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A polimerizacao do estireno por ATRP foi conduzida usando os complexos Cp*RuCl(PPh3)2, e Cp*RuCl(P(4-CF3−C6H4)3)2 como catalisadores, a fim de avaliar a influencia das propriedades eletronicas dos ligantes fosfinas na velocidade e controle da polimerizacao. Os dados cineticos para polimerizacoes realizadas com Cp*RuCl(PPh3)2, mostram que os pesos moleculares aumentam linearmente com a conversao, com uma eficiencia media de iniciacao, de 0,77. Os pesos moleculares obtidos no estudo cinetico com Cp*RuCl(P(4-CF3−C6H4)3)2 tambem aumentam com a conversao, mas mostram um marcado desvio abaixo dos pesos moleculares teoricos. Este comportamento foi explicado pela oxidacao gradual, irreversivel do catalisador Cp*RuCl(P(4-CF3−C6H4)3)2, como confirmado pela espectroscopia de RMN de 31 P. O catalisador Cp*RuCl(PPh3)2 promove a polimerizacao com uma velocidade maior do que usando Cp*RuCl(P(4-CF 3 −C 6 H 4 ) 3 ) 2 , o que e consistente com as melhores propriedades de doacao de eletrons de PPh3 versus P(4-CF3−C6H4)3. Estudos preliminares da polimerizacao do estireno com ATRP em CO2 supercritico mostram que somente o catalisador Cp*RuCl(P(4-CF3−C6H4)3)2, com ligantes fluorados, e ativo. Styrene polymerization by ATRP was conducted independently using the complexes Cp*RuCl(PPh3)2, and Cp*RuCl(P(4-CF3−C6H4)3)2 as catalysts, in order to evaluate the influence of the electronic properties of the phosphine ligands on the rate and control of the polymerization. The kinetic data for polymerizations carried out with Cp*RuCl(PPh3)2, show that molecular weights increase linearly with conversion with an average initiation efficiency of 0.77. The molecular weights obtained in the kinetic study with Cp*RuCl(P(4-CF3−C6H4)3)2 also increase with conversion but show a marked deviation below the theoretical molecular weights. This behavior was explained by the gradual, irreversible, oxidation of catalyst Cp*RuCl(P(4-CF 3 −C 6 H 4 ) 3 ) 2 as confirmed by 31 P-NMR spectroscopy. Catalyst Cp*RuCl(PPh3)2 promotes the polymerization with a rate of polymerization higher than that obtained using Cp*RuCl(P(4-CF3−C6H4)3)2; this is consistent with the better electron donating properties of PPh3 versus P(4-CF3−C6H4)3. Preliminary studies of styrene polymerization by ATRP in supercritical CO2, shows that only catalyst Cp*RuCl(P(4- CF 3 −C 6 H 4 ) 3 ) 2 , with fluorinated ligands, was active.

Comparative study of the catalytic activity of the complexes Cp*RuCl(PAr3)2 [Ar = -C6H5 and 4-CF3-C6H4] in the ATRP of styrene