Department of Synthesis and Characterization of Polymers
The aim of the department is to cover completely the expertise in synthesis of polymers using various polymerization techniques including free radical, reversible-deactivation radical and anionic polymerizations. The second object of synthesis represents preparation, spectral characterization and mainly utilization of different fluorescence probes for characterization of polymer microstructure and for polymerization study mechanism. Modification of polymers by grafting, crosslinking and functionalizations and preparation of polymeric and inorganic nanoparticles and hybrids represents another part of synthetic direction. Prepared as well as comercial polymers are characterised by spectral methods (UV-VIS, FTIR, Fluorescence and Raman spectroscopy), thermal analysis (DSC, TGA, chemiluminescence, thermal and photo stability, flammability) and their molar characteristics by advanced HPLC techniques. Electron spin resonance (ESR) and positron annihilation lifetime spectroscopy (PALS) techniques are used for the microscopic structural-dynamic characterization of various pure and composed organic materials.
1. Study and development of reversible-deactivation radical polymerizations and synthesis of functional polymers
2. Inorganic and carbon (nano)particles and hybrids
3. Polymeric (nano)particles, (hydro)gels and (nano)fibres
4. Synthesis and properties of photoactive compounds
5. Synthesis of polymers and polymeric materials from renewable monomers
6. Degradation, stabilization and flammability of polymers
7. Liquid chromatography research for effective separation of macromolecules
8. Structure and physico - chemical properties of polymers
8. Structure and physico - chemical properties of polymers
Head of the Group: Josef Bartoš, D.Sc.
The Profile of the Group:
The research activities of the Group of Structure and physico-chemical properties are focused on a basic research of the mutual relationships between the chemical structure of constituents, their physical structure and numerous physical and physico-chemical properties of various organic materials in various phase and physical states, especially of polymers, using a unique combination of the external probe techniques using electron spin resonance (ESR) and positron annihilation lifetime spectroscopy (PALS); the latter in close collaboration with the Institute of Physics of SAS, Bratislava, Slovakia and other PALS groups (Poland) and the internal probing ones such as differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS) in close co-operation with the top dielectric teams in Europe (Germany, Spain) as well as on continuously developed phenomenological and theoretical methodologies of the microscopic characterization of the small molecular, oligo- and poly-meric organics compounds.
Materials, techniques, methodologies:
Our systematic fundamental research is aimed on two basic groups of organic materials: 1) pure organic compounds such as small molecular and oligo- and polymer media and 2) the so-called organic–inorganic nanosystems such as organic media confined in inorganic matrices (confiners) and organic media in nanocomposites with inorganic compounds (fillers). Various organic compounds of different types of the chemical structure such as non-polar vdW-bonded media and polar non-H-bonded (aprotic) and H-bonded (protic) ones are investigated by means of two special external microscopic probes: molecular-sized spin probes via ESR and atomic-sized ortho-positronium via PALS. Molecular mobility of one of the smallest quasi-spherical spin probe, namely, 2,2,6,6-tetra-methyl-piperidinyl-1-oxy (TEMPO), reflects the local microstructural and microdynamical surroundings of the investigated organic medium being measured through the spectral parameter of mobility, 2Azz‘, and the reorientation correlation time, τc, over a wide investigated temperature range from 100 K up to 360 K. The microscopic changes in the spin probe dynamics at the characteristic ESR and/or PALS temperatures are related to and interpreted by means of the changes in the specific heat and the electric dipole reorientation as obtained by DSC or BDS, respectively.
The representative results:
The first type of the problems consists in a unique combination of ESR and PALS studies on various pure organic materials> in the bulk state. Fig.1 displays the ESR response of the spin system 1,4-poly(isoprene)/TEMPO in a form of the temperature dependence of the spectral parameter of mobility which exhibits several distinct regions of spin probe mobility defining a set of the characteristic ESR temperatures such as TXislow, T50G and TXifast.
