J. Baran et al., INTERMOLECULAR CHAIN TRANSFER TO POLYMER WITH CHAIN SCISSION - GENERAL TREATMENT AND DETERMINATION OF K(P) K(TR) IN L,L-LACTIDE POLYMERIZATION/, Macromolecular rapid communications, 18(4), 1997, pp. 325-333
A general kinetic treatment of the system with intermolecular chain tr
ansfer followed by fast reinitiation is given. It leads to the broaden
ing of the molecular weight distribution (MWD), the number of growing
chains being invariable. Thus, this system can be considered as a spec
ial case of living polymerization. A general method has been elaborate
d allowing the determination of the ratio of the rate constant of prop
agation (k(p)) to the rate constant of the bimolecular transfer (k(tr)
((2))) from the dependence of the MWD on monomer conversion. Numerical
values of k(p)/k(tr)((2)) equal to approximate to 10(2) and 25 were t
hus determined for the polymerization of L,L-lactide (L,L-dilactide) i
nitiated with aluminium tris(isopropoxide) trimer ({Al((OPr)-Pr-i)(3)}
(3)) and tributyltin ethoxide ((Bu3SnOEt)-Bu-n), respectively.