Emeritus

Education

• Ph.D., University of Ljubljana

Research Interests

Research in solution theories focuses on colloidal, biopolymeric and electrolyte systems relevant to biophysics and chemical engineering. We have been developing and applying analytic methods and computational techniques based on principles of statistical mechanics. These include molecular and mesoscopic simulations, integral equation theory of liquids, and field-theoretic approaches to soft matter and disordered materials. The goal is to explain microscopic mechanisms behind observed macroscopic behaviors, predict new designs, and identify conditions optimizing biological function or pragmatic performance of the material.

Our work is often synergistic with experimental groups in respective fields. Systems of interest include dispersions of nanoparticles, synthetic and biological polyelectrolytes, surfactant self-assemblies, liquid and quenched ionic media and aggregating protein solutions. This research has helped elucidate several crucial aspects of solution electrostatics and solvation phenomena that affect the structure and phase behavior of colloidal solutions, including the important role of ion-ion correlations in intercolloidal attraction.

In recent years, we have been concerned with modeling of interfacial liquids under the influence of confining surfaces, neutral and ionic co-solutes, and applied external field. These efforts advance our understanding of solvation forces, and the ability to tune materials’ surface thermodynamics for new applications.

Specific salt effects, crucial to solution properties of biomolecules, are analyzed by a combination of molecular simulations and integral equation approaches. We are extending these studies to solutions of nanoparticles with ionic ingredients. In view of close relation with physics of ionic colloids, our studies also impact several topics in colloidal theory, including hydration and confinement effects, ion-recognition, and multipolar electrostatic interactions.

Select Publications

D. Bratko, N. Mulpuri, Dynamic permittivity of confined water under a static background field, J. Chem. Phys. 161, 154705 (2024)

D. Bratko, Reversible surface energy storage in molecular-scale porous materials, Special Issue on Wettability Control Materials: Synthesis, Characterization, Properties and Applications, Molecules 29, 664 (2024)

N. Mulpuri, D. Bratko, Polarity-dependence of the nonlinear dielectric response in interfacial water, J. Chem. Phys. 158, 134716 (2023)

D. Vanzo, A. Luzar, D. Bratko, Pressure-sensitive conversions between Cassie and Wenzel states on a nanocorrugated surface, Theme Series on Materials by Design Under Pressure: Experiments and Theory, Appl. Phys. A 128, 323 (2022)

D. Vanzo, A. Luzar, D. Bratko, Reversible electrowetting transitions on superhydrophobic surfaces, Phys. Chem. Chem. Phys. 23, 27005 (2021)

S. G. Zamfir, F. Moucka, D. Bratko, High Pressure Infiltration/Expulsion of Aqueous NaCl in Planar Hydrophopic Nanopores, J. Phys. Chem. C 124, 23433 (2020)