Fig.2 shows the more detailed ESR response of the spin probe TEMPO in oligomeric 1,4-poly (isoprene) in terms of the correlation time as a function of temperature which demonstrates the co-existence of slow and fast moving spin probe molecules over a certain temperature range, i.e., the occurence of the dynamic heterogeneity phenomenon even in one-component amorphous organic medium.This effect is of great importance in the field of glassy and polymer physics for understanding the evolution of molecular motion in glass-forming compounds on going from the normal liquid state through supercooled liquid state to the glassy state und the closely related glassification phenomenon as the basic feature of amorphous substances.
Annihilation of ortho-positronium (o-Ps) probe expressed by the temperature dependence of the o-Ps lifetime, τ3, mirrors the local free volume microstructure and its change due to the local dynamics of constituents in non-conducting materials such as organic media or/and inorganic matrices. Typical PALS response exhibits a few regions described by the characteristic PALS temperatures: Tb1G, Tb2G, TgPALS and Tb1L, Tb2L as demonstrated on the case of the 1,4-PIP sample - Fig.3. In some cases close coincindencies between the characteristic ESR and PALS temperatures can be found which indicate the common origin of both the related changes in the spin probe TEMPO rotation mobility and the o-Ps annihilation.
The mutual relationships between these ESR and PALS crossover effecs and, in some cases, the common origins of their coincidencies are currently revealed by using an appropriate combination of internal probe techniques such as DSC and/or BDS. Thus, in our representative case of 1,4-PIP Fig. 4 shows that the coincidence between the slow to fast motion regime transition of molecular probe at T50G and the change in the free volume expansion in liquid state at Tb1L are related to the onset of the local segmental α- relaxation process in the medium. On the other hand, the coincidence between an acceleration in the mobility within the fast regime at TXifast and the quasi-saturation effect in o-Ps lifetime at Tb2L are found to be close to the maximum of the primary (α-) relaxation, i.e., local segmental process as well as to the onset of the secondary normal (n-) relaxation, i.e., global chain process.
The second type of the problems solved in our research group consists in search for utilization of the afore-mentioned external probes in the microscopic characterization of various nanostructured systems and in development of the corresponding characterization methodologies. As an example, one group of them includes various organic media such as small molecular and oligomeric compounds confined in a variety of inorganic matrices (confiners). Fig.5 demonstrates the ESR responses of the spin probe TEMPO in a typical non-polar medium n-hexadecane (n-HXD) in comparison with a typical polar protic one, i.e. n-propanol (n-PrOH) in both the bulk states and the confined states in the inorganic matrix of silicagel (SG). The observed dramatic differences reflect the delicate mutual interactions between all the three components of the studied systems and suggest the potential of the molecular spin probing method in the detailed structural-dynamic characterization of the various confined organic media.
- BARTOŠ, Josef - ŠVAJDLENKOVÁ, Helena - ŠAUŠA, Ondrej - LUKEŠOVÁ, Miroslava - EHLERS, D. - MICHL, M. - LUNKENHEIMER, P. - LOIDL, A. Molecular probe dynamics and free volume in organic glass-formers and their relationships to structural relaxation: 1-propanol. In Journal of Physics- Condensed Matter, 2016, vol. 28, no. 1, 015101.
- ŠVAJDLENKOVÁ, Helena - ZGARDZINSKA, B. - LUKEŠOVÁ, Miroslava - BARTOŠ, Josef. Spin probe dynamics in relation to free volume in crystalline organics from ESR and PALS: Cyclohexane. In Chemical Physics Letters, 2016, vol. 643, p. 98-102.
- LUKEŠOVÁ, Miroslava - ZGARDZINSKA, B. - ŠVAJDLENKOVÁ, Helena - ZALESKI, R. - CHARMAS, B. - BARTOŠ, Josef. Spin probe dynamics in relation to free volume in crystalline organics from ESR and PALS: N-tridecane. In Physica B: Condensed Matter, 2015, vol. 476, p. 100-108.
- LUKEŠOVÁ, Miroslava - ŠVAJDLENKOVÁ, Helena - SIPPEL, Pit - MACOVÁ, Eva - BEREK, Dušan - LOIDL, Alois - BARTOŠ, Josef. Spin probe dynamics of n-hexadecane in confined geometry. In European Physical Journal B, 2015, vol. 88, art.no. 46.
