15 is a more efficient catalyst compared to the post grafted one. All the synthesized catalysts outperform the commercial ones in both reactions in terms of conversion. (C) 2017 Elsevier B.V. All rights reserved.

  • 12.
    Björk, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Ulm, Germany.
    Mäkie, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Rogström, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Atakan, Aylin
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Schell, Norbert
    Helmholtz Zentrum Geesthacht, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Formation of block-copolymer-templated mesoporous silica2018In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 521, p. 183-189Article in journal (Refereed)
    Abstract [en]

    In situ attenuated total reflectance Fourier transform infrared spectroscopy is used to monitor the chemical evolution of the mesoporous silica SBA-15 from hydrolysis of the silica precursor to final silica condensation after the particle formation. Two silica precursors, tetraethyl orthosilicate (TEOS) or sodium metasilicate (SMS) were used, and the effects of additive (heptane and NH4F) concentrations were studied. Five formation stages are identified when TEOS is used as the precursor. The fourth stage correlates with the appearance and evolution of diffraction peaks recorded using in situ small angle X-ray diffraction. Details of the formed silica matrix are observed, e.g. the ratio between six-fold cyclic silica rings and linear bonding increases with the NH4F concentration. The TEOS hydrolysis time is independent of the NH4F concentration for small amounts of heptane, but is affected by the size of the emulsion droplets when the heptane amount increases. Polymerization and condensation rates of both silica precursors are affected by the salt concentration. Materials synthesized using SMS form significantly faster compared to TEOS-materials due to the pre-hydrolysis of the precursor. The study provides detailed insights into how the composition of the synthesis solution affects the chemical evolution and micellar aggregation during formation of mesoporous silica. (C) 2018 Elsevier Inc. All rights reserved.

    The full text will be freely available from 2020-03-13 13:33
  • 13.
    Cordoba Gallego, Jose Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Ballem, Mohamed
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Growth of single crystalline dendritic Li(2)SiO(3) arrays from LiNO(3) and mesoporous SiO(2)2011In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 184, no 7, p. 1735-1739Article in journal (Refereed)
    Abstract [en]

    A solution based wet chemistry approach has been developed for synthesizing Li(2)SiO(3) using LiNO(3) and mesoporous silica as starting materials at 550 degrees C. A reaction path where NO and O(2) are formed as side-products is proposed. The crystals synthesized exhibit dendritic growth where the as-prepared nanodendrite is a typical 1-fold nanodendrite composed of one several microns long and some tenth of nanometers wide trunk with small branches, which are several hundreds of nanometers long and up to 70 nm in diameter. The effect of the structure of the mesoporous silica for the final morphology is discussed.

  • 14.
    Frodelius, Jenny
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Johansson, Emma M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Córdoba, José M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Annealing of thermally sprayed Ti2AlC coatings2011In: INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, ISSN 1546-542X, Vol. 8, no 1, p. 74-84Article in journal (Refereed)
    Abstract [en]

    Phase transformations during annealing of coatings sprayed with the High Velocity Oxy-Fuel technique using Ti2AlC powder have been investigated by in-situ x-ray diffraction. The asdeposited coatings, consisting of Ti2AlC, Ti3AlC2, TiC, Ti-Al, and oxides, are stable up to 500 °C. Ti3AlC2 forms above 550 °C and Ti2AlC forms above 700 °C by intercalation of Al into TiCx. For temperatures between 900 and 1100 °C, Ti3AlC2 and Ti2AlC decompose by losing Al to the surrounding matrix resulting in TiCx, and Al2O3. The thermal expansion coefficient between ambient and 700°C is 11.9·10-6 K-1. The thermal diffusivity at room temperature is 1.9·10-6 m2/s.

  • 15.
    Gustafsson, Hanna
    et al.
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Johannsson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Barrabino, Albert
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Holmberg, Krister
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Immobilization of lipase from Mucor miehei and Rhizopus oryzae into mesoporous silica - The effect of varied particle size and morphology2012In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 100, p. 22-30Article in journal (Refereed)
    Abstract [en]

    Immobilization of enzymes usually improves the recyclability and stability and can sometimes also improve the activity compared to enzymes free in solution. Mesoporous silica is a widely studied material as host for immobilized enzymes because of its large internal surface area and tunable pores. It has previously been shown that the pore size is critical both for the loading capacity and for the enzymatic activity; however, less focus has been given to the influence of the particle size. In this work the effect of particle size and particle morphology on the immobilization of lipase from Mucor miehei and Rhizopus oryzae have been investigated. Three kinds of mesoporous silica, all with 9 nm pores but with varying particle size (1000 nm, 300 nm and 40 nm) have been synthesized and were used as host for the lipases. The two lipases, which have the same molecular size but widely different isoelectric points, were immobilized into the silica particles at varied pH values within the interval 5 to 8. The 300 nm particles were proven to be the most suitable carrier with respect to specific activity for both enzymes. The lipase from Mucor miehei was more than four times as active when immobilized at pH 8 compared to free in solution whereas the difference was less pronounced for the Rhizopus oryzae lipase.

