(637f) A Novel Intensified Device for the Production of Highly Monodisperse Polymer Particles In the Low Nanometer Range Through Miniemulsion Polymerization

A novel
intensified device for the production of highly monodisperse polymer particles
in the low nanometer range through miniemulsion polymerization

Souilem Inès(1)*, Muller René(1), Holl Yves(2),
Bouquey Michel(1), Serra Christophe A(1)

* souilem@unistra.fr

1 Group for the Intensification and Intrapolation of
Polymer Processes (G2IP)

Laboratory of Polymer Engineering for High
Technologies (LIPHT), Eac(CNRS) 4379

 2 Group of Colloïdes et Macromolecules  / Charles
Sadron Institut

European Engineering School of Chemistry,
Polymer and Material Science (ECPM)

University of Strasbourg (UdS)

Abstract An
original device called RMX was used to synthesize miniemulsions of poly(methyl
methacrylate). This mixer/reactor is based on a strong elongational flow component
contributing to a highly efficient dispersive mixing compared to existing
laboratory mixers. It presents the following important technical features:

·        
mixing volumes in the range of 5 to 45 cc.

·        
easy feeding of components even for reactive
systems.

·        
tightness of liquids and gases is maintained
during all steps, authorizing the processing of materials containing volatile
components.

The
principle of operation is based on the alternative displacement of two opposite
pistons placed themselves in two different cylindrical chambers. Each piston
pushes the material from one chamber to the other through a static mixing
element, fitted with a given number of holes of diameter in the range 0.2 -1 mm (Figure 1).

Figure 1: Schematic
representation of the RMX device: P pistons ; C mixing chambers ; ME
mixing element

The first part of this work consists on testing the
efficiency of this device as a mixer. That's
why we worked on a direct emulsion (monomer in water) stabilized with a surfactant.
Figure 2 shows the evolution
of the droplet size of monomer during the dispersion step at different
operating pressures compared to the ultrasonification and ultraturrax. The
results show that only the RMX allows to reach very small droplet size (lower
than 80 nm) even with very low pressure.

Figure 2: Evolution
of the droplet size of monomer in the emulsification step: comparison between
ultrasonification, ultraturrax and RMX

The second part consists on synthesizing miniemulsions
of poly(methyl methacrylate). After the dispersion of all reagents, the
polymerization of the monomer takes place by increasing the temperature.

Upon polymerization, it was found that polymer
particles with diameters below 100 nm could be obtained, thus differing from
conventional dispersion methods that have not yet reached this size domain. The
influence of both material parameters (monomer, surfactant and inhibitor
concentrations) and process parameters (pressure and flow rate, number and size
of the holes) on the particle size distribution was also investigated.

For example, Figure 3 shows the evolution of particle
size and the particle size distribution (PSD) at different pressures.

Figure 3:
Evolution of the polymer particle size and the PSD as a function of the
pressure

Keywords: miniemulsion, static mixer/reactor, particle size, dispersion,
polymerization