Polyacrylamides (PAMs) are a class of polymers formed from acrylamide alone or copolymerized with other monomers. PAMs have been used in drinking water treatment as flocculants or coagulants in the highest volume among all the polymer types. In potable water treatment processes, polyacrylamides are often exposed to oxidants (e.g. chlorine and permanganate) and UV irradiation from sunlight or artificial sources. The purpose of this study is to evaluate the possible degradation of PAMs caused by chemical oxidation and/or UV irradiation. Three types of PAM products (nonionic, cationic and anionic) were studied under free chlorine and permanganate oxidation, UV irradiation, and their combined effects. It has been found that the cationic PAM was the most unstable polymer among the three types of polymer sample studies, however, only partial degradation was observed. Acrylamide residual in the cationic PAM C-3280 was higher than the U.S. guideline value, and exposure to either chlorine or permanganate resulted in decline of acrylamide level to some extent. UV irradiation did not cause reduction of total polymer contents and acrylamide residuals, but did accelerate chemically induced degradation. Exposure to chlorine or permanganate for one hour resulted in about 20-35% loss in flocculation performance for each polymer sample. Short time exposure (5 minutes) did not result in loss of flocculation performance for the nonionic and anionic PAMs. However, for the cationic PAM, even short time exposure to chlorine led to loss of flocculation performance of 25-35 %, which indicated that the cationic PAM was more susceptible to oxidation.

This research is to synthesize PANI (polyaniline) thin film for polymer organic solar cells as a hole transport layer on the top of ITO substrate by using electrochemical (cyclic voltammetry) method. The device structure is ITO (150 nm) / PANI (50 nm) / P3HT: PCBM (100 nm) / Al (200 nm). We investigated surface morphology, conductivity, and light transmission of the PANI thin film from different aniline monomer concentration and studied the factors on device efficiency, also compared with the device structured with hole transport layer PEDOT:PSS. In this study, we found PANI thin films synthesized with different aniline monomer concentration, their light transmission over 80% at the range of 450 nm ~ 650nm wavelength and the conductivity up to 0.6 S/cm. It shows that PANI thin film suitably act as hole transport layer. In addition, we found morphology of PANI thin film that varied with different aniline monomer concentration. The power conversion efficiency of the device mainly affected by morphology with different aniline monomer concentration. Comparing to other parameters of concentration, the 0.3M aniline monomer concentration polymerized PANI thin film owned the most appropriate surface morphology, and the power conversion efficiency up to 1.76%.

In this research that we design in the polymer structure containing the core monomer into benzene ring structure for appied on the flexible substrate and the optoelectronic components .Three novel bisphenol monomers have been synthesised successfully and converted to a series of poly(arylene ether)s by nucleophilic displacement reaction with Bis(4-fluorophenyl) sulfone, then we called them:P1, P2 and P3.We can see from the material structure that the steric hindrance of the group connected to the side of the main chain (M2) is larger than the group in the main chain(M1,M3),and the steric hindrance of the longer length of main chain (M3) is smaller than the shorter one(M1) in the polymerization Thermal analysis physics studies with these polymers confirmed by Thermogravimetric analyzer(TGA) and differential scanning calorimetry (DSC).It is indicated that Td5% of these polymers were 476¢XC~577¢XC in TGA and Tg of these polymers were 264¢XC~290¢XC in DSC. Besides, these polymers were not observed apparent crystallizing point, so we consider that they are not crystallized easily. The transmission spectra of thin film in the visible light region were up to 87%~93%. In drop shape analysis system, the contact angles of them are 85¢X~87¢X, show that they have good hyrophobicity.By above material properties of these polymers, they have high thermal stabilities, high optical transparency and good hydrophobicity.

