|
|
Quantum mechanical calculations of the properties of oligosilanes
Toman, Petr
Quantum mechanical study of polarons in oligo[methyl(phenyl)silanes] (OMPSi) was performed. The conformations of the defect-free OMPSi and OMPSi containing positive and negative polaron were optimized by measns of B3LYP method. For comparison and evaluation of the substituent effects, the conformation of the unsubstituted oligosilane was also calculated. The conformations were described by means of Si-Si bond lengths and Si-Si-Si bond angles. The negative polaron conformation shows a significant chain stretching. On the other hand, the positive polaron conformation is shrunk. The explanation is based on the changes of the electron densities. There is also a strong influence of the substituents on the conformation of the negative polaron. The middle Si-Si bond is much shorter for the substitute oligomer and the bond angles are smaller. On the other hand, the influence of the substituents on the conformation of the positive polaron is small.
|
|
|
Proceedings
Lukáš, Jaromír
Summaries of 24 lectures presented at the fourth Joint Korean-Czech Symposium on Macromolecular Chemistry held in Prague in December 2002. The lectures concentrated not only on fundamental topics of macromolecular chemistry and physics but also on application of polymers in such areas as biomedicine, membrane separation, and photoelectronics.
|
|
|
Image processing in multiphase polymer systems
Holoubek, Jaroslav
Application of image analysis in the real and inverse space (in the Fourier space) are presented for some multiphase polymer systems. The analysis of the thresholded images of back scattered light from thick polymer material gives information about size and concentration of minor phase domains. Similarly, the phase separation and dissolution processes can be characterized by processing of light scattered patterns detected during time evolution.
|
|
|
Study of supermolecular structure of polymers by light scattering methods
Holoubek, Jaroslav
Various optical techniques, especially light scattering methods, have been investigated as potential candidates for characterization of multiphase polymeric materials, i.e. to measure the size, shape and volume fraction of the minor phase and time evolution of morphology. Some supplementary information has been also obtained from model calculatios of dispersed-phase particles changes, time-resolved light scattering experiments and image analysis.
|
|
| |
|
| |
|
| |
|
| |
|
| |
|
|
Characterization of ionically active membranes
Kůdela, Vlastimil ; Richau, K. ; Schauer, Jan
It has been shown that liquid junction potentials (LJP) are the cause of a systematic error of hydroxonium ions (protons) static transport numbers in membranes made from sulfonated poly(phenylene oxide) if LJP are calculated from concentration potentials measured by means of KCl filled electrodes. The remedy has been found in the use of wire electrodes of second kind like Ag/AgCl. Theory and results.
|
guest ::
