Polimerização radicalar de acetato de vinila mediada por novos complexos de Co(II) coordenados à bases de Schiff não simétricas
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Data
2019-06-25
Autores
Silva, Yan Fraga da
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Universidade Estadual Paulista (Unesp)
Resumo
Nas últimas décadas, a polimerização radicalar controlada (CRP) tem se tornado muito importante, pois permite a síntese de macromoléculas de arquiteturas específicas com um controle sobre as propriedades químicas e físicas. Sendo assim, este trabalho tem por objetivo a síntese de novos complexos de Co(II) coordenado a ligantes tipo Salen não simétricos. O precursor, os ligantes e os complexos foram caracterizados pelas seguintes técnicas: espectroscopia de absorção na região do UV-Vis, espectroscopia vibracional na região do infravermelho (FTIR), voltametria cíclica e Ressonância Magnética Nuclear (RMN 1H e 13C). Os complexos não simétricos contendo em sua composição aminas saturadas [CoII(CAYA 02)], [CoII(CAYA 03)] e o complexo contendo amina aromática [CoII(CAYA 04)] foram utilizados como mediadores na reação de polimerização radicalar controlada por organometálicos do acetato de vinila. Foram feitos estudos do efeito da temperatura na reação de OMRP (Polimerização Radicalar Mediada por Complexos Organometálicos) utilizando-se o complexo [CoII(CAYA 03)] sintetizado na razão molar de 1/3,25/542 (Co/AIBN/VAc). Após este estudo foram realizadas as cinéticas de polimerização para todos os complexos, pôde-se observar que cada complexo apresentou um perfil cinético de pseudo-primeira ordem com um aumento de Mn em determinados intervalos de tempo de acordo com a sua reatividade. Os complexos [CoII(CAYA 03)] e [CoII(CAYA 04)] apresentaram um aumento dos valores de Mn juntamente com a conversão mantendo os valores de polidispersidade (Ð) entre 1 e 1,5 que caracteriza o controle da reação. O complexo [CoII(CAYA 02)] apresentou valores de polidipersidade e Mn não correspondentes para um sistema controlado apresentados apresentando valores acima de 1,5.
In the last decades, controlled radical polymerization (CRP) has become very important because it allows the synthesis of macromolecules of specific architectures with a control over the chemical and physical properties. Thus, this work aims to synthesize new Co (II) complexes bound to non-symmetric Salen type ligands. The precursor, ligands and complexes were characterized by the following techniques: absorption spectroscopy in the UV-Vis region, infrared vibration spectroscopy (FTIR), cyclic voltammetry and Nuclear Magnetic Resonance (1H and 13C NMR). The non-symmetric complexes containing saturated amines [CoII (CAYA 02)], [CoII (CAYA 03)] and the aromatic amine-containing complex [CoII (CAYA 04)] were used as mediators in the radical polymerization reaction controlled by organometallic of vinyl acetate. It was studied the effect of temperature on the OMRP (Polymerization Radicalar Mediated by Organometallic Complexes) using the complex [CoII (CAYA 03)] synthesized in the molar ratio of 1 / 3.25 / 542 (Co / AIBN / VAc). After this study the polymerization kinetics were performed for all the complexes, it was observed that each complex presented a kinetic profile of pseudo-first order with an increase of Mn at certain time intervals according to their reactivity. The complexes [CoII (CAYA 03)] and [CoII (CAYA 04)] showed an increase of the Mn values together with the conversion maintaining the values of polydispersity (Ð) between 1 and 1,5 that characterizes the control of the reaction. The complex [CoII (CAYA 02)] presented noncorresponding polydipersity and Mn values for a controlled system presented values above 1.5.
In the last decades, controlled radical polymerization (CRP) has become very important because it allows the synthesis of macromolecules of specific architectures with a control over the chemical and physical properties. Thus, this work aims to synthesize new Co (II) complexes bound to non-symmetric Salen type ligands. The precursor, ligands and complexes were characterized by the following techniques: absorption spectroscopy in the UV-Vis region, infrared vibration spectroscopy (FTIR), cyclic voltammetry and Nuclear Magnetic Resonance (1H and 13C NMR). The non-symmetric complexes containing saturated amines [CoII (CAYA 02)], [CoII (CAYA 03)] and the aromatic amine-containing complex [CoII (CAYA 04)] were used as mediators in the radical polymerization reaction controlled by organometallic of vinyl acetate. It was studied the effect of temperature on the OMRP (Polymerization Radicalar Mediated by Organometallic Complexes) using the complex [CoII (CAYA 03)] synthesized in the molar ratio of 1 / 3.25 / 542 (Co / AIBN / VAc). After this study the polymerization kinetics were performed for all the complexes, it was observed that each complex presented a kinetic profile of pseudo-first order with an increase of Mn at certain time intervals according to their reactivity. The complexes [CoII (CAYA 03)] and [CoII (CAYA 04)] showed an increase of the Mn values together with the conversion maintaining the values of polydispersity (Ð) between 1 and 1,5 that characterizes the control of the reaction. The complex [CoII (CAYA 02)] presented noncorresponding polydipersity and Mn values for a controlled system presented values above 1.5.
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Palavras-chave
Ligantes não simétricos, Complexos de cobalto(II), Polimerização radicalar mediada por cobalto – CMRP, Non-symmetric ligands, Cobalt(II) complexes, Colbalt mediated radical polymerization – CMRP