Alginates are copolymers of &beta / -D-mannuronic (M) and &alpha / -L-guluronic acids (G). In this study, Azotobacter vinelandii ATCC&reg / 9046 was used to produce alginate in a fermentor. The effect of parameters such as dissolved oxygen tension (DOT), agitation speed, initial concentrations of sucrose and calcium on the properties of alginate were examined. Changes of DOT in the range of 1 and 10 % affected alginate production. The optimum DOT giving high alginate yield (4.51 g/L) and maximum viscosity was observed as 5 % yielding moderate GG-blocks of 55 %. Both high and low agitation levels reduced alginate production, but these conditions increased GG-block alginates as 76 and 87 % at 200 and 700 rpm, respectively. Moderate sucrose and calcium concentrations, 20 g/L and 50 mg/L, respectively were found better since further increase in their concentrations did not lead to a considerable improvement in alginate production and quality. Sodium alginates produced in this work were investigated for maximum heavy metal uptake with a special focus on copper ion and the highest copper uptake was around 1.9 mM Cu2+/g alginate. Findings showed that the block distribution of alginate was not as important as expected for copper removal. Alginate together with calcium ions was used for the removal of turbidity. The amount of GG-block was found to be important in turbidity removal. Alginate having 55 % GG block and 8.9 cP viscosity resulted in a final turbidity lower than 1 NTU at 2 mg/L of alginate with 60 mg/L of calcium ion.

This dissertation is focused on understanding heterogeneous bimetallic catalysts using model catalyst systems, such as Pd-Au/Mo(110), Pd/Au(111) and Pd/Au(100). Monometallic and bimetallic model catalysts, composed of Pd and Au, were prepared by physical vapor deposition (PVD) onto well-characterized metal substrates. Subsequent characterization was performed using an arsenal of modern surface science tools: low energy ion scattering spectroscopy (LEISS), infrared absorption spectroscopy (IRAS), temperature programmed desorption (TPD), and x-ray photoelectron spectroscopy (XPS). Electronic, morphological, and chemical properties of the prepared model catalysts were compared to those observed from monometallic single-crystal model catalysts such as Cu(100), Pd(111), Au(100), and Au(111). Between 700 K and 1000 K, formation of stable alloy surfaces of Pd-Au mixtures on Mo(110) was accompanied by substantial enrichment in Au. Annealing a 1:1 Pd-Au mixture at 800 K yields a Pd0.2Au0.8 surface alloy; the concentration of isolated Pd sites in this surface alloy can be systematically controlled by a judicious selection of initial bulk Pd-Au concentration. Pd-Au catalysts supported on Au(111) and Au(100) substrates generated a surface ensemble of Pd monomers surrounded by Au after annealing the systems at or above 550 K. To test the activity and selectivity of the prepared bimetallic model catalysts, the formation rate of vinyl acetate monomer (VAM) was examined. More significant enhancement of VAM formation rate was observed for bimetallic catalysts supported on Au(100) compared to those on Au(111). A critical surface ensemble composed two non-contiguous Pd monomers was proposed for the VAM synthesis. Oxygen plays a critical role in the efficiency of the synthetic route. Structure-reactivity correlations were established based on the suggested elementary reactions leading to the oxidative coupling of ethylene and acetic acid to form VAM.

A series of 3-(p-X-phenyl) thiophene monomers (X= –H, –CH3, – OCH3, –COOC2H5, –COCH3,–NO2) was electrochemically polymerized to furnish polymer films that could be reversibly reduced and oxidized (n- and p-doped). The oxidation potentials of the monomers and formal potentials of the n- and p-doping processes of polymers were correlated with resonance and inductive effects of the substituents on the phenyl ring as well as the semiempirically calculated heats of formation of the monomer radical cations. Moreover, the oxidation potentials of the monomers were correlated with the ionization potentials of the monomers calculated using density functional theory. The reactivity for coupling reactions and the major regioselective products of the polymerization reaction of mono- and oligo-3-phenylthiophenes are inferred from the calculated lone electron spin densities of the respective radical cations. The ionization potentials, which correspond to the energies for generating radical cations during oxidative processes were estimated.

Safripol is a South African polymer company producing mainly high density polyethylene and polypropylene for the South African market. Safripol used to be part of a global chemical company Dow Chemicals. Dow Chemical's divested in South Africa in 2006 and Safripol lost all the advantages of being part of a global corporate enterprise. The company is faced with a unique situation in that it is receiving monomer from Sasol, which is also its main competitor in the polymer market. The price of monomer and its low availability is putting pressure on Safripol's product margins, with a negative effect on the company's sustainability. The above was also defined as the research problem that threatens to undermine the company's competitive edge in the polymer market. It was clear from this research study that monomer and specifically propylene was the biggest burning point for Safripol regarding the price and availability thereof. Research into the South African polymer market has shown that Safripol will lose significant market share if the company is not showing additional growth in the market. The research problem is investigated through interviews, monomer availability investigations, plant capacity increasing and potential technology partner's discussions. A specific scenario planning process was also followed to help Safripol identify potential present and future scenarios that the company can investigate. The research problem was addressed by developing a strategy for Safripol to address the research objectives. Recommendations were done regarding the following: 1) Recommendations for additional propylene supply. 2) Recommendations to increase the polypropylene plant capacity. 3) Recommendations with regards to technology partners. 4) Recommendations regarding the scenario planning process. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2011. (Mag eers in 2014 gepubliseer word)

