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

e-mail: semsarzadeh@modares.ac.ir

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.