Studie molekulárně hmotnostní a konfigurační stability substituovaných polyacetylenů

3 ABSTRACT Complexes [Rh(cycloolefin)(acac)] (cycloolefin = norborna-2,5-diene, cycloocta- 1,5-diene and cyclooctatetraene) were investigated as catalysts of polymerization of monosubstituted acetylenes into stereoregular cis-transoid polyacetylenes. All complexes were highly active in arylacetylenes polymerizations in both coordinating and non-coordinating solvents. Selection of solvent and cycloolefin ligand of the catalyst allowed the control over polymer MW. The onset of initiation in the [Rh(cycloolefin)(acac)]/monomer systems proceeded as the proton transfer from the monomer molecule to the acac ligand under the release of acetylacetone and coordination of -C≡CR ligand to Rh(cycloolefin) moiety. Cis-transoid poly(phenylacetylene) and poly[(2,4-difluorophenyl)acetylene]s with required initial MW were prepared with these catalysts and submitted to the long-term ageing in which the polymers were exposed to the atmosphere and diffuse daylight either dissolved in tetrahydrofuran or in the solid state. Tightly connected processes of cis-to-trans isomerization of the polymer main-chains double bonds and oxidative degradation were found to proceed during polymers ageing in the solution. Besides, the formation of corresponding cyclotrimers accompanied the polymers ageing. However, the cyclotrimers amount was...2 ABSTRAKT Byla studována katalytická aktivita komplexů [Rh(cykloolefin)(acac)] (cykloolefin = norborna-2,5-dien, cyklookta-1,5-dien a cyclooktatetraen) při polymerizaci monosubstituovaných acetylenů cílená na přípravu stereoregulárních cis-transoid polyacetylenů. Při polymerizacích arylacetylenů provedených v rozpouštědlech s různou koordinační schopností vykazovaly všechny studované komplexy vysokou aktivitu. Volbou rozpouštědla a cykloolefinového ligandu katalyzátoru bylo možné ovlivňovat molekulovou hmotnost polymerů. Počáteční fáze iniciace probíhala jako přenos protonu z koordinované molekuly monomeru na acac ligand za uvolňování acetylacetonu a koordinace -C≡CR ligandu k částici Rh(cycloolefin). S použitím těchto katalyzátorů byly připraveny cis-transoid poly(fenylacetylen) a poly[(2,4-difluorfenyl)acetylen]y s požadovanou molekulovou hmotností. Tyto polymery byly studovány s ohledem na stabilitu při dlouhodobém stárnutí v roztoku nebo v pevné fázi, při kterém byly vystaveny působení atmosféry a rozptýleného denního světla. Během stárnutí polymerů v roztoku docházelo ke dvěma propojeným dějům, a to k cis-trans izomerizaci dvojných vazeb na hlavním polymerním řetězci a k oxidativní degradaci. Stárnutí polymerů bylo doprovázeno též tvorbou příslušných cyklotrimerů. Množství vznikajících cyklotrimerů...Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Studa of Molecular Weight and Configurational Stability of Substituted Polyacetylenes

Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Study of molecular weight and configurational stability of substituted polyacetylenes

3 ABSTRACT Complexes [Rh(cycloolefin)(acac)] (cycloolefin = norborna-2,5-diene, cycloocta- 1,5-diene and cyclooctatetraene) were investigated as catalysts of polymerization of monosubstituted acetylenes into stereoregular cis-transoid polyacetylenes. All complexes were highly active in arylacetylenes polymerizations in both coordinating and non-coordinating solvents. Selection of solvent and cycloolefin ligand of the catalyst allowed the control over polymer MW. The onset of initiation in the [Rh(cycloolefin)(acac)]/monomer systems proceeded as the proton transfer from the monomer molecule to the acac ligand under the release of acetylacetone and coordination of -C≡CR ligand to Rh(cycloolefin) moiety. Cis-transoid poly(phenylacetylene) and poly[(2,4-difluorophenyl)acetylene]s with required initial MW were prepared with these catalysts and submitted to the long-term ageing in which the polymers were exposed to the atmosphere and diffuse daylight either dissolved in tetrahydrofuran or in the solid state. Tightly connected processes of cis-to-trans isomerization of the polymer main-chains double bonds and oxidative degradation were found to proceed during polymers ageing in the solution. Besides, the formation of corresponding cyclotrimers accompanied the polymers ageing. However, the cyclotrimers amount was..

Studie molekulárně hmotnostní a konfigurační stability substituovaných polyacetylenů

