No description available.

Interest in using renewable raw materials to prepare biobased monomers, polymers, and materials is rapidly increasing. The goal of the research described is to develop branched polyesters of plant oil fatty acids, using different core pol yo ls (i.e. sucrose, dipentaerythritol, and tripentaerythritol) and plant oils (i.e. linseed, safflower, and soybean), into curing systems that have potential uses in applications such as coatings, composites, and adhesives. This study is mainly focused on the use of sucrose as the core polyol in the soyate resins. Sucrose esters and their derivatives have a compact structure, high density, and high functionality-double bonds, epoxides, or hydroxyls. When considering the use of sucrose ester compounds to form cross linked materials, the rigid core of sucrose can potentially impart hardness to the thermoset, and the high functionality can lead to rapid gelation and high cross link density. Thus, these novel biobased resins using sucrose esters of plant oils have the potential to be a significant advance in biobased resin technology, as well as to be competitive with the conventional petroleum-based resins.

High molecular weight soluble aromatic polybenzoxazoles (PBO) were synthesized from various bis( ortho amino phenols) and aromatic diacid chlorides via solution step polymerization in Nmethyl- 2-pyrrolidone (NMP). It was demonstrated that reaction temperatures of about 0 Cor lower were highly desired in order to obtain high molecular weight polyhydroxy amides. It was postulated that this lower temperature prevented pyridine catalyzed side reactions with the phenol group, which would otherwise either limit molecular weight or produce branched or gelled structures. The polyhydroxy amides were successfully solution cyclized at elevated temperatures (170 C) and complete cyclization was demonstrated with reactions times of 6 hours or less. The reSUlting fluorinated PBO materials were soluble in amide solvents at concentrations of at least 15% at 25 C. The PBO based on terephthaloyl chloride and the 6F bis(o-aminophenols) (2,2- bis(3 -amino-4-hydroxypheny I )-1,1,1-3,3,3-hexafluoropropane was systematically investigated. It was utilized as a thermally stable component of multiphase microphase separated block and graft copolymers. The second component investigated was based upon the thermally labile structure derived from polypropylene oxide (PPO). Block copolymers were prepared from either hydroxyl or aminophenyl terminated polypropylene oxide. The materials were characterized by solution, thermal and microscopic techniques. In particular, the potential of these materials to develop nanofoam-like structure was demonstrated. The resulting materials could be foamed by selectively degrading the labile block or graft at elevated temperatures in air. The foamed matrix was characterized via thermal and microscopic techniques and density values were compared to those of the homopolymer. It was concluded that the block copolymer produced nanofoam-like structures with pore sizes in the desired submicron range, but the graft copolymers appeared to collapse during the foaming process and were not further characterized. The resulting systems are of interest as an approach to lowering the dielectric constant of insulators, appropriate for microelectronic applications. The second portion of the thesis focused on cyanate ester or polycyanurate networks generated from dicyanate monomers. The influence of electron withdrawing and donating groups on the behavior of the network forming curing process was investigated. It was demonstrated that electron withdrawing characteristics, such as carbonyl, sulfone, or phenylphosphine oxide increased the reactivity of the cyanate group above the melting point of the monomer. Unfortunately, these electron withdrawing groups promoted a small processing 3window between the melting point and the exothermic cure temperature. However, by introducing an aryl ether bond, para or meta, to the cyanate group, wide highly desirable processing windows were demonstrated. In particular, the phenylphosphine oxide diphenyl ether combination produced good processabilty, cured glass transition temperatures of 280 C and high char yield in air, suggesting that the materials may show enhanced fire resistance. Adhesive bond strength of several materials were also investigated and it is suggested that future efforts in this area might be desirable. / Ph. D.

