Controlled free radical polymerization of vinyl acetate with cobalt acetoacetonate

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. Keywords. Co(acac) 2 catalyst; DMF ligand; bulk polymerization of vinyl acetate; capillary tube; controlled free radical polymerization.

Synthesis and Characterization of PDMS Based Triblock and Pentablock Copolymers

“…3.6 at −59°C [6,10]. PVAc and PSt segments exhibited T g values of 40 and 105°C [9,12,13], respectively for the The linear fit indicated that the concentration of propagating radical species is constant and radical termination reactions are not significant over time scale of the reaction. It was found that the molecular weights increase almost linearly with conversion, indicating that the number of chains was constant and the chain transfer reactions were rather negligible [16][17][18].…”

“…3.8 (Table 3.3). The growing peak of block copolymers remained monomodal throughout the reaction, indicating that all the unreacted attachable initiators have been removed prior to polymerization [9,13,[19][20][21]. Fig.…”

“…3.5. All signals of the 1 H-NMR spectra were assigned to their corresponding monomers and it can be declared that the synthesis of pentablock copolymers have proceeded successfully [12,13]. The 1 H-NMR of pentablock showed a signal at 0.0-0.2 ppm associated with CH 3 -Si methyl protons of PDMS along with the signals at 2.1-2.3 and 6.6-7.1 ppm corresponded to OCOCH 3 group from the PVAc segment and PSt segment respectively.…”

“…The 1 H-NMR of pentablock showed a signal at 0.0-0.2 ppm associated with CH 3 -Si methyl protons of PDMS along with the signals at 2.1-2.3 and 6.6-7.1 ppm corresponded to OCOCH 3 group from the PVAc segment and PSt segment respectively. Therefore, it is possible to synthesize the PDMS-based pentablock [12,13].…”

“…Therefore, it is possible to synthesize the PDMS-based pentablock copolymers via ATRP of monomers such as vinyl acetate and styrene in the presence of OH-PDMS-OH macroinitiator [12,13]. DSC thermograms of PDMS-based block copolymers are depicted in Fig.…”