RESEARCH
Research topics studied in our laboratory
i) high molecular substances classified as potential contaminants;
ii) organometallic compound serving as MOVPE precursors;
iii) biogenic substances (terpenes, fragrance, agents having hydrogen bonding, infochemicals).
We combine experimental and computational approaches:
a) experimental determination of vapor pressure in low-pressure area (below 1 kPa);
b) calorimetric determination of the heat capacity and thermal phase transitions in the temperature range from 2 to 600 K;
c) advanced ab initio calculations of the properties of substances in the state of ideal gas;
d) simultaneous correlation (SimCor) of vapor pressures (both literature and measured in our laboratory) and related thermal properties, which allows evaluation of the saturated vapor pressure and vaporization / sublimation enthalpy at extremely low pressures, where direct experimental determination is not possible.
e) sublimation enthalpy obtained by Simcor is used for verification of computational methodologies, leading to realistic ab initio calculations of the sublimation equlibria, developped in the group of Computational thermodynamics ut UCT Prague
B) Calorimetry is also used to study
i) new inorganic compounds used in
the production of semiconductors,
ii) polyaromatic hydrocarbons and
bitumens,
iii) pharmacologically important substances (aminoacids and their derivatives, APIs (Active Pharmacologic Ingredience), biocompatible polymeres used in pharmacology, ASD (Amorphous Solid Dispersions) prepared from API+polymer.
Grant projects:
19) Properties of alternative technical fluids based on hydrofluoroethers and their blends
(Czech Science Fundation GA_24-10191K, Principal investigator: Dr. V. Vinš (Institute of Thermomechnics, AS ). Co-investigator Dr. V. Štejfa, 2024-2027)
18) Development of procedures for the solidification of highly active waste generated during the liquidation of a severe accident of a Nuclear Power Plant and assessment of their disposal in a radioactive waste repository.
(Technological Agency of the Czech Republic, TK05020061, Principal investigator M. Straka (UJV Řež), Co-investigator: Prof. K. Růžička, 2023-2025)
17) Rational design of drug delivery systems based on tailored biodegradable polymers using an iterative in silico and experimental approach
(Czech Science Fundation GA_22-07164S, Principal investigator: Prof. M. Fulem, 2022-2024)
The objective is to explore the current possibilities of in silico approaches as tools for the rational design of drug delivery systems. The project consists of interconnected activities involving both experimental and theoretical undertakings, which will lead to the development of an optimized computational tool for the selection of polymeric carriers for given drugs. The performance-related characteristics of the resultant drug delivery systems will be optimized. The research methodology is based on performing an iterative procedure in the following areas:
i) synthesis and characterization of tunable biodegradable polymers,
ii) experimental drug-polymer compatibility screening,
iii) in silico drug-polymer compatibility prediction, and
iv) preparation and characterization of drug delivery systems in the form of amorphous solid dispersions and nanoparticles.
The theoretical approaches investigated involve quantum-mechanical (QM) models (COSMO-RS), advanced equations of state (PC-SAFT) with QM parametrization, and molecular dynamics and Monte Carlo simulations.
16) Stability of amorphous solid dispersions: Predictions by SAFT equations of state and their experimental verification
(Czech Science Fundation GA_19-02889S, principal investigator M.Fulem, 2019-2021)
In the proposed project, the performance of various SAFT-type molecular-based equations of state to predict the phase behavior of amorphous solid dispersions API + polymer will be explored by pursuing a co-operative theoretical and experimental research in the following main areas:
i) implementation and extensive testing of selected SAFT-type models including the development of parametrization methodology for APIs and polymers and the conduction of necessary experiments (e.g. measurements of API solubilities in various solvents and densities of polymer melts)
ii) extensive measurements of solubilities of API in polymer matrices using various DSC-based methods and their mutual comparisons
iii) determination of calorimetric API properties, such as heat capacities of condensed phases, required for rigorous calculations of solubilities
iv) preparation of ASD formulations with various API loadings by hot-melt extrusion, their storage at defined conditions, and testing of a long-term stability required to evaluate the predictive power of computational approaches.
15) Ab Initio Investigation of Polymorphism of Active Pharmaceutical Ingredients Supported by State of the Art NMR Crystallographic and Calorimetric Experiments
Grant type and funder: Ministry of Education, Youth and Sports, program INTER-EXCELLENCE, subprogram INTER-ACTION, project LTAUSA18
Co-investigator: Dr. Jiří Brus (Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic) American partner: Prof. Gregory O. J. Beran (University of California, Riverside)
Project Duration: 2019-2022.
Development of new medicaments always includes a costly and time-consuming stage of polymorph screening for proposed active pharmaceutical ingredients (API). Physico-chemical properties and stability of all relevant polymorphs need to be determined experimentally under a broad range of conditions to guarantee the safety and efficiency of the drug use. Our group provides highly-reliable and accurate experimental data on phase behavior (polymorph ranking, sublimation enthalpies and saturated vapor pressures), which serve as indispensable reference data for validation of new ab initio predictive methodologies, which are developped by the group of Computational thermodynamics at UCT and by the American partner (UCR). Calorimetric investigations (differential scanning, precise Tian-Calvet type, and relaxation calorimetry) and vapor pressure measurements using the static method are performed in our group at UCT over a broad range of temperatures to acquire reliable experimental data on enthalpies of phase transitions, their temperatures and sublimation pressures of the API. Such data fill the gaps in the available thermophysical data for given API and, furthermore, they will enable to critically assess the computational uncertainties related to the individual blocks of the developed methodology.
14) Theoretical and experimental study of thermodynamic properties and phase behavior of molecular crystals
(Czech Science Fundation GA_17-03875S, principal investigator M.Fulem, 2017-2019)
The goal of the project is to gain an insight into current possibilities of first-principles calculations to provide reliable thermodynamic data for molecular crystals and to predict their phase behavior . In the theoretical part, quantum chemical methods in connection with a quasi-harmonic treatment of thermal expansion of crystal lattice will be applied to obtain thermodynamic properties (sublimation enthalpies and pressures, heat capacities, etc.) as a function of temperature for selected biochemical model compounds, presenting various molecular moieties and a wide range of intermolecular interactions representing thus a general set for testing computational methodolgies. Extensive experimental studies of sublimation thermodynamic properties as well as calorimetric measurements including both phase behavior and heat capacity determinations in wide temperature ranges (2 K to decomposition temperature) will be performed with the aim to establish a reliable and thermodynamically consistent database required for the evaluation of uncertainties of computational methodologies.
13) The role of nonstoichimetry and nanosizing in material properties of metal oxides
(Czech Science Fundation GA_17-13161S, investigator Květoslav Růžička,
principal investigator D.Sedmidubský (Dept. Inorg. Chem) 2017-2019)
Oxide materials are currently widely
applied in a number of industries and hence they are in a
long-time focus of many fields of material research. Among their
properties the variable stoichiometry imposed by crystal defects
formation as well as surface energetics manifested by different behavior
brought about by particle nanosizing play a crucial role. The purpose
of this project is a complex analysis of oxygen nonstoichiometry
influence on the fundamental thermodynamic material properties (heat
capacity and thermal expansion) of properly selected metal oxides
(cobaltites, ferrates, cuprates) as well as the
assessment of nanosizing and nanostructuring on the thermodynamic
behavior of oxide phases. These phenomena, having an essential
importance for a controlled synthesis of materials with
desired properties, will be examined by a combined approach of
experimental synthesis and analytical techniques and theoretical
modeling methods.
Goals of the project:
1.Analysis of variable oxygen stoichiometry influence on the material
properties of metal oxides, standardization of calorimetry and
thermoanalytical data treatment.
2. Analysis of nanosizing effect on thermodynamic behaviour of metal oxides.
3. Theoretical modeling of the studied phenomena.
12) New 2D layered chalcogenides thin films and 3D nanostructures: Synthesis and characterization
(Czech Science Fundation GA_15-07912S, 2015-2017, principal investigator prof. T. Wagner, University of Pardubice)
Metal organic vapor phase epitaxy (MOVPE) is leading technology for preparation of semiconductor structures for electronic and optoelectronic devices. MOVPE successful application and future development depends on availability of suitable organometallic (OM) precursors of reasonable volatility. Many of the currently used precursors are toxic, pyrophoric or sensitive to moisture and oxygen. The goal of presented project is: 1) to develop new, technologically promising and safe precursors, 2) to evaluate their usability by measuring their vapor pressures and 3) to test precursors with favorable properties by growing of MOVPE epitaxial structures; 4) complex characterization of the prepared materials and comparison od the results with theoretical electronic structure calculations. This project will benefit from expertise of two institutions gained in areas of i) OM precursor preparation (Univ. Pardubice); ii) thermal analysis and vapor pressure measurements (ICT Prague); iii) film growth by MOVPE (ICT Prague) and by spin coating (Univ. Pardubice; iv) characterization of thin layers
11) Center for Analysis and Characterization of Advanced Materials
(Min. Education CR, project C16/2014 ,
2014, principal investigator K.Růžička, in cooperation with Prof. Dr.
Ing. David Sedmidubský, prof. Ing. Jindřich Leitner, DrSc., doc. Ing.
