Mechanism of ring-opening polymerization of 1,5-dioxepan-2-one and L-lactide with stannous 2-ethylhexanoate. A theoretical study
2001 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 34, no 12, 3877-3881 p.Article in journal (Refereed) Published
A theoretical study of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepana-2-one (DXO) and (L)-lactide (LLA) with stannous(IE) a-ethylhexanoate (Sn(Oct)(2)) is presented. The B3LYP density functional method has been used for the quantum chemical calculations. Our results support a coordination-insertion mechanism initiated by a tin-alkoxide species formed prior to the ROP. The rate-determining step in the ROP was the nucleophilic attack of the alkoxide on the carbonyl carbon of the monomer. The activation energy for the ROP of DXO with Sn(Oct ')(2) has been determined to be 19.8 kcal/mol and for L-lactide 20.6 kcal/mol. At normal reaction temperatures, a ligand may dissociate as Oct 'H during propagation. An excess of carboxylic acid hinders the coordination of monomer to the initiating/propagating complex.
Place, publisher, year, edition, pages
2001. Vol. 34, no 12, 3877-3881 p.
density-functional theory, effective core potentials, gaussian basis functions, atomic basis sets, first-row atoms, molecular calculations, epsilon-caprolactone, tin(ii) octoate, ethylene polymerization, poly(ethylene glycol)
IdentifiersURN: urn:nbn:se:kth:diva-20680ISI: 000169049000014OAI: oai:DiVA.org:kth-20680DiVA: diva2:339376
QC 201005252010-08-102010-08-10Bibliographically approved