Magnetically active anisotropic composite systems - MACOSYS

The project has targeted basic research on composite materials (ferronematics) consisting of liquid crystals and various magnetic nanoparticles (MNPs), with the key objectives: (i.) to determine optical and dielectric responses to low magnetic fields, (ii.) to explore the conditions influence these responses, (iii.) to contribute to the better understanding of the aggregation process, (iv.) to enhance the magnetic field induced phase transition temperature shift, and (v.) to produce a magnetically sensitive, optically anisotropic self-standing films. The project realisation has led to the following achievements:

• the optical and dielectric response of ferronematics to low magnetic fields have been measured with spherical and rod-like MNPs, as well as with carbon nanotubes;
• the role of the small bias magnetic field, and that of the anchoring conditions at the interfaces has been clarified;
• the influence of the aggregation of MNPs on the response to low magnetic fields, and on the magnetic susceptibility has been determined in various ferronematics – see figure;
• both positive and negative shifts of the phase transitions temperature have been achieved by the anisometry of MNPs, as well as by application of a magnetic field;
• novel photo-sensitive liquid crystal monomers and polymers have been synthetized and characterized.

The figure shows two ferronematics prepared in the identical procedure, with the same  spherical Fe₃O₄ nanoparticles (having a mean diameter of 20nm), in the same volume  concentration (10^-4), however, in different LC matrices: 6CHBT (on the left), and 6CB (on the right).

The project resulted in 18 peer-reviewed journal articles, with a cumulative I.F. above 40.

Project Details