National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Preparation and study of a series of diketopyrrolopyrrole (DPP)-based polymers as photoactive substances
Solanský, Lukáš ; Richtár, Jan (referee) ; Cigánek, Martin (advisor)
The present diploma thesis deals with polymers based on organic pigments, their preparation, characterization and use as photoactive substances with a focus on artificial photosynthesis. The experimental part is devoted to the preparation of diketopyrrolopyrrole (DPP) based polymers. 7 DPP derivatives with 5 different side chains were prepared. The preparation of DPP polymers by Stille cross-coupling reaction and direct arylation were compared. Due to the higher efficiency and lower complexity of direct arylation, this polymerization method was used to prepare a series of 20 polymers consisting of a combination of 5 DPP derivatives and 4 comonomers. In the synthesis of several of the resulting polymers, the formation of an insoluble moiety was observed which could not be characterized by available methods, and even the subsequent application of such materials is not possible due to this. On the basis of the data obtained, it became apparent that in particular the bulky adamantane group and the comonomer tetrafluorobenzene were not suitable for the preparation of polymers, as they resulted in very limited soluble materials which, moreover, had a low degree of polymerization. In contrast, polymers containing butyl-TEG, octadecane, the comonomer thiophene and partially benzothiadiazole had degrees of polymerization in the range of 10-33 and exhibited excellent spectral and optoelectric properties. Tests of photocatalytic hydrogen evolution using DPP polymers are under development, but hydrogen was not demonstrably detected in initial measurements on selected polymer materials (P14 and P20).
Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Hromadová, Magdaléna ; Kocábová, Jana ; Kolivoška, Viliam ; Pospíšil, Lubomír
Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results show that the oxide growth kinetics depends on pH of the electrolyte\nsolution and the total amount of irreversibly formed oxide under the potentiodynamic\nconditions decreases with decreasing buffer pH in accord with thermodynamic considerations.\nCathodic current corresponding to hydrogen evolution reaction diminishes in the presence of\nanodically modified electrode compared to bare zirconium.

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