Síntese e aplicação de complexos de cobalto(II) coordenados a ligantes tetraimínicos na polimerização radicalar de acetato de vinila mediada por organometálicos

Abstract

O trabalho reporta a síntese de dois novos complexos de cobalto(II), coordenados a ligantes tetraimínicos, estes foram denominados [Co(beb)](PF6)2 e [Co(bfb)](PF6)2. Os complexos foram caracterizados por Espectroscopia de Infravermelho (FT-IR), Espectroscopia de Ultravioleta-visível (UV-Vis) e Voltametria Cíclica (VC). A polimerização radicalar de acetato de vinila (VAc) foi iniciada pelo azobisisobutironitrila (AIBN) e realizada na presença de [Co(beb)](PF6)2 ou [Co(bfb)](PF6)2 como agentes controladores, a temperatura de 65 ºC. As massas moleculares de poliacetato de vinila (PVAc) foram analisadas por GPC e Cg.

This study describes the synthesis of two novel cobalt(II) complexes, coordinated to tetraimine ligands [Co(beb)](PF6)2 and [Co(bfb)](PF6)2, where beb = 1,2-diphenylethane-bis(N2 -benzylidene-N1 -methyleneethane- 1,2-diamine) and bfb = 1,2-diphenylethane-bis(N2 -benzylide-N1 - methylenebenzene-1,2-diamine). The complexes were characterized by FT-IR, UV-Vis and Cyclic Voltammetry. The radical polymerization of vinyl acetate (VAc) initiated by azobisisobutyronitrile (AIBN) was carried out under different reaction conditions in the presence of [Co(beb)](PF6)2 or [Co(bfb)](PF6)2 as mediators. The systematic variation of the reaction conditions, such as [initiator]/[Co] and [monomer]/[Co] molar ratios, affected the polymerization rates and the molecular weights, reaching a certain level of control. The [Co(beb)](PF6)2 complex was shown to be more efficient in controlling the polymerization of VAc when compared to the [Co(bfb)](PF6)2 complex.