Bottom-Up, Wet Chemical Technique for the Continuous Synthesis of Inorganic Nanoparticles

Continuous wet chemical approaches for the production of inorganic nanoparticles are important for large scale production of nanoparticles. Here we describe a bottom-up, wet chemical method applying a microjet reactor. This technique allows the separation between nucleation and growth in a continuous reactor environment. Zinc oxide (ZnO), magnetite (Fe3O4), as well as brushite (CaHPO4·2H2O), particles with a small particle size distribution can be obtained continuously by using the rapid mixing of two precursor solutions and the fast removal of the nuclei from the reaction environment. The final particles were characterized by FT-IR, TGA, DLS, XRD and SEM techniques. Systematic studies on the influence of the different process parameters, such as flow rate and process temperature, show that the particle size can be influenced. Zinc oxide was obtained with particle sizes between 44 nm and 102 nm. The obtained magnetite particles have particle sizes in the range of 46 nm to 132 nm. Brushite behaves differently; the obtained particles were shaped like small plates with edge lengths between 100 nm and 500 nm

Long Alkyl Chain Organophosphorus Coupling Agents for in Situ Surface Functionalization by Reactive Milling

Innovative synthetic approaches should be simple and environmentally friendly. Here, we present the surface modification of inorganic submicrometer particles with long alkyl chain organophosphorus coupling agents without the need of a solvent, which makes the technique environmentally friendly. In addition, it is of great benefit to realize two goals in one step: size reduction and, simultaneously, surface functionalization. A top-down approach for the synthesis of metal oxide particles with in situ surface functionalization is used to modify titania with long alkyl chain organophosphorus coupling agents. A high energy planetary ball mill was used to perform reactive milling using titania as inorganic pigment and long alkyl chain organophosphorus coupling agents like dodecyl and octadecyl phosphonic acid. The final products were characterized by IR, NMR and X-ray fluorescence spectroscopy, thermal and elemental analysis as well as by X-ray powder diffraction and scanning electron microscopy. The process entailed a tribochemical phase transformation from the starting material anatase to a high-pressure modification of titania and the thermodynamically more stable rutile depending on the process parameters. Furthermore, the particles show sizes between 100 nm and 300 nm and a degree of surface coverage up to 0.8 mmol phosphonate per gram

A comparison of synthetic strategies for the synthesis of metal oxide nanoparticles : reactive milling and microjet reactor process

This work investigates systematically synthetic strategies for inorganic nanoparticles. The main focus is the investigation of different process parameters (milling time/-speed or pressure/temperature) on the resulting particles. A top-down approach for the synthesis of inorganic metal oxide particles with in situ surface-modification is described, which is an application of reactive milling and can be performed in a high-energy planetary ball mill. Surface functionalized titania particles are obtained using various organophosphonic acids as surface-modifying agents. The process of particle size reduction and surface functionalization was accompanied by a tribochemical phase transformation from the starting material anatase to rutile and a high-pressure modification of titania. The obtained particles show sizes between 100 nm and 300 nm. A degree of surface coverage of up to 1.4 mmol/g particle could be reached. Furthermore, a wet chemical, bottom-up approach for the continuous production of inorganic nanoparticles was investigated for its suitability for the preparation of oxide nanoparticles. By means of a microjet reactor very short mixing times and the instant separation of already formed particles from the reaction zone can be achieved. As a result, uniform particles with a small size distribution can be obtained. Applying this method, zinc oxide and magnetite with particle sizes between 44 nm and 132 nm as well as flaky brushite were produced.Die vorliegende Arbeit untersucht systematisch Synthesemethoden für anorganische Nanopartikel. Im Mittelpunkt steht der Einfluss von Prozessparametern (Mahldauer/-geschwindigkeit bzw. Druck/Temperatur) auf die resultierenden Partikel. Es wird ein top-down Verfahren zur Synthese von Metalloxid-Partikeln mit in situ Oberflächenfunktionalisierung beschrieben. Es handelt sich um die Methode der Reaktivvermahlung, durchgeführt in einer Hochenergie-Planetenkugelmühle. Es konnte oberflächenmodifiziertes TiO2 erhalten werden. Als Funktionalisierungsreagenz wurden verschiedene Organophosphonsäuren eingesetzt. Neben der Partikelzerkleinerung und Funktionalisierung konnte eine tribochemische Phasenumwandlung des eingesetzten Anatas zu Rutil und hochdruck-TiO2 beobachtet werden. Die resultierenden Partikel zeigen Größen von 100 - 300 nm. Es konnte ein Funktionalisierungsgrad von bis zu 1,4 mmol/g Partikel erreicht werden. Des Weiteren wurde ein kontinuierliches, nasschemisches bottom-up Verfahren zur Synthese von anorganischen Nanopartikeln auf seine Eignung zur Herstellung oxidischer Nanopartikel systematisch untersucht. Mit Hilfe eines Microjet Reaktors ist es möglich, sehr kurze Mischzeiten und ein sofortiges Entfernen der bereits entstandenen Partikel aus der Reaktionszone zu erzielen, sodass gleichmäßig geformte Partikel mit einer schmalen Größenverteilung erhalten werden. Es wurden Zinkoxid und Magnetit mit Größen von 44 - 132 nm und plättchenförmiger Brushit hergestellt

