Premium
Copolymers of 1.5‐dioxepan‐2‐one and L‐ or D,L‐dilactide ‐ synthesis and characterization
Author(s) -
Albertsson AnnChristine,
Löfgren Anders
Publication year - 1992
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19920530121
Subject(s) - copolymer , monomer , polymer chemistry , racemization , polymerization , reactivity (psychology) , carbon 13 nmr , viscometer , materials science , nuclear magnetic resonance spectroscopy , chemistry , polymer , organic chemistry , medicine , alternative medicine , pathology , viscosity , composite material
The copolymerization of 1,5‐dