4.7 Synthesis of Coated Particles 75
To coat, for example, oxide particles with a polymer first, the particles are
synthesized in the microwave plasma region. After the cut-off tube, the organic
precursor is added. To obtain a polymer, the corresponding monomer or easily
evaporating oligomer is added. The temperature in the system is selected in a
way that the condensation of these organic precursor molecules at the surface of
the nanoparticle is possible. To obtain the correct temperature and to avoid particle losses by thermophoresis, the condensation zone is heated by a tubular
furnace or another heating system. Provided the compounds are selected properly, under the influence of temperature und the UV radiation from the microwave plasma, the monomer at the surface of the nanoparticles starts to polymerize.
Additionally, in many cases, the organic compounds react with the oxide particle
forming one huge molecule consisting of the particle and the polymer coating.
This changes the properties of the particles and the polymer molecules dramatically. As these new giant molecules have, for example, new optical properties,
the interaction between oxide nanoparticles and PMMA at the surface is explained
in Chapter 9. As an example, Figure 4.37 displays an iron oxide particle coated
with PMMA.
The coated particle displayed in Figure 4.37 consists of a core of maghemite,
γ-Fe 2 O 3 , and a PMMA coating. In this example, the ceramic core has a diameter
of 6–7 nm; whereas the thickness of the coating is between 3 and 4 nm. The device,
as depicted in Figure 4.36, may be setup with more than one stage for coating.
This allows a first coating, for example, with a luminescent material and a second
polymer layer for protection [10]. This leads to multifunctional particles [22]; details
of this class of nanocomposites are explained in Chapters 2 and 9.
Figure 4.36 Experimental setup for the
synthesis of polymer coated ceramic
nanoparticles according to Vollath et al. [21].
The system consists of a microwave plasma
reactor, where the ceramic particles are
produced, and subsequently a reaction zone
in a tubular furnace, where the coating
occurs.
Waveguide
Coated
parƟcles
Microwave
plasma
ReacƟon tube
Carrier gas and
first precursor
Organic
precursor
CoaƟng and
polymerizaƟon
Tubular furnace
To coat, for example, oxide particles with a polymer first, the particles are
synthesized in the microwave plasma region. After the cut-off tube, the organic
precursor is added. To obtain a polymer, the corresponding monomer or easily
evaporating oligomer is added. The temperature in the system is selected in a
way that the condensation of these organic precursor molecules at the surface of
the nanoparticle is possible. To obtain the correct temperature and to avoid particle losses by thermophoresis, the condensation zone is heated by a tubular
furnace or another heating system. Provided the compounds are selected properly, under the influence of temperature und the UV radiation from the microwave plasma, the monomer at the surface of the nanoparticles starts to polymerize.
Additionally, in many cases, the organic compounds react with the oxide particle
forming one huge molecule consisting of the particle and the polymer coating.
This changes the properties of the particles and the polymer molecules dramatically. As these new giant molecules have, for example, new optical properties,
the interaction between oxide nanoparticles and PMMA at the surface is explained
in Chapter 9. As an example, Figure 4.37 displays an iron oxide particle coated
with PMMA.
The coated particle displayed in Figure 4.37 consists of a core of maghemite,
γ-Fe 2 O 3 , and a PMMA coating. In this example, the ceramic core has a diameter
of 6–7 nm; whereas the thickness of the coating is between 3 and 4 nm. The device,
as depicted in Figure 4.36, may be setup with more than one stage for coating.
This allows a first coating, for example, with a luminescent material and a second
polymer layer for protection [10]. This leads to multifunctional particles [22]; details
of this class of nanocomposites are explained in Chapters 2 and 9.
Figure 4.36 Experimental setup for the
synthesis of polymer coated ceramic
nanoparticles according to Vollath et al. [21].
The system consists of a microwave plasma
reactor, where the ceramic particles are
produced, and subsequently a reaction zone
in a tubular furnace, where the coating
occurs.
Waveguide
Coated
parƟcles
Microwave
plasma
ReacƟon tube
Carrier gas and
first precursor
Organic
precursor
CoaƟng and
polymerizaƟon
Tubular furnace