Paper and paperboard are the major constituents found in US landfills. Typically paper consists of 79% to 98% of lignocellulose which is considered to be the most abundant source of natural carbon on earth. Lignocellulose decomposition depends on the association of biodegradable cellulose and hemicellulose with lignin. Lignin is a recalcitrant material which hinders cellulose degradation in conventional landfills. Because of this property of lignin cellulose to lignin ratio (C/L) is a common landfill stabilization parameter. Refuse degradation in landfills is a microbiological process and is highly dependent on temperature, moisture, and pH. Bioreactor landfills are designed to enhance biodegradation of refuse by providing favorable conditions for microorganisms. Effect of elevated temperature and moisture on possibility of lignin degradation is studied in this work. Synthetic and newspaper lignin were preheated and then inoculated with anaerobically digested sludge. Newspaper in distilled water exposed to 95°C for 48 hours released 8 times more of solubilized lignin then non preheated newspaper. Moreover lignin monomers were detected as a result of 95°C pretreatment indicating the positive effect of high temperature on the providing lignin in more bioavailable form for microbes. Digested sludge inocula was found to be capable of lignin monomers degradation as well as low but significant mineralization of synthetic lignin with approximately 6% of carbon originated from lignin mineralized into methane and carbon dioxide. An exponentially increasing trend for lignin monomers solubilization as a function of temperature was observed for three types of substrate, synthetic lignin, cardboard, and newspaper with the highest rate of solubilization for newspaper. Results of this study suggest that some lignin degradation can occur at conditions typical for bioreactor landfills. / Master of Science

Activated dichloro- and difluoro- monomers are well known for the synthesis of high-performance polymeric materials through the use of aromatic nucleophilic displacement reactions. Here, novel activated difluoro monomers were synthesized using the well established chemistry of Reissert compounds. Difunctional bis(Reissert compound)s were synthesized by the reaction of 4-(pfluorobenzylisoquinoline) and trimethylsilyl cyanide with the following diacid chlorides: sulfonylbis(p-phenyleneoxy)dibenzoy chloride, oxybis (benzoyl chloride), and sulfonylbis(benzoyl chloride}. These aforementioned compounds were rearranged using NaH/THF to produce the desired diketones. Finally, difluorotetraketone monomers were produced by oxidation of the benzylic methylenes of the diketones. These reactions were evaluated by FTI R and 1 HNMR. These new activated heterocyclic difluorotetraketones are precursors to novel heterocyclic poly(ether ketones). / Master of Science

No description available.

Depuis une dizaine d'années, les polymères hyperbranchés sont apparus dans la littérature. Ils possèdent un grand nombre de branchements ainsi qu'un grand nombre de groupes terminaux. La structure globulaire des polymères hyperbranchés les empêche de former des enchevêtrements. Il en résulte un avantage décisif pour leur application sous forme de revêtement de surface: les polymères hyperbranchés ont une viscosité plus faible à l'état fondu que les polymères linéaires. Cela permet aisément de les étaler sous forme de films minces sans utiliser de solvant. De plus, les polymères hyperbranchés possèdent un grand nombre de groupes terminaux qui peuvent être fonctionnalisés avec des monomères photoréticulables.<p>Le but du travail de thèse est d'obtenir de nouveaux revêtements de surface, à partir de polymères hyperbranchés ou de polymères fortement branchés, qui trouveront leur application dans l'industrie chimique.<p><p>La thèse s'articule autour de trois chapitres de synthèse suivis d'un chapitre traitant de la photoréactivité des oligomères linéaires, fortement branchés, et hyperbranchés.<p><p>La première approche de synthèse envisagée est la copolymérisation alternante radicalaire. Divers maléimides ont été engagés dans des copolymérisations radicalaires avec des allyléthers sans succès. <p>Lorsque ces derniers sont remplacés par des vinyls éthers, une copolymérisation alternante est observée. Néanmoins, une importante irreproductibilité est constatée, certains batchs donnant lieu à une gélification.<p><p>La seconde voie de synthèse étudiée est l'approche classique de polycondensation de monomères de type AB2 .Le monomère AB2 est obtenu par addition de Michael de la diéthanolamine sur l'acrylate de méthyle. La polycondensation est concomitante avec l'acrylation des fonctions alcools. La compétition entre ces deux réactions limite les masses molaires accessibles bien que les réactions de transestérification soient catalysées par des dérivés du Zr et que la stoechiométrie ait été variée.<p><p>La troisième voie de synthèse se base aussi sur la réaction de Michael. Des oligomères fortement branchés sont obtenus à partir de 1,6-hexanedioldiacrylate et d'éthylènediamine. Leurs analogues linéaires sont synthétisés en remplaçant l'éthylènediamine par la propylamine. Lors de ces synthèses, il est apparu que les oligomères fortement branchés ont une viscosité supérieure à celle des oligomères linéaires!<p><p>Les oligomères hyperbranchés et acrylés, les oligomères linéaires et leurs analogues fortement branchés ont été étudiés du point de vue de leur photoréticulation sous rayonnement UV. Contrairement à ce qui était attendu, ils se sont montrés moins réactifs que les produits les plus performants de Cytec-Surface Specialties. Lors de cette étude, l'effet bénéfique des mines tertiaires sur l'inhibition par l'oxygène est apparu plus complexe que décrit dans la littérature. / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