Martin Vrňata, Ph.D.)
10) Thin films of magnetically doped GaN
(Czech Science Fundation GA_13-20507S, principal investigator Prof. David Sedmidubský, 2013-2016)
Materials with both semiconductor and magnetic properties, which are commonly called dilute magnetic semiconductors (DMS), are currently considered as most applicable in the fabrication of spintronic devices - viable candidates for advanced computing and communication technologies.We aim to study the wide-gap GaN where, in order to produce a DMS with a high ferromagnetic Curie temperature, the transition metal (TM) and rare earths (RE) will be doped into thin layers of the host GaN structure. Simultaneously, TM and RE doped bulk GaN samples will be prepared as well. The samples will be characterized by means of spectroscopic methods and their structural, magnetic and magnetotransport properties will be measured. The observed characteristics will be critically analyzed and confronted with calculations of electronic structure and the origin of magnetism will be discussed regarding both the intrinsic mechanism of exchange interactions and the possible formation of other magnetic phases.
9) Thermodynamic Property Data of Terpenes and Terpenoids as Important Biogenic Volatile Organic Compounds in the Environment,
FCT Portugal, PTDC/AAC-AMB/121161/2010, 2012-2014 (Principal
investigator Dr. B. Schroeder, University of Aveiro, University of
Porto, Portugal)
8) Reliable vapor pressure measurements for electronics and optical coatings
(project KONTAKT ME10049, principal investigator M.Fulem, 2010-2012, with Dr. Robert Berg, NIST Gaithersburg, USA)
7) Development and application of methology for vapour pressure
determination by a combination of static and chromatographic techniques
(Czech Science Fundation GA ČR 203/09/1327, principal investigator K.Růžička, 2009-2011, with IOCB CAS, IRSM CAS)
Vapour pressure plays a critically important role in a number of applications ranging from technology to ecology. Thought there is a vast number of compounds with well established vapour pressures, measurements are still needed, especially in the low pressure region (below 1 kPa). Static method is a well established method for vapour pressure measurement. On the other hand, need of very pure and carefully degassed samples makes the method laborious, costly and slow. Methods based on determination of gas-chromatographic retention time are fast and require only a very small amount of the compound. In contrary to most other methods, sample purity is of little concern. Besides these promising features there are some limitations and disadvantages (e.g. activity coefficient problems, accurate data for reference compounds). Combination of the two techniques could solve most of the problems currently encountered, it was however found that the GC-RT method uses too many simplifications and assumptions and published results are in most cases dubious.
6) Measurement of vapour pressure of metal organic and related precursors suitable for use in nanostructure production
(Czech Science Fundation GA ČR 203/08/0217, principal investigator V.Růžička, 2008-2010. with Inst of Physics AS ČR)
5) Thermochemical properties of lead-free ferroelectric oxides
available for FeRAM fabrication
(Czech Science Fundation GA ČR
104/07/1209, principal investigator J.Leitner , 2007 - 2009)
The main aim of the proposed project is experimental determination, theoretical calculation and empirical estimation of the thermodynamic properties of mixed oxides in the system Bi2O3-SrO-Ta2O5-Nb2O5. Moreover various thermodynamic calculations will be performed which results will be employed for the thermodynamic simulation of thin layers deposition of Bi2SrTa2O9 and Bi2SrNb2O9 by the MOCVD method. Powder samples of investigated oxides will be prepared by the standard ceramic procedure, their phase composition will be determined by XRD and their stoichiometry will be analyzed by XRF spectroscopy, EMPA and/or AAS. The heat capacity and the heat content of the prepared samples will be measured by various calorimetric techniques. The computer code Wien2k based on the linearized augmented plane waves method (LAPW) will be employed for the ab-initio calculations.
4) Precise measurement of vapor pressure of organometallic compounds
( Czech Science Fundation GA ČR 203/04/0484, principal investigator V.Růžička, 2004-2006, with Inst of Physics AS ČR)
3) Termodynamic study of organic compounds and their solutions in water at extreme conditions
( Czech Science Fundation GA ČR 203/96/1162, principal investigator V.Růžička, 1996-1998, with ICPF AS ČR)
2) Experimental stude of physico-chemical properties for compounds of environmental and industrial importance
(Czech Science Fundation GA ČR 203/93/0973, principal investigator V.Růžička, 1993-1995, with ICPF AS ČR)
( TEMPUS JEP-4240-92, 1992-1995. principal investigator V.Růžička. Joint project with Universite Blaise Pascal, Clermont-Ferrand, France (coordinator) and Ruprecht-Karls-Universitet Heidelberg, Germany)