About the Honorary Doctor

Jan Dhont is Professor at the Heinrich-Heine-Universität Düsseldorf and Director of the Institute of Biomacromolecular Systems and Processes at Forschungszentrum Jülich in Germany.

He is a prominent name within soft matter research and colloid chemistry, a part of physical chemistry bordering physics, biology and technology. His research focuses on statistical mechanics and transport properties in complex colloidal systems.

Jan Dhont has had strong ties with Lund University since 2013. Among other things, he has been involved in the Lund-led “Aniforce” research project and spends at least one month per year at the Division of Physical Chemistry, where he has become a much-appreciated research colleague and inspiring lecturer for doctoral students, who value his curiosity, openness and teaching skills.

“It is an honour to be named as an honorary doctor and to now have an official connection with Lund University,” says Jan Dhont.

Read more about the Honorary Doctor Jan Dhont on the Faculty of Science website

Abstract

Seminar title: ”Electric-field Induced Phases and Dynamical States in Suspensions of Rod-like Colloids”.

After a short introduction to colloids and liquid crystals, I will discuss the response of concentrated suspensions of highly charged, very long and thin, rod-like colloids to external electric fields. Fd-virus particles are used as a model system for such rod-like colloids. These virus particles consist of a dsDNA strand of a length of 880 nm, which is covered by 2700 coat protein, leading a core thickness of 7 nm. The coat proteins give rise a very large surface charge density of the fd-virus particles, which results it a large number of condensed ions close to the surface of the particles. Depending on the amplitude and frequency of the external field, transitions from a nematic to chiral nematic, and from a chiral nematic to a homeotropic phase are found. In addition, a field-induced dynamical state can be induced, where nematic domains persistently melt and reform. The time scale on which melting and reforming of nematic domains occurs, and the size of the domains, both diverge at what could be identified as a “non-equilibrium critical point”. An explanation of these phenomena is presented, both on an intuitive level and based on appropriate equations of motion for the orientational order parameter, where the field-induced dissociation/associated of condensed ions plays an important role.