Particles by polymerization process

At Fraunhofer IGB we produce customer-specific nano- and microparticles with cores of organic material from commercially available polymers or tailor-made polymer materials using different polymerization techniques such as miniemulsion or dispersion polymerization.

Method and particle size

Polymerisation techniques.
Polymerisation techniques and achievable particle sizes.

Achievable particle sizes range from a few nanometers to several 100 micrometers. An overview of the available methods is given in the scheme.

Molecular imprinting

en
Principle of molecular imprinting of polymer nanoparticles.
en
Molecular imprinting of polymer nanoparticles.

In molecular imprinting, copolymer particles are first produced by a so-called mini-emulsion polymerization in the presence of the "guest molecules" to be removed. The polymer particles cross-link around the guest or later target molecules. They act like molecular stamps (templates) which leave a spatial-physical as well as chemical imprint in the material. After complete polymerisation, the guest molecules are extracted and small nanoparticles are obtained, which can bind the target molecules to the specific receptor sites again. The molecularly imprinted nanopolymers are called NanoMIP (nanoscopic molecularly imprinted polymers).

Mini emulsion polymerization

At Fraunhofer IGB, molecularly imprinted polymer nanoparticles are represented by miniemulsion polymerization with typical particle sizes in the range of 50 to 300 nm. This process is a heterophase polymerization in which two immiscible liquid phases are homogeneously and stably emulsified under the influence of high shear forces, the use of surfactants and co-stabilizers. The resulting nanodroplets of monomer, template molecule and osmotic reagent form nanoreactors in which the polymerization takes place. The resulting polymer nanoparticles are direct images of the emulsion droplets in terms of size and morphology.

This technique of synthesizing molecularly imprinted polymer nanoparticles, which has been patented by Fraunhofer IGB, offers the advantage over other common methods of polymer nanoparticle synthesis such as emulsion polymerization or precipitation polymerization that the synthesis - although complex - is carried out in a single step with quantitative yield and independent of the diffusion of the educts.

In addition to classical miniemulsion polymerization, which is used for the molecular imprinting of hydrophobic molecules, the process can be carried out in an inverse miniemulsion polymerization. This technique can be used to produce nanoparticles for the molecular recognition of hydrophilic molecules such as peptides and proteins.

Process steps in classical (a) and inverse (b) mini-emulsion polymerisation.
Process steps in classical (a) and inverse (b) mini-emulsion polymerisation.
Emulsion polymerisation.
© BioRegio STERN / Photo: Eric A Lichtenscheidt
UV-initiated mini-emulsion polymerisation in an immersion lamp reactor. Polymerisation at nanoMIPs with Dr. Melanie Dettling.
Miniaturised and parallelised UV glass reactors to optimise nanoparticle production.
Miniaturised and parallelised UV glass reactors to optimise nanoparticle production.