Metyloalumoksany jako komponenty hybrydowych kompozytów polimerowych

Maciej Marczewski

Abstract

The aim of the presented work was the use of methylalumoxanes as components of hybrid organic-inorganic materials. The work can be divided into three main parts. The first part correspond to the research on the possibility of functionalization of methylalumoxane molecule by compounds containing hydroxyl group (alcohols, polyethylene glycols). In this part several reactions between methylalumoxane and various alcohols (methanol, ethanol, isopropanol, n-butanol) and polyethylene glycol at various molar ratios were investigated. Obtained results show that methylalumoxane can be used as a precursor of hybrid systems. The second part of presented work is devoted to the urea–urethane elastomers which were synthesized in a polyaddition reaction of ethylene oligoadipate (OAE) (an average molecular weight 2000) with bis(4-isocyanatephenyl)methane (MDI). Dicyandiamide was used as a chain extender. In order to obtain hybrid nanocomposites, OAE was modified by the reaction with methylalumoxanes (MAO) prior to use. The excess of active methyl groups of MAO was deactivated by reactions with alcohols or alkylphosphates. This method allowed to introduce nanosized aluminum-oxide based moieties into the polyurethane. The content of nanoparticles was equal to 3 wt. %. The aim of this part of my PhD thesis was to synthesize a homogeneous molecular dispersion of aluminum-oxide units in order to obtain urea–urethane nanocomposites with a higher fire resistance and improved mechanical properties. Microstructure of the nanocomposites was studied using high resolution scanning electron microscopy (HRSEM). Mechanical properties were examined by standard testing procedures. Flammability tests were also performed using a cone calorimeter under heat flux equal to 50 kW/m2. The results of the microstructure studies show even distribution of the nano-sized aluminum-oxide units in the polyurethane bulk. An increase of such properties as Young’s modulus and hardness, accompanied by a significant decrease in the heat release rate was observed. The third part of the presented work corresponds to the synthesis of hybrid composite polymer electrolytes. The systems studied based on the MAO organometallic precursor can be divided into three main groups. In the first one, the product of the reaction of monocapped oligoether (of various Mw being in range 350 to 1000 g/mol) with MAO was used as the only constituent of the polymeric matrix. In this case the samples were characterized not only by changing molecular weight of the organic compound but also by the varying amount of Al-CH3 moieties undergoing the reaction with the –OH groups. In the second case the reaction was carried out in two steps. The second group of electrolytes was obtained in a reaction of a branched system with PEG molecules containing two –OH moieties – in this situation PEG acted as a crosslinking agent. Contrary to the first case where a viscous liquid was formed, in the later case the consistency of the sample varies from liquid through rubbery to brittle solid depending on the Mw of the organic compounds and the sample composition. In the third case a polymer blend was obtained by mixing PEGDME (Mw = 500 g/mol) with the product of a reaction of MAO with PEGME (Mw = 350 g/mol). In this case the first oligoether compound did not contain in its structure any free –OH moieties and, in consequence, did not take part in chemical interactions with the MAO molecule. In all the cases two lithium salts (LiClO4 and LICF3SO3) were added to the system. On the basis of obtained results I can report the formation of a new type of hybrid organic-inorganic composite polymeric electrolyte. The novelty is based on the fact that the organometallic precursor used formed a nanosized Al-O cage itself. Thus, in consequence, a system was created being intermediate between typical nanocomposites with mechanically dispersed filler grains and materials obtained previously by the sol-gel type of reaction. This system was characterized by electrical, thermal and mechanical properties which can be easily tailored by an appropriate choice of branching and cross-linking oligoglycols, molecular weight and molar ratio between nanocores and both reactants. FTIR experiments reveal slightly improved salt dissociation in the electrolyte containing MAO whose properties can be correlated with improved cationic transference numbers measured for electrolytes containing LiTF. On the other hand the salt dissociation was also promoted by the free non bonded –OH moieties present in some of the studied samples. Additionally, an influence of salt on the process of matrix formation was observed. The chemical reaction of MAO with oligoglycols was inhbited by the presence of the salt probably owing to complex formation occurring between MAO and LiTF. Nevertheless, the long time observation proved that after some weeks of storage the completion of the reaction is achieved.
Diploma typeDoctor of Philosophy
Author Maciej Marczewski (FC)
Maciej Marczewski,,
- Faculty of Chemistry
Title in PolishMetyloalumoksany jako komponenty hybrydowych kompozytów polimerowych
Languagepl polski
Certifying UnitFaculty of Chemistry (FC)
Disciplinechemical engineering / (chemical sciences domain) / (physical sciences)
Defense Date18-06-2010
End date29-06-2010
Supervisor Antoni Pietrzykowski (FC / DCOC)
Antoni Pietrzykowski,,
- Department Of Catalysis And Organometallic Chemistry

