Controlled free radical polymerization of vinyl acetate
with cobalt acetoacetonate
MOHAMMAD ALI SEMSARZADEH* and SAHAR AMIRI
Chemical Engineering Department, Polymer Group, Tarbiat Modares University,
P.O. Box: 14155/143, Tehran, Iran
Abstract. The polymerization of vinyl acetate with the complex catalyst of cobalt acetoacetonate [Co (acac)2]
and DMF ligand with benzoyl peroxide initiator has been successfully carried out in bulk and in solution. The
bulk polymerization has been used in a new route consisting of a one-step polymer formation in a fine capillary
tube. In this process, the high rate of propagation was used to carry out the reaction in a microcapillary tube.
Under 60°C, the colour-free reaction without solid catalyst impurity was 95% complete within a few hours.
The high molecular weight of polyvinyl acetate (PVAc) with its relatively low molecular distribution without
unreacted monomer provided a new method in microprocessing of the controlled radical polymerization of
vinyl acetate in a one-step polymerization process. PVAc polymerization systems showed induction time, which
was reduced in this reaction with using complex of DMF/ Co(acac)2. The kinetics of the reaction with a smaller
degree of branching from this catalyst indicated that the electronegativity of the transition metal and diffusion
of the homogeneous catalyst with DMF are important factors of fast polymerization in the bulk. Thermal
properties of the polymer indicated a lower glass transition state. The easily reformed or stretched microsolid
polymer demonstrated 20% crystallinity.
Graphical Abstract. Polymerization of vinyl acetate with the complex catalyst of Co(acac)2 and
DMF ligand with benzoyl peroxide initiator in bulk has been used in a new
route consisting of high molecular weight of polyvinyl acetate (PVAc) with its
relatively low molecular distribution without induction time. Thermal
properties of the polymer indicated a lower glass transition state.
Keywords. Co(acac)2 catalyst; DMF ligand; bulk polymerization of vinyl acetate; capillary tube; controlled
free radical polymerization.