  • 16.
    Jeenpadiphat, Sirima
    et al.
    Chulalongkorn University, Thailand.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Nuntasri Tungasmita, Duangamol
    Chulalongkorn University, Thailand.
    Propylsulfonic acid functionalized mesoporous silica catalysts for esterification of fatty acids2015In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 410, p. 253-259Article in journal (Refereed)
    Abstract [en]

    The catalytic properties of 3 types of mesoporous silica SBA-15 (rope, rod and fiber), with 9.2 nm or 12.1 nm large mesopores, were examined with respect to their morphology and pore size. Commercially available Amberlyst-15 and the small pore sized MCM-41 were used for comparison. The catalysts were prepared by functionalization of the silica supports with propylsulfonic acid (Pr-SO3H) using postsynthesis grafting with 3 -mercaptopropyltrimethoxysilane as a propyl-thiol precursor. All materials remained in a well-ordered hexagonal mesoporous structure after Pr-SO3H functionalization. The performance of the Pr-SO3H-functionalized mesoporous silicas was evaluated in terms of their catalytic activity in the esterification of oleic acid with short (methanol) and long (glycerol) chain alcohols, i.e., to test the effect of the pore size on the substrate conversion and product yield. The synthesized catalysts were highly active and the product composition could be tuned by selective choice of the mesopore size. The Pr-SO3H-functionalized rope-shaped SBA-15 gave the highest catalytic activity (in terms of the highest methyl oleate and triglyceride yields and oleic acid conversion level), which was higher than that obtained with the commercial Amberlyst-15 catalyst. A high acid amount, large specific surface area and a suitable pore size are the likely reasons for the high yield gained by Pr-SO3H-functionalized rope-shaped SBA-15 silica. (C) 2015 Elsevier B.V. All rights reserved.

  • 17.
    Johansson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Ballem, Mohamed
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Rapid Synthesis of SBA-15 Rods with Variable Lengths, Widths, and Tunable Large Pores2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 8, p. 4994-4999Article in journal (Refereed)
    Abstract [en]

    Dispersed SBA-15 rods have been synthesized with varying lengths, widths, and pore sizes in a low-temperature synthesis in the presence of heptane and NH4F. The pore size of the material can systematically be varied between 11 and 17 nm using different hydrothermal treatment times And/or temperatures. The particle length (400-600 nm) and width (100-400 nm) were tuned by varying the HCl concentration. All the synthesized materials possess a large surface area of 400-600 m(2)/g And a pore volume of 1.05-1.30 cm(3). A, mechanism for the effect of the HCl concentration on the particle morphology is suggested. Furthermore, it is shown that the reaction time an be decreased to 1 h, with well-retained pore size and morphology. This work has resulted in SBA-15 rods with the largest pore size reported for this morphology.

  • 18.
    Johansson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    The effects on pore size and particle morphology of heptane additions to the synthesis of mesoporous silica SBA-152010In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 133, no 01-Mar, p. 66-74Article in journal (Refereed)
    Abstract [en]

    The effect of heptane on the particle morphology and pore size in the synthesis of SBA-15 is presented. Heptane in the presence of NH4F works as a pore swelling agent, resulting in 13-18 nm sized pores in 400 nm long and 200-1000 nm wide crystallites. The pores are hexagonally arranged and run through the crystallites. Increasing the heptane to P123 molar ratio changes the morphology of SBA-15 from fibers to sheets when the crystallites rearrange during the synthesis. The pore order in the sheets is controlled by changing the molar ratio of water to P123. The surface areas of these materials are 500-800 m(2)/g with pore volumes of 1.2-1.7 cm(3)/g. The sheets have accessible pores with a size of 18 nm running parallel to the sheet normal, which makes them suitable for membranes.