Internal reviewers Zbigniew Florjańczyk (FC / CPCT)
Zbigniew Florjańczyk,,
- Chair Of Polymer Chemistry And Technology
External reviewers Janusz Zakrzewski
Janusz Zakrzewski,,
-
Pages166
Keywords in Englishxxx
Abstract in EnglishThe aim of the presented work was the use of methylalumoxanes as components of hybrid organic-inorganic materials. The work can be divided into three main parts. The first part correspond to the research on the possibility of functionalization of methylalumoxane molecule by compounds containing hydroxyl group (alcohols, polyethylene glycols). In this part several reactions between methylalumoxane and various alcohols (methanol, ethanol, isopropanol, n-butanol) and polyethylene glycol at various molar ratios were investigated. Obtained results show that methylalumoxane can be used as a precursor of hybrid systems. The second part of presented work is devoted to the urea–urethane elastomers which were synthesized in a polyaddition reaction of ethylene oligoadipate (OAE) (an average molecular weight 2000) with bis(4-isocyanatephenyl)methane (MDI). Dicyandiamide was used as a chain extender. In order to obtain hybrid nanocomposites, OAE was modified by the reaction with methylalumoxanes (MAO) prior to use. The excess of active methyl groups of MAO was deactivated by reactions with alcohols or alkylphosphates. This method allowed to introduce nanosized aluminum-oxide based moieties into the polyurethane. The content of nanoparticles was equal to 3 wt. %. The aim of this part of my PhD thesis was to synthesize a homogeneous molecular dispersion of aluminum-oxide units in order to obtain urea–urethane nanocomposites with a higher fire resistance and improved mechanical properties. Microstructure of the nanocomposites was studied using high resolution scanning electron microscopy (HRSEM). Mechanical properties were examined by standard testing procedures. Flammability tests were also performed using a cone calorimeter under heat flux equal to 50 kW/m2. The results of the microstructure studies show even distribution of the nano-sized aluminum-oxide units in the polyurethane bulk. An increase of such properties as Young’s modulus and hardness, accompanied by a significant decrease in the heat release rate was observed. The third part of the presented work corresponds to the synthesis of hybrid composite polymer electrolytes. The systems studied based on the MAO organometallic precursor can be divided into three main groups. In the first one, the product of the reaction of monocapped oligoether (of various Mw being in range 350 to 1000 g/mol) with MAO was used as the only constituent of the polymeric matrix. In this case the samples were characterized not only by changing molecular weight of the organic compound but also by the varying amount of Al-CH3 moieties undergoing the reaction with the –OH groups. In the second case the reaction was carried out in two steps. The second group of electrolytes was obtained in a reaction of a branched system with PEG molecules containing two –OH moieties – in this situation PEG acted as a crosslinking agent. Contrary to the first case where a viscous liquid was formed, in the later case the consistency of the sample varies from liquid through rubbery to brittle solid depending on the Mw of the organic compounds and the sample composition. In the third case a polymer blend was obtained by mixing PEGDME (Mw = 500 g/mol) with the product of a reaction of MAO with PEGME (Mw = 350 g/mol). In this case the first oligoether compound did not contain in its structure any free –OH moieties and, in consequence, did not take part in chemical interactions with the MAO molecule. In all the cases two lithium salts (LiClO4 and LICF3SO3) were added to the system. On the basis of obtained results I can report the formation of a new type of hybrid organic-inorganic composite polymeric electrolyte. The novelty is based on the fact that the organometallic precursor used formed a nanosized Al-O cage itself. Thus, in consequence, a system was created being intermediate between typical nanocomposites with mechanically dispersed filler grains and materials obtained previously by the sol-gel type of reaction. This system was characterized by electrical, thermal and mechanical properties which can be easily tailored by an appropriate choice of branching and cross-linking oligoglycols, molecular weight and molar ratio between nanocores and both reactants. FTIR experiments reveal slightly improved salt dissociation in the electrolyte containing MAO whose properties can be correlated with improved cationic transference numbers measured for electrolytes containing LiTF. On the other hand the salt dissociation was also promoted by the free non bonded –OH moieties present in some of the studied samples. Additionally, an influence of salt on the process of matrix formation was observed. The chemical reaction of MAO with oligoglycols was inhbited by the presence of the salt probably owing to complex formation occurring between MAO and LiTF. Nevertheless, the long time observation proved that after some weeks of storage the completion of the reaction is achieved.
Thesis file
Marczewski.pdf 6.19 MB
Citation count*5 (2020-09-18)

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