KINETIC-MODEL OF PULSED LASER-INITIATED POLYMERIZATION IN THE PRESENCE OF CHAIN TRANSFER TO MONOMER

Taking account of chain transfer to monomer, the kinetics of pulsed la ser-initiated polymerization was treated in this article. The molecula r weight distribution function and the expressions of number- and weig ht-average degrees of polymerization for the resulting polymer were de rived under pseudostationary state conditions. Theoretical analysis an d numerical calculation demonstrate that the presence of monomer trans fer results in a narrower molecular weight distribution. With the incr easing chain transfer rate constant, the polydispersity index of the r esulting polymer decreases and finally approaches 2. Values of average degrees of polymerization and the polydispersity index vibrate betwee n maxima and minima periodically, and the amplitude of the vibration d eclines with the increasing monomer conversion. The molecular weight d istribution curves from numerical calculation show characteristic shar p peaks, and chain transfer to monomer weakens the intensity of peaks except the low molecular weight side one. Termination by combination l eads to a little narrower molecular weight distribution, and so does t he low concentration of the primary radical generated by per laser pul se.