  • 19.
    Johansson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores2009In: Materials Letters, ISSN 0167-577X, Vol. 63, no 24-25, p. 2129-2131Article in journal (Refereed)
    Abstract [en]

    Mesoporous silica SBA-15 in the form of 10-30 μm sized sheets with unusually large ordered pores has been synthesized using heptane as a cosolvent in the presence of NH4F. The resulting morphology of 400 nm thick sheets that contain easily accessed, hexagonally arranged, 18 nm sized pores running parallel to sheet normal has not been previously reported. The material has a BET surface area of 541 m2/g, large pore volume of 1.69 cm3/g and ordered mesopore structure with a narrow pore size distribution around 18 nm. A mechanism for sheet formation based on heptane droplets acting as sites for self assembling of silica crystallites is suggested.

  • 20.
    Johansson, Emma M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Controlling the Pore Size and Morphology of Mesoporous Silica2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mesoporous silica with a hexagonally ordered pore structure (SBA-15) has been synthesized. Through variations in the synthesis conditions several morphologies, such as fibers, sheets and separate rods, have been realized. Furthermore, additions of heptane and NH4F make it possible to synthesize SBA-15 with pores as large as 18 nm in the sheet morphology. Mechanisms for the formation of different morphologies have been suggested. In the case of fibers and sheets, the amount of heptane present during the synthesis determines the final morphology. For low concentrations, the heptane enters the micelles and increases the pore size while the particles (crystallites) attaches to each other end to end. When the heptane concentration increases, the heptane droplets increase in size, and above a critical droplet size the crystallites attach with one short end towards the droplet, forming the sheet morphology. The crystallites can also be separated. This is the case of the rod morphology. The separation is performed by shortening the stirring time and increasing the HCl concentration. The increased amount of HCl increases the hydration rate of the silica precursor, which can be used to control the thickness and length of the rods. Furthermore, the reaction time has been decreased from 20 h for all morphologies to less than 4 hours. The materials have been characterized with nitrogen sorption, electron microscopy and x-ray diffraction. Also, thermogravimetric analysis and fourier transformed infrared spectroscopy have been used for studying the removal of surfactants.

    List of papers
    1. Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores
    Open this publication in new window or tab >>Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores
    2009 (English)In: Materials Letters, ISSN 0167-577X, Vol. 63, no 24-25, p. 2129-2131Article in journal (Refereed) Published
    Abstract [en]

    Mesoporous silica SBA-15 in the form of 10-30 μm sized sheets with unusually large ordered pores has been synthesized using heptane as a cosolvent in the presence of NH4F. The resulting morphology of 400 nm thick sheets that contain easily accessed, hexagonally arranged, 18 nm sized pores running parallel to sheet normal has not been previously reported. The material has a BET surface area of 541 m2/g, large pore volume of 1.69 cm3/g and ordered mesopore structure with a narrow pore size distribution around 18 nm. A mechanism for sheet formation based on heptane droplets acting as sites for self assembling of silica crystallites is suggested.

    Keywords
    Large pore; Mesoporous silica; SBA-15; Sheet
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-21193 (URN)10.1016/j.matlet.2009.07.013 (DOI)
    Note
    Original Publication: Emma Johansson, Jose Manuel Cordoba and Magnus Odén, Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores, 2009, Materials Letters, (63), 24-25, 2129-2131. http://dx.doi.org/10.1016/j.matlet.2009.07.013 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2009-09-30 Created: 2009-09-30 Last updated: 2013-10-22
    2. The effects on pore size and particle morphology of heptane additions to the synthesis of mesoporous silica SBA-15
    Open this publication in new window or tab >>The effects on pore size and particle morphology of heptane additions to the synthesis of mesoporous silica SBA-15
    2010 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 133, no 01-Mar, p. 66-74Article in journal (Refereed) Published
    Abstract [en]

    The effect of heptane on the particle morphology and pore size in the synthesis of SBA-15 is presented. Heptane in the presence of NH4F works as a pore swelling agent, resulting in 13-18 nm sized pores in 400 nm long and 200-1000 nm wide crystallites. The pores are hexagonally arranged and run through the crystallites. Increasing the heptane to P123 molar ratio changes the morphology of SBA-15 from fibers to sheets when the crystallites rearrange during the synthesis. The pore order in the sheets is controlled by changing the molar ratio of water to P123. The surface areas of these materials are 500-800 m(2)/g with pore volumes of 1.2-1.7 cm(3)/g. The sheets have accessible pores with a size of 18 nm running parallel to the sheet normal, which makes them suitable for membranes.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2010
    Keywords
    SBA-15; Morphology; Heptane; H2O2; Sheet
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-58290 (URN)10.1016/j.micromeso.2010.04.016 (DOI)000279061000009 ()
    Available from: 2010-08-10 Created: 2010-08-09 Last updated: 2017-12-12
    3. Rapid Synthesis of SBA-15 Rods with Variable Lengths, Widths, and Tunable Large Pores
    Open this publication in new window or tab >>Rapid Synthesis of SBA-15 Rods with Variable Lengths, Widths, and Tunable Large Pores
    2011 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 8, p. 4994-4999Article in journal (Refereed) Published
    Abstract [en]