Safripol is a South African polymer company producing mainly high density polyethylene and polypropylene for the South African market. Safripol used to be part of a global chemical company Dow Chemicals. Dow Chemical's divested in South Africa in 2006 and Safripol lost all the advantages of being part of a global corporate enterprise. The company is faced with a unique situation in that it is receiving monomer from Sasol, which is also its main competitor in the polymer market. The price of monomer and its low availability is putting pressure on Safripol's product margins, with a negative effect on the company's sustainability. The above was also defined as the research problem that threatens to undermine the company's competitive edge in the polymer market. It was clear from this research study that monomer and specifically propylene was the biggest burning point for Safripol regarding the price and availability thereof. Research into the South African polymer market has shown that Safripol will lose significant market share if the company is not showing additional growth in the market. The research problem is investigated through interviews, monomer availability investigations, plant capacity increasing and potential technology partner's discussions. A specific scenario planning process was also followed to help Safripol identify potential present and future scenarios that the company can investigate. The research problem was addressed by developing a strategy for Safripol to address the research objectives. Recommendations were done regarding the following: 1) Recommendations for additional propylene supply. 2) Recommendations to increase the polypropylene plant capacity. 3) Recommendations with regards to technology partners. 4) Recommendations regarding the scenario planning process. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2011. (Mag eers in 2014 gepubliseer word)

This dissertation presents the synthesis of a series of well-defined multiresponsive hydrophilic ABA linear triblock copolymers and the study of their aqueous micellar gels. By incorporating a small amount of stimuli-responsive groups into thermosensitive outer blocks of ABA triblock copolymers, the lower critical solution temperatures (LCST) of thermosensitive blocks can be modified by external stimuli. Consequently, the sol-gel transition temperatures (Tsol-gel) of their aqueous solutions can be altered. Chapter 1 describes the synthesis and solution behavior of a series of thermo- and light-sensitive triblock copolymers, poly(ethoxytri(ethylene glycol) acrylate-co-o-nitrobenzyl acrylate)-b-poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-o-nitrobenzyl acrylate), with different contents of light-responsive o-nitrobenzyl groups. Aqueous solutions of these block copolymers with a 10.0 wt% concentration exhibited thermo-induced sol-gel transitions. Upon UV irradiation, the hydrophobic o-nitrobenzyl groups were cleaved, resulting in an increase in the LCST and consequently gel-to-sol transitions. The UV-irradiated solutions again underwent temperature-induced sol-gel transitions but at higher temperatures. The change of Tsol-gel was, in general, larger for the copolymer with a higher o-nitrobenzyl content after UV irradiation. Chapter 2 presents the synthesis of thermo- and enzyme-responsive ABA triblock copolymers, poly(ethoxydi(ethylene glycol) acrylate-co-4-((dihydroxyphosphoryl)oxy)butyl acrylate)-b-poly(ethylene oxide)-b-poly(ethoxydi(ethylene glycol) acrylate-co-4-((dihydroxyphosphoryl)oxy)butyl acrylate), and the enzyme-induced formation of thermoreversible micellar gels from their moderately concentrated aqueous solutions at 37 °C. The dephosphorylation by acid phosphatase decreased the LCST of thermosensitive outer blocks from above to below 37 °C. The enzyme-induced gelation of 7.9 wt % aqueous polymer solutions at pH 4.4 was monitored by rheological measurements. The Tsol-gel decreased and the gel strength increased with the increase of reaction time. The gels formed were thermoreversible. Chapter 3 presents the synthesis of two thermo- and pH-sensitive tertiary amine-containing ABA triblock copolymers and the sol-gel transitions of their aqueous solutions with a 10 wt% concentration at different pH values. Chapter 4 describes the use of reversible addition-fragmentation chain transfer (RAFT) polymerization for the synthesis of well-defined thermosensitive polymethacrylates and polyacrylates. Eight chain transfer agents were synthesized. The RAFT polymerizations of alkoxyoligo(ethylene glycol) (meth)acrylates using these chain transfer agents were well controlled, producing well-defined polymers. A summary of this dissertation research and future work are presented in Chapter 5.

