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Intra‐ and intermolecular chain transfer to macromolecules with chain scission. The case of cyclic esters
Author(s) -
Penczek Stanislaw,
Duda Andrzej,
Szymanski Ryszard
Publication year - 1998
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19981320141
Subject(s) - macromolecule , chain (unit) , intermolecular force , bond cleavage , polymer chemistry , chemistry , chain scission , polymer science , materials science , organic chemistry , polymer , molecule , biochemistry , physics , catalysis , astronomy
Chain transfer to macromolecules with chain scission is the most often observed “side” reaction in the polymerization of heterocyclics. In our previous works we analysed quantitatively the intramolecular chain transfer to the own macromolecule (back‐biting). This paper gives a general treatment of the kinetics of polymerization with propagation and intermolecular chain transfer to macromolecules, accompanied with chain scission. The numerical solution developed allows determining the k p /k tr ratio from the dependence of m̄ w /m̄ n on monomer conversion. This treatment was applied to the polymerization of L,L‐lactide and k p /k tr ratios were measured for covalent alcoholate active species bearing Al, Fe, Ti, Sm, and La. In this way selectivities of active species (expressed with k p /k tr ) were for the first time measured and finally correlated with the atomic number of the corresponding metal atoms, related to the strength of the bond involved in the monomer addition.