    Dispersed SBA-15 rods have been synthesized with varying lengths, widths, and pore sizes in a low-temperature synthesis in the presence of heptane and NH4F. The pore size of the material can systematically be varied between 11 and 17 nm using different hydrothermal treatment times And/or temperatures. The particle length (400-600 nm) and width (100-400 nm) were tuned by varying the HCl concentration. All the synthesized materials possess a large surface area of 400-600 m(2)/g And a pore volume of 1.05-1.30 cm(3). A, mechanism for the effect of the HCl concentration on the particle morphology is suggested. Furthermore, it is shown that the reaction time an be decreased to 1 h, with well-retained pore size and morphology. This work has resulted in SBA-15 rods with the largest pore size reported for this morphology.

    Place, publisher, year, edition, pages
    ACS American Chemical Society, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67831 (URN)10.1021/la104864d (DOI)000289321000091 ()
    Available from: 2011-04-29 Created: 2011-04-29 Last updated: 2017-12-11Bibliographically approved
  • 21.
    Mutschler, Anna
    et al.
    Ulm Univ, Germany.
    Stock, Vivian
    Ulm Univ, Germany.
    Ebert, Lena
    Ulm Univ, Germany.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Ulm Univ, Germany.
    Leopold, Kerstin
    Ulm Univ, Germany.
    Linden, Mika
    Ulm Univ, Germany.
    Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water2019In: NANOMATERIALS, ISSN 2079-4991, Vol. 9, no 1, article id 35Article in journal (Refereed)
    Abstract [en]

    Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination using a novel thin film sampling stick for passive sampling based on gold nanoparticles. The nanoparticles supported on a silicon wafer and further covered with a thin layer of mesoporous silica. The mesoporous silica layer is acting as a protection layer preventing gold desorption upon exposure to water. The gold nanoparticles are created by thermal treatment of a homogenous gold layer on silicon wafer prepared by vacuum evaporation. This gold-covered substrate is subsequently covered by a layer of mesoporous silica through dip-coating. Dissolved mercury ions are extracted from a water sample, e.g., river water, by incorporation into the gold matrix in a diffusion-controlled manner. Thus, the amount of mercury accumulated during sampling depends on the mercury concentration of the water sample, the accumulation time, as well as the size of the substrate. Therefore, the experimental conditions can be chosen to fit any given mercury concentration level without loss of sensitivity. Determination of the mercury amount collected on the stick is performed after thermal desorption of mercury in the gas phase using atomic fluorescence spectrometry. Furthermore, the substrates can be re-used several tens of times without any loss of performance, and the batch-to-batch variations are minimal. Therefore, the nanogold-mesoporous silica sampling substrates allow for highly sensitive, simple, and reagent-free determination of mercury trace concentrations in waters, which should also be applicable for on-site analysis. Successful validation of the method was shown by measurement of mercury concentration in the certified reference material ORMS-5, a river water.

  • 22.
    Paul, Biplab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Björk, Emma M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Kumar, Aparabal
    Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, India.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics2018In: ACS applied energy materials, ISSN 2574-0962, Vol. 1, no 5, p. 2261-2268Article in journal (Refereed)
    Abstract [en]

    The development of high-performance and transferable thin-film thermoelectric materials is important for low-power applications, e.g., to power wearable electronics, and for on-chip cooling. Nanoporous films offer an opportunity to improve thermoelectric performance by selectively scattering phonons without affecting electronic transport. Here, we report the growth of nanoporous Ca3Co4O9 thin films by a sequential sputtering-annealing method. Ca3Co4O9 is promising for its high Seebeck coefficient and good electrical conductivity and important for its nontoxicity, low cost, and abundance of its constituent raw materials. To grow nanoporous films, multilayered CaO/CoO films were deposited on sapphire and mica substrates by rf-magnetron reactive sputtering from elemental Ca and Co targets, followed by annealing at 700 C to form the final phase of Ca3Co4O9. This phase transformation is accompanied by a volume contraction causing formation of nanopores in the film. The thermoelectric propoperties of the nanoporous Ca3Co4O9 films can be altered by controlling the porosity. The lowest electrical resistivity is ~7 mO cm, yielding a power factor of 2.32 × 10-4 Wm-1K-2 near room temperature. Furthermore, the films are transferable from the primary mica substrates to other arbitrary polymer platforms by simple dry transfer, which opens an opportunity of low-temperature use these materials.

