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Styrene-butadiene rubber (SBR) copolymer nanosized latex particles were synthesized via differential microemulsion polymerization (DMP) in a 300ml bench-scale semi-batch reactor, equipped with a thermocouple and a magnetic four-blade stirrer. This approach employed a continuous and slow addition of styrene and butadiene monomers drop-wise into a continuous aqueous phase comprising DI water, an initiator, a surfactant and a chain transfer agent. It was found that this approach offered an efficient heterogeneous phase path to synthesize styrene-butadiene copolymer latices with a high-butadiene-level of the resulting latex particles. The latex nanoparticles were formed as the SBR copolymer monomers undergo a self-assembly process in the continuous phase and were stabilized by their surrounding surfactant particles. The size of the latex particles could be easily adjusted by alternating the monomer addition speed, the reaction temperature, the amount of chain transfer agent applied and the type and the amount of surfactant introduced in the process. Not surprisingly, a small amount of chain transfer agent introduced into the DMP system might facilitate micellar nucleation and reduction of gel content in the polymer dramatically and may also aid increasing the size of the SBR latex particles. Owing to the small size of SBR latices prepared by the DMP method, the glass transition temperature (Tg) of the latices is much lower than the SBR latices generated by conventional technique. Furthermore, the increase of Tg was observed with an increase of the SBR particle size.

An investigation was carried out to discover the effects of high conversion on the kinetic rate coefficients for the polymerisation of styrene. In such regimes, the reaction medium is of such high viscosity that these coefficients (kp and kt) exhibit profound changes. The changes were investigated with respect to the viscosity of and volume fraction of polymer present in the reaction medium. To circumvent the need to polymerise the monomer from the zero conversion, pre-formed polystyrene of known molecular weight was dissolved in purified styrene monomer. The resulting viscous solutions were then polymerised with AIBN as initiator. Effects on kp, kt and a reduction in f, initiator efficiency, were noted. Volume-fraction based models of termination kinetics were shown to be less applicable than one based on viscosity.

Polystyrene-co-4-hydroxystyrene ionomers (3.0-22 mol %) were synthesized via neutralization of demethylated polystyrene-co-4-methoxystyrene. The polystyrene-co-4-hydroxymethylstyrene ionomers (2.5-19.4 mol %) were prepared from the partial chloromethylation of polystyrene, followed by esterification, saponification, and finally neutralization. The physical properties of the ionomers as well as their nonionic precursors were studied by calorimetry, torsion pendulum and small-angle X-ray scattering (SAXS). Stress relaxation studies of the ionomers were also done. While evidence for ion aggregation was obtained for the styrene-4-hydroxystyrene ionomers from SAXS and torsion pendulum studies, no firm evidence was obtained for the styrene-4-hydroxymethylstyrene ionomers. Stress relaxation studies on both systems, however, showed failure of time-temperature superposition at high ion contents, indicating that these systems are both thermorheologically complex. The glass transition temperature of the matrix, the size of the ionic aggregates and the strengths of the ionic interactions within these large aggregates were related to the type and position of the ionic group.

Thesis (Ph. D.)--Lehigh University, 1998. / Includes vita. Includes bibliographical references.

Thesis (M.S.)--Rochester Institute of Technology, 1991. / Includes bibliographical references.

Thesis (Ph. D.)--Princeton University, 1930.

Thesis (Ph. D.)--Lehigh University, 1997. / Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1959) no. 12, p. 3261. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 228-233).

Orientador: Liliane Maria Ferrareso Lona / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-12T15:43:46Z (GMT). No. of bitstreams: 1 Galhardo_Eduardo_M.pdf: 2104513 bytes, checksum: 016e61e09855d8536628580f1a7c6e47 (MD5) Previous issue date: 2009 / Resumo: Polimerização via radical livre controlada, também conhecida como "pseudo-living radical polymerization" ou "Living Free Radical Polymerization" (LFRP) tem recebido cada vez mais atenção como uma técnica para produção de polímeros com micro estrutura altamente controlada. Em particular, distribuições de massas moleculares estreitas são obtidas, com polidispersidade muito próxima de um. Rotas convencionais para polímeros como estes têm sido polimerizações iônicas, no entanto, elas são extremamente sensíveis a impurezas e tipo de solvente. Desta forma, processos de polimerização via radical livre, que são muito mais versáteis e robustos a impurezas, para a produção de polímeros com estruturas controladas via processo "controlado" ou "pseudo-living", tem se tornado uma importante alternativa. Um dos desafios a ser enfrentado na polimerização controlada é o aumento da velocidade de reação, uma vez que as polimerizações controladas são muito mais lentas que as convencionais, em função da etapa de equilíbrio que ocorre na polimerização controlada, fazendo com que a cadeia polimérica crescente se encontre por longos períodos de tempo como polímero dormente. Neste projeto de pesquisa, foi feito um estudo em nível experimental (polimerização em ampolas) para investigar a polimerização controlada mediada por nitróxidos (NMRP, do inglês, Nitroxide Mediate Radical Polymerization), utilizando-se um peróxido trifuncional cíclico. Até hoje, só existem publicações em literatura que tratam da polimerização NMRP utilizando iniciadores monofuncionais (na maior parte das vezes, o iniciador BPO é utilizado com o controlador TEMPO) e difuncionais (desenvolvidos no próprio laboratório). Acreditava-se que o peróxido trifuncional possua a capacidade de aumentar a velocidade de polimerização, uma vez que mais radicais livres iniciais são gerados, se comparados com iniciadores monofuncionais. O efeito do valor da constante de dissociação do iniciador trifuncional na velocidade da reação foi analisado, assim como o efeito da recombinação dos grupos peróxidos, mais comuns em compostos cíclicos. / Abstract: Controlled free radical polymerization, also known as "pseudo-living radical polymerization" or "Living Free Radical Polymerization" (LFRP) has received increasing attention as a technique for the production of polymers with micro structure highly controlled. In particular, narrow molecular weight distributions, are obtained with polidispersidade very close to one. Conventional routes to produce polymers like this have been ions polymerizations, however, they are extremely sensitive to impurities and type of solvent. This radical polymerization, which are more versatile and robust to impurities, for the production of polymers with structures controlled, has become an important alternative. One of the challenges to be faced in the controlled polymerization is the increased speed of reaction, since the controlled polymerization is much slower that the standart free radical polymerization, due to the balance that occurs in controlled polymerization, in wich chain growing stay for long period of time as dormant polymer. In this research Nitroxide Mediate Radical Polymerization, using a trifunctional peroxide cyclic, will be done a studied in experimental level (ampoules polymerization). Literature reports NMRP process using monofunctional initiator (in most cases, the initiator BPO is used with the controller TEMPO) and bifunctional initiators (research developed by the LASSPQ Laboratory). It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated initialy, if compared with monofunctionais initiators. Furthermore, cyclic initiator might not form branches in chains, which prevents an increase in the polymer polidispersity. The effect of the dissociation constant for the trifunctional initiator in the reaction speed was analyzed, as well as the effect of the recombination of the peroxides groups, most common in cyclic compounds. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química