Resumo: O objetivo deste estudo foi estabelecer, inicialmente, um método analítico em CLAE, para comparar o conteúdo de monômero residual de uma resina autopolimerizável para reembasamento imediato (Duraliner II - D) e uma resina termopolimerizável utilizada na confecção de bases de próteses (Lucitone 550 - L). Além disso, foi avaliado o efeito de dois tratamentos térmicos sobre esse conteúdo. Os monômeros utilizados como padrões foram o MMA (resina L) e o BMA (resina D). As condições cromatográficas para a análise foram: coluna ODS (15,0 x 0,46 cm), com 5 mm de tamanho de partícular e 100 Å de tamanho de poro, fase móvel ACN : H2O (55%: 45%) + 0,01% TEA, fluxo 0,8 mL/min, l 230 nm, volume de injeção 100 mL. As resinas foram proporcionadas e polimerizadas de acordo com as instruções dos fabricantes. Os corpos-de-prova (n = 18) dos dois materiais foram divididos em 3 grupos, com 6 corpos-de-prova cada. O grupo I (GI) não foi submetido a nenhum tratamento (controle). Para o grupo II (GII), os corpos-de-prova foram irradiados com microondas, a 550 W por 3 min para o material L e a 650 W por 4 min para o material D. Para o grupo III (GIII), os corpos-de-prova dos materiais L e D foram submetidos ao tratamento térmico por imersão em água a 55oC por 60 min e 10 min, respectivamente. Cada corpo-de-prova foi, então, fragmentado e submetido ao procedimento de extração em MeOH por 2 horas. Os valores de conteúdo de monômero residual foram transformados em porcentagem e analisados pelo teste de Kruskall-Wallis, ao nível de confiança de 99%. Em todos os grupos avaliados, o material D apresentou valores médios de monômero residual (GI - 0,87%; GII - 0,71%; GIII - 0,52%) significativamente maiores (p<0,01) que o material L (GI - 0,09%; GII - 0,06%; GIII - 0,05%). De acordo com a metodologia utilizada neste estudo, foram obtidas as seguintes conclusões: 1) O método ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to firstly establish an analytical method, which was the most satisfactory with reference to optimization of chromatographic conditions for HPLC. The method was then used to compare the residual monomer content in one hard chair-side reline resin (Duraliner II - D) and one heat-polymerized denture base resin (Lucitone 550 - L). Also, it was investigated the effect of two after polymerization heat-treatments on this residual monomer content. The HPLC operating conditions established were column ODS (15.0 x 0.46 cm), with 5 mm particles, mobile phase - 55% ACN : 45% deionized distilled water, flow injection rate - 0.8 mL/min., wave length detection - UV 230 nm, amount of sample solution injection 100 mL. Calibration curves were produced using standard solutions containing known amounts of each monomer evaluated (MMA - L; BMA - D) in mobile phase. The materials (D and L) were mixed and polymerized according to the manufacturer's instructions. Specimens (n = 18) of both materials were then divided into three groups, of six specimens each. Group I specimens were left untreated (GI - control). Specimens of group II (GII) were given heat treatment by microwave irradiation with 550 W for 3 min for material L and 650 W for 4 min for material D. For group III (GIII), L and D specimens were submitted to a heat-treatment by immersion in water at 55oC for 60 min and 10 min, respectively. Each specimen were cut into small pieces and subjected to an extraction procedure in methanol for 2 hours. The residual monomer content was then expressed as a percentage of residual monomer in the specimen. The percentage residual monomer data were analyzed by non-parametric Kruskall-Wallis test, at 99% level of confidence. In all groups evaluated, material D showed significantly higher (p<0.01) residual monomer mean values (GI - 0.87%; GII - 0.71%; ...(Complete abstract, click electronic access below) / Orientador: Ana Lucia Machado / Coorientador: Quezia Bezerra Cass / Banca: Carlos Eduardo Vergani / Banca: Neila Maria Cassiano / Mestre