  • 23.
    Sen Karaman, D.
    et al.
    Abo Akad University, Finland; Abo Akad University, Finland.
    Sarwar, S.
    Bose Institute, India.
    Desai, D.
    Abo Akad University, Finland.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Chakrabarti, P.
    Bose Institute, India.
    Rosenholm, J. M.
    Abo Akad University, Finland.
    Chakraborti, S.
    Bose Institute, India; Indiana University, IN USA.
    Shape engineering boosts antibacterial activity of chitosan coated mesoporous silica nanoparticle doped with silver: a mechanistic investigation2016In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 4, no 19, p. 3292-3304Article in journal (Refereed)
    Abstract [en]

    In this study, mesoporous silica nanoparticles (MSPs) of different size and shape were developed, and their surface coatings were utilized to study their differential effects in enhancing antibacterial activity. In brief, MSPs with three different aspect ratios (1, 2 and 4) were prepared, doped with silver ions and finally coated with the polymer chitosan. Both Gram-positive and Gram-negative bacteria were treated with the MSPs. Results indicate that silver ion doped and chitosan coated MSPs with the aspect ratio of 4 (Cht/MSP4:Ag+) have the highest antimicrobial activity among the prepared series. Further studies revealed that Cht/MSP4:Ag+ was most effective against Escherichia coli (E.coli) and least effective against Vibrio cholerae (V. cholerae). To investigate the detailed inhibition mechanism of the MSPs, the interaction of the nanoparticles with E.coli membranes and its intracellular DNA was assessed using various spectroscopic and imaging-based techniques. Furthermore, to increase the efficiency of the MSPs, a combinatorial antibacterial strategy was also explored, where nanoparticles, in combination with kanamycin (antibiotic), were used against Vibrio Cholerae (V. cholerae). Toxicity screening of these on MSPs was conducted on Caco-2 cells, and the results show that the dose used for antibacterial screening is below the limit of the toxicity threshold. Our findings show that both shape and surface engineering contribute positively towards killing bacteria, and the newly developed silver ion-doped and chitosan-coated MSPs have good potential as antimicrobial nanomaterials.

  • 24.
    Sen Karaman, Didem
    et al.
    Abo Akad University, Finland .
    Desai, Diti
    Abo Akad University, Finland Maharaja Sayajirao University of Baroda, India .
    Senthilkumar, Rajendran
    Abo Akad University, Finland .
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Ratts, Natalie
    Abo Akad University, Finland Abo Akad University, Finland Abo Akad University, Finland University of Turku, Finland .
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    E Eriksson, John
    Abo Akad University, Finland .
    Sahlgren, Cecilia
    Abo Akad University, Finland Abo Akad University, Finland University of Turku, Finland .
    Toivola, Diana M.
    Abo Akad University, Finland Turku Centre Disease Modeling, Finland .
    Rosenholm, Jessica M.
    Abo Akad University, Finland .
    Shape engineering vs organic modification of inorganic nanoparticles as a tool for enhancing cellular internalization2012In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 7, no 358Article in journal (Refereed)
    Abstract [en]

    In nanomedicine, physicochemical properties of the nanocarrier affect the nanoparticles pharmacokinetics and biodistribution, which are also decisive for the passive targeting and nonspecific cellular uptake of nanoparticles. Size and surface charge are, consequently, two main determining factors in nanomedicine applications. Another important parameter which has received much less attention is the morphology (shape) of the nanocarrier. In order to investigate the morphology effect on the extent of cellular internalization, two similarly sized but differently shaped rod-like and spherical mesoporous silica nanoparticles were synthesized, characterized and functionalized to yield different surface charges. The uptake in two different cancer cell lines was investigated as a function of particle shape, coating (organic modification), surface charge and dose. According to the presented results, particle morphology is a decisive property regardless of both the different surface charges and doses tested, whereby rod-like particles internalized more efficiently in both cell lines. At lower doses whereby the shape-induced advantage is less dominant, charge-induced effects can, however, be used to fine-tune the cellular uptake as a prospective secondary uptake regulator for tight dose control in nanoparticle-based drug formulations.

