Thermodynamic and stereochemical aspects of the polymerizability of glycolide and lactide
Visualitza/Obre
thermodynamic.pdf (625,9Kb) (Accés restringit)
Sol·licita una còpia a l'autor
Què és aquest botó?
Aquest botó permet demanar una còpia d'un document restringit a l'autor. Es mostra quan:
- Disposem del correu electrònic de l'autor
- El document té una mida inferior a 20 Mb
- Es tracta d'un document d'accés restringit per decisió de l'autor o d'un document d'accés restringit per política de l'editorial
Cita com:
hdl:2117/17539
Tipus de documentArticle
Data publicació2012-03-01
Condicions d'accésAccés restringit per política de l'editorial
Llevat que s'hi indiqui el contrari, els
continguts d'aquesta obra estan subjectes a la llicència de Creative Commons
:
Reconeixement-NoComercial-SenseObraDerivada 3.0 Espanya
Abstract
The ring-opening polymerizations of the
dilactones glycolide and the S,S- and S,R-stereoisomers of
lactide were studied using quantum mechanical methods.
The ring strain and the conformational distribution of these
cyclic monomers and of the polymers were calculated, and
the effect of the medium on the polymerization was predicted,
for both bulk and solution. The polymerizability of
the three monomers in the gas phase, that is, nonpolar
medium, is much greater than that of d-valerolactone or
1,4-dioxan-2-one. This difference vanishes in the polar
medium chloroform, which is attributed to the fact that,
while all of these monomers possess polar cis-lactone
bonds, the three dilactones possess small dipole moments.
The data are combined to give polymerization enthalpy and
free energy values. The four stereoregular lactide polymers
did not differ significantly in energy. Accordingly, the
ability to synthesize any one of these rests on catalyst
specificity (‘‘polymer chain-end control’’). Although
introduction of sterically demanding methyl groups into
glycolide is expected to favor coiled conformations and
decrease polymerizability, this was not found to be the
case. Good agreement of calculated values with experimental
data from the literature was achieved.
CitacióAleman, C. [et al.]. Thermodynamic and stereochemical aspects of the polymerizability of glycolide and lactide. "Theoretical chemistry accounts", 01 Març 2012, vol. 131, núm. 3, p. 1881-1891.
ISSN1432-881X
Versió de l'editorhttp://link.springer.com/article/10.1007/s00214-012-1133-y
Fitxers | Descripció | Mida | Format | Visualitza |
---|---|---|---|---|
thermodynamic.pdf | 625,9Kb | Accés restringit |