- BARTOŠ, Josef - ŠVAJDLENKOVÁ, Helena - LUKEŠOVÁ, Miroslava - YU, Y. - KRAUSE-REHBERG, R. Molecular dynamics and free volume in organic glass-formers: A series of oligomer and polymer 1,4-poly(isoprene)s. In Chemical Physics Letters, 2014, vol. 602, p. 28-33.
- BARTOŠ, Josef - ŠVAJDLENKOVÁ, Helena - ZALESKI, R. - EDELMANN, M. - LUKEŠOVÁ, Miroslava. Spin probe dynamics in relation to free volume in crystalline organics by means of ESR and PALS: n-Hexadecane. In Physica B: Condensed Matter, 2013, vol. 430, p. 99 - 105.
- BARTOŠ, Josef - ŠVAJDLENKOVÁ, Helena - YU, Y. - DLUBEK, G. - KRAUSE-REHBERG, R. Molecular probe dynamics and free volume in glass-formers: 1,2- and 1,4-poly(butadiene)s. In Chemical Physics Letters, 2013, vol. 584, p. 88 - 92.
- YANG, Yu - DLUBEK, Gunter - BARTOŠ, Josef - ŠVAJDLENKOVÁ, Helena - KRAUSE-REHBERG, Reinhard. Relationships between positron lifetime and dynamics of polymers. In Materials Science Forum, 2013, vol. 733, p. 179 - 182.
- BARTOŠ, Josef - ISKROVÁ - MIKLOŠOVIČOVÁ, Martina - CANGIALOSI, D. - ALEGRÍA, A. - ŠAUŠA, Ondrej - ŠVAJDLENKOVÁ, Helena - ARBE, A. - KRIŠTIAK, Jozef - COLMENERO, J. Positron annihilation and relaxation dynamics from dielectric spectroscopy: Poly (vinylmethylether). In Journal of Physics: Condensed Matter, 2012, vol. 24, art.no.155104.
- ŠVAJDLENKOVÁ, Helena - ŠAUŠA, Ondrej - ISKROVÁ - MIKLOŠOVIČOVÁ, Martina - MAJERNÍK, V. - KRIŠTIAK, Jozef - BARTOŠ, Josef. On the relationships between guest molecular dynamics and free volume in a series of small molecular and polymer glass-formers. In Chemical Physics Letters, 2012, vol. 539 - 540, p. 39 - 44.
- BARTOŠ, Josef - ISKROVÁ, Martina - KOHLER, M. - WEHN, R. - ŠAUŠA, Ondrej - LUNKENHEIMER, P. - KRIŠTIAK, Jozef - LOIDL, A. Positron annihilation response and broadband dielectric spectroscopy: Salol. In European Physical Journal E : Soft Matter and Biological Physics, 2011, vol. 34, p. 104 - 114.
- BARTOŠ, Josef - ŠAUŠA, Ondrej - KOHLER, M. - ŠVAJDLENKOVÁ, Helena - LUNKENHEIMER, P. - KRIŠTIAK, Jozef - LOIDL, A. Positron annihilation and broadband dielectric spectroscopy : A series of propylene glycols. In Journal of Non-Crystalline Solids, 2011, vol. 357, p. 376 - 384.
- BARTOŠ, Josef - ŠAUŠA, Ondrej - SCHWARTZ, G.A. - ALEGRÍA, A. - ALBERDI, J.M. - ARBE, A. - KRIŠTIAK, Jozef - COLMENERO, J. Positron annihilation and relaxation dynamics from dielectric spectroscopy and nuclear magnetic resonance: cis-trans-1,4-poly(butadiene). In Journal of Chemical Physics, 2011, vol.134, art.no.164507 p.1-10.
- ŠVAJDLENKOVÁ, Helena - ISKROVÁ, Martina - ŠAUŠA, Ondrej - DLUBEK, G. - KRIŠTIAK, Jozef - BARTOŠ, Josef. The spin probe dynamics and the free volume in a series of amorphous polymer glass-formers. In Macromolecular Symposia, 2011, vol. 305, p. 108 - 115.