Complexes [Rh(cycloolefin)(acac)] (cycloolefin = norborna-2,5-diene, cycloocta- 1,5-diene and cyclooctatetraene) were investigated as catalysts of polymerization of monosubstituted acetylenes into stereoregular cis-transoid polyacetylenes. All complexes were highly active in arylacetylenes polymerizations in both coordinating and non-coordinating solvents. Selection of solvent and cycloolefin ligand of the catalyst allowed the control over polymer MW. The onset of initiation in the [Rh(cycloolefin)(acac)]/monomer systems proceeded as the proton transfer from the monomer molecule to the acac ligand under the release of acetylacetone and coordination of -C≡CR ligand to Rh(cycloolefin) moiety. Cis-transoid poly(phenylacetylene) and poly[(2,4-difluorophenyl)acetylene]s with required initial MW were prepared with these catalysts and submitted to the long-term ageing in which the polymers were exposed to the atmosphere and diffuse daylight either dissolved in tetrahydrofuran or in the solid state. Tightly connected processes of cis-to-trans isomerization of the polymer main-chains double bonds and oxidative degradation were found to proceed during polymers ageing in the solution. Besides, the formation of corresponding cyclotrimers accompanied the polymers ageing. However, the cyclotrimers amount was too...Byla studována katalytická aktivita komplexů [Rh(cykloolefin)(acac)] (cykloolefin = norborna-2,5-dien, cyklookta-1,5-dien a cyclooktatetraen) při polymerizaci monosubstituovaných acetylenů cílená na přípravu stereoregulárních cis-transoid polyacetylenů. Při polymerizacích arylacetylenů provedených v rozpouštědlech s různou koordinační schopností vykazovaly všechny studované komplexy vysokou aktivitu. Volbou rozpouštědla a cykloolefinového ligandu katalyzátoru bylo možné ovlivňovat molekulovou hmotnost polymerů. Počáteční fáze iniciace probíhala jako přenos protonu z koordinované molekuly monomeru na acac ligand za uvolňování acetylacetonu a koordinace -C≡CR ligandu k částici Rh(cycloolefin). S použitím těchto katalyzátorů byly připraveny cis-transoid poly(fenylacetylen) a poly[(2,4-difluorfenyl)acetylen]y s požadovanou molekulovou hmotností. Tyto polymery byly studovány s ohledem na stabilitu při dlouhodobém stárnutí v roztoku nebo v pevné fázi, při kterém byly vystaveny působení atmosféry a rozptýleného denního světla. Během stárnutí polymerů v roztoku docházelo ke dvěma propojeným dějům, a to k cis-trans izomerizaci dvojných vazeb na hlavním polymerním řetězci a k oxidativní degradaci. Stárnutí polymerů bylo doprovázeno též tvorbou příslušných cyklotrimerů. Množství vznikajících cyklotrimerů bylo...Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Studa of Molecular Weight and Configurational Stability of Substituted Polyacetylenes

Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Study of molecular weight and configurational stability of substituted polyacetylenes

Complexes [Rh(cycloolefin)(acac)] (cycloolefin = norborna-2,5-diene, cycloocta- 1,5-diene and cyclooctatetraene) were investigated as catalysts of polymerization of monosubstituted acetylenes into stereoregular cis-transoid polyacetylenes. All complexes were highly active in arylacetylenes polymerizations in both coordinating and non-coordinating solvents. Selection of solvent and cycloolefin ligand of the catalyst allowed the control over polymer MW. The onset of initiation in the [Rh(cycloolefin)(acac)]/monomer systems proceeded as the proton transfer from the monomer molecule to the acac ligand under the release of acetylacetone and coordination of -C≡CR ligand to Rh(cycloolefin) moiety. Cis-transoid poly(phenylacetylene) and poly[(2,4-difluorophenyl)acetylene]s with required initial MW were prepared with these catalysts and submitted to the long-term ageing in which the polymers were exposed to the atmosphere and diffuse daylight either dissolved in tetrahydrofuran or in the solid state. Tightly connected processes of cis-to-trans isomerization of the polymer main-chains double bonds and oxidative degradation were found to proceed during polymers ageing in the solution. Besides, the formation of corresponding cyclotrimers accompanied the polymers ageing. However, the cyclotrimers amount was too..

Study of molecular weight and configurational stability of substituted polyacetylenes

Complexes [Rh(cycloolefin)(acac)] (cycloolefin = norborna-2,5-diene, cycloocta- 1,5-diene and cyclooctatetraene) were investigated as catalysts of polymerization of monosubstituted acetylenes into stereoregular cis-transoid polyacetylenes. All complexes were highly active in arylacetylenes polymerizations in both coordinating and non-coordinating solvents. Selection of solvent and cycloolefin ligand of the catalyst allowed the control over polymer MW. The onset of initiation in the [Rh(cycloolefin)(acac)]/monomer systems proceeded as the proton transfer from the monomer molecule to the acac ligand under the release of acetylacetone and coordination of -C≡CR ligand to Rh(cycloolefin) moiety. Cis-transoid poly(phenylacetylene) and poly[(2,4-difluorophenyl)acetylene]s with required initial MW were prepared with these catalysts and submitted to the long-term ageing in which the polymers were exposed to the atmosphere and diffuse daylight either dissolved in tetrahydrofuran or in the solid state. Tightly connected processes of cis-to-trans isomerization of the polymer main-chains double bonds and oxidative degradation were found to proceed during polymers ageing in the solution. Besides, the formation of corresponding cyclotrimers accompanied the polymers ageing. However, the cyclotrimers amount was too..

Stability of MEH-PPV: Poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene]vinylene} in solutions exposed to air in the dark and at daylight at laboratory temperature

The long-term stability of poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene]vinylene} (MEH-PPV) in solutions exposed to air at daylight and in the dark at room temperature has been studied using the size exclusion chromatography (SEC), UV/vis, fluorescence and IR spectra of aged samples, and comparison of UV/vis spectra of SEC fractions. Solvents currently used in the preparation, analysis and processing of MEH-PPV were used: tetrahydrofuran (THF), chloroform (CHCl3) and chlorobenzene (PhCl). The SEC-DAD data revealed a serious decrease in the delocalization of electrons in MEH-PPV chains, even in the large ones, which proves a deep damage to the structure of the chains prior to their cleavage. The IR spectra of aged samples show that the saturation of main-chain double bonds and the changes in the substitution of phenylene rings are the main chemical structure defects present in chains of aged MEH-PPV. The rate as well as the extent of the overall degradation process is ca ten to fifty times enhanced by the ordinary daylight. The rate of cleavage and the damage to the structure of MEH-PPV molecules are significantly influenced by the choice of the solvent; they increase in the order: PhCl < CHCl3< THF. PhCl can be recommended as one of the best solvents for MEH-PPV processing from solutions