  • 25.
    Senthilkumar, Rajendran
    et al.
    Abo Akad University, Finland.
    Sen Karaman, Didem
    Abo Akad University, Finland.
    Paul, Preethy
    Abo Akad University, Finland.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Eriksson, John E.
    Abo Akad University, Finland.
    Rosenholm, Jessica M.
    Abo Akad University, Finland.
    Targeted delivery of a novel anticancer compound anisomelic acid using chitosan-coated porous silica nanorods for enhancing the apoptotic effect2015In: BIOMATERIALS SCIENCE, ISSN 2047-4830, Vol. 3, no 1, p. 103-111Article in journal (Refereed)
    Abstract [en]

    Targeted cancer therapies are currently a strong focus in biomedical research. The most common approach is to use nanocarrier-based targeting to specifically deliver conventional anticancer drugs to enhance their therapeutic efficacy, increase bioavailability, and decrease the side-effects on normal cells. A step further towards higher specificity and efficacy would be to employ specific novel drugs along with specific nanocarrier-based targeting. Our recent studies have demonstrated that a plant-derived diterpenoid compound, anisomelic acid (AA), induces apoptosis in cervical cancer cells. In this work, we describe the development of a folic acid (FA)-targeted AA delivery system using chitosan-coated rod-shaped mesoporous silica particles (Chitosan-NR-MSP). The cellular internalization and uptake enhancement of the FA-Chitosan-NR-MSP towards cancerous folate receptor (FR)-positive (SiHa and HeLa) and/or normal FR-negative (HEK 293) cells were assessed, which indicated that the intracellular uptake of FA-conjugated Chitosan-NR-MSP was more target-specific. Furthermore, the induction of apoptosis by AA-loaded chitosan-coated rod-shaped particles on SiHa cells was studied. By employing caspase-3 activation and PARP cleavage as measure of apoptosis, the FA-particle mediated AA treatment was clearly more effective, significantly enhancing apoptosis in comparison to non-targeted Chitosan-NR-MSP or free AA in SiHa cells, suggesting that the FA-Chitosan-NR-MSPs can be potentially utilized as a drug delivery system for cervical cancer treatment.

  • 26.
    Tsai, H T
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Ballem, Mohamed
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Silica SBA-15 Template Assisted Synthesis of Ultrasmall and Homogeneously Sized Copper Nanoparticles2011In: JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, ISSN 1533-4880, Vol. 11, no 4, p. 3493-3498Article in journal (Refereed)
    Abstract [en]

    The synthesis of spherical copper nanoparticles with extremely narrow size distribution by electroless copper deposition on mesoporous silica support is described. The materials were characterized by nitrogen sorption, transmission electron microscopy, x-ray diffractometry and Fourier transform infrared spectroscopy. The copper nanoparticles have a cubic crystalline structure and an average particle size of 5.5 +/- 0.8 nm. The copper nanoparticles are stable, without detectable oxidation or further agglomeration under ambient conditions even after months. These results demonstrate that electroless copper reduction can be conducted and constrained within the mesoporous silica framework, which pave the way for engineered mesoreactors.

  • 27.
    Wu, Pei-Hsuan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Mäkie, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Ulm, Germany.
    Growth and Functionalization of Particle-Based Mesoporous Silica Films and Their Usage in Catalysis2019In: NANOMATERIALS, ISSN 2079-4991, Vol. 9, no 4, article id 562Article in journal (Refereed)
    Abstract [en]

    We report the formation of mesoporous films consisting of SBA-15 particles grown directly onto substrates and their usage as catalysts in esterification of acetic acid and ethanol. The film thickness was altered between 80 nm and 750 nm by adding NH4F to the synthesis solution. The salt also affects the formation rate of the particles, and substrates must be added during the formation of the siliceous network in the solution. Various substrate functionalizations were tested and hydrophobic substrates are required for a successful film growth. We show that large surfaces (amp;gt; 75 cm(2)), as well as 3D substrates, can be homogenously coated. Further, the films were functionalized, either with acetic acid through co-condensation, or by coating the films with a thin carbon layer through exposure to furfuryl alcohol fumes followed by carbonization and sulfonation with H2SO4. The carbon-coated film was shown to be an efficient catalyst in the esterification reaction with acetic acid and ethanol. Due to the short, accessible mesopores, chemical variability, and possibility to homogenously cover large, rough surfaces. the films have a large potential for usage in various applications such as catalysis, sensing, and drug delivery.

1 - 27 of 27
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