Ein Vergleich von Synthesestrategien für die Synthese von Metalloxid Nanopartikeln : Reaktivvermahlung und Microjet Reaktor Prozess

This work investigates systematically synthetic strategies for inorganic nanoparticles. The main focus is the investigation of different process parameters (milling time/-speed or pressure/temperature) on the resulting particles. A top-down approach for the synthesis of inorganic metal oxide particles with in situ surface-modification is described, which is an application of reactive milling and can be performed in a high-energy planetary ball mill. Surface functionalized titania particles are obtained using various organophosphonic acids as surface-modifying agents. The process of particle size reduction and surface functionalization was accompanied by a tribochemical phase transformation from the starting material anatase to rutile and a high-pressure modification of titania. The obtained particles show sizes between 100 nm and 300 nm. A degree of surface coverage of up to 1.4 mmol/g particle could be reached. Furthermore, a wet chemical, bottom-up approach for the continuous production of inorganic nanoparticles was investigated for its suitability for the preparation of oxide nanoparticles. By means of a microjet reactor very short mixing times and the instant separation of already formed particles from the reaction zone can be achieved. As a result, uniform particles with a small size distribution can be obtained. Applying this method, zinc oxide and magnetite with particle sizes between 44 nm and 132 nm as well as flaky brushite were produced.Die vorliegende Arbeit untersucht systematisch Synthesemethoden für anorganische Nanopartikel. Im Mittelpunkt steht der Einfluss von Prozessparametern (Mahldauer/-geschwindigkeit bzw. Druck/Temperatur) auf die resultierenden Partikel. Es wird ein top-down Verfahren zur Synthese von Metalloxid-Partikeln mit in situ Oberflächenfunktionalisierung beschrieben. Es handelt sich um die Methode der Reaktivvermahlung, durchgeführt in einer Hochenergie-Planetenkugelmühle. Es konnte oberflächenmodifiziertes TiO2 erhalten werden. Als Funktionalisierungsreagenz wurden verschiedene Organophosphonsäuren eingesetzt. Neben der Partikelzerkleinerung und Funktionalisierung konnte eine tribochemische Phasenumwandlung des eingesetzten Anatas zu Rutil und hochdruck-TiO2 beobachtet werden. Die resultierenden Partikel zeigen Größen von 100 - 300 nm. Es konnte ein Funktionalisierungsgrad von bis zu 1,4 mmol/g Partikel erreicht werden. Des Weiteren wurde ein kontinuierliches, nasschemisches bottom-up Verfahren zur Synthese von anorganischen Nanopartikeln auf seine Eignung zur Herstellung oxidischer Nanopartikel systematisch untersucht. Mit Hilfe eines Microjet Reaktors ist es möglich, sehr kurze Mischzeiten und ein sofortiges Entfernen der bereits entstandenen Partikel aus der Reaktionszone zu erzielen, sodass gleichmäßig geformte Partikel mit einer schmalen Größenverteilung erhalten werden. Es wurden Zinkoxid und Magnetit mit Größen von 44 - 132 nm und plättchenförmiger Brushit hergestellt

Long Alkyl Chain Organophosphorus Coupling Agents for in Situ Surface Functionalization by Reactive Milling

Innovative synthetic approaches should be simple and environmentally friendly. Here, we present the surface modification of inorganic submicrometer particles with long alkyl chain organophosphorus coupling agents without the need of a solvent, which makes the technique environmentally friendly. In addition, it is of great benefit to realize two goals in one step: size reduction and, simultaneously, surface functionalization. A top-down approach for the synthesis of metal oxide particles with in situ surface functionalization is used to modify titania with long alkyl chain organophosphorus coupling agents. A high energy planetary ball mill was used to perform reactive milling using titania as inorganic pigment and long alkyl chain organophosphorus coupling agents like dodecyl and octadecyl phosphonic acid. The final products were characterized by IR, NMR and X-ray fluorescence spectroscopy, thermal and elemental analysis as well as by X-ray powder diffraction and scanning electron microscopy. The process entailed a tribochemical phase transformation from the starting material anatase to a high-pressure modification of titania and the thermodynamically more stable rutile depending on the process parameters. Furthermore, the particles show sizes between 100 nm and 300 nm and a degree of surface coverage up to 0.8 mmol phosphonate per gram

Bottom-Up, Wet Chemical Technique for the Continuous Synthesis of Inorganic Nanoparticles

Continuous wet chemical approaches for the production of inorganic nanoparticles are important for large scale production of nanoparticles. Here we describe a bottom-up, wet chemical method applying a microjet reactor. This technique allows the separation between nucleation and growth in a continuous reactor environment. Zinc oxide (ZnO), magnetite (Fe3O4), as well as brushite (CaHPO4·2H2O), particles with a small particle size distribution can be obtained continuously by using the rapid mixing of two precursor solutions and the fast removal of the nuclei from the reaction environment. The final particles were characterized by FT-IR, TGA, DLS, XRD and SEM techniques. Systematic studies on the influence of the different process parameters, such as flow rate and process temperature, show that the particle size can be influenced. Zinc oxide was obtained with particle sizes between 44 nm and 102 nm. The obtained magnetite particles have particle sizes in the range of 46 nm to 132 nm. Brushite behaves differently; the obtained particles were shaped like small plates with edge lengths between 100 nm and 500 nm