A new class of &pi / -conjugated monomers was synthesized with combination of electron donating and electron-withdrawing heterocyclics to understand the effects of structural differences on electrochemical and optoelectronic properties of the resulting polymers. Electron deficient benzotriazole, substititued with benzyl from two available sites, coupled with stannylated electron donating groups, ethylenedioxythiophene (EDOT) and thiophene (Th), to yield four different monomers / 1-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3] triazole (BBTA), 2-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3] triazole (BBTS), 1-benzyl-4,7-bis(2,3-dihydrothieno[3,4-b]dioxin-5-yl)-2H-benzo [d][1,2,3]triazole (BBTEA), 2-benzyl-4,7-bis(2,3-dihydrothieno[3,4-b]dioxin-5-yl)-2H-benzo [d][1,2,3]triazole (BBTES). Furthermore, EDOT and thiophene terminated napthalene-2,3-crown ether containing monomers, 14,19-di(thiophen-2-yl)-naphtho[2,3-b][1,4,7,10,13] pentaoxacyclo pentadecane (TNCT), 14,19-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-naphtho[2,3-b][1,4,7,10,13]pentaoxacyclopenta decane (ENCE), were synthesized to observe the effect crown ether moiety on the final electrochemical and optoelectronic properties of resultant polymers. Cyclic voltammetry, UV-Vis-NIR spectroscopy and colorimetry techniques were employed to examine electrochemical and optoelectronic properties of all monomers and polymers. Experimental results showed that alteration of substituent, substitution position and donor groups&rsquo / strength lead to obtain polymers with different redox behaviors, optical band gaps and different number of achievable colored states.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: static density and magnetic structure functions of a melt of flexible polymers whose monomers possess bond-directed dipoles which interact with each other. In order to observe the effect of screening of the dipolar interaction on the structure functions we obtain results for cases with and without steric interactions and also for cases with and without Debye-H¨uckel screening of the dipole moments. / AFRIKAANSE OPSOMMING: Approximation” RPA) om die statiese digtheids- en magnetiese struktuurfunksies te bereken vir ’n smelt van hoogsbuigsame polimere, waarvan die monomere dipole langs die verbindings besit wat met mekaar in wisselwerking tree. Om die effek van afskerming op die dipolare wisselwerking en die struktuurfunksies te kan waarneem, bepaal ons resultate vir die gevalle met en sonder steriese wisselwerkings en ook vir gevalle met en sonder die Debye-H¨uckel afskerming van die dipoolmomente.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2005. / The primary focus of the research was the use of adamantane-containing molecules in polymer science. The research is divided into 2 parts, the first involving the syntheses of a new ligand for use in a metallocene catalyst system. The second part involved the synthesis of new monomers for the use in free radical polymerization systems, In the first part of the research, the synthesis of the ligand, 2-dimethyladamantylethylcyclopentadiene was attempted. This was done via the starting materials adamantylethylbromide and dimethylfulvene. In the first step the adamantylethylbromide was prepared via the tosylation reaction of admantaneethanol. Further, the use of either a Grignard or Barbier reaction to insert the 6,6 dimethylfulvene to yield the final product was attempted. The isolation of the final product could not successfully be completed, even though spectroscopic evidence suggested that the synthesis had been partially succssful. In the second part of the reasearch, the monomers 4-(1-adamantyl)phenolmethacrylate, adamantylmethylacrylate and admantylethylacrylate were synthesized. These monomers were homo-and copolymerized using a controlled radical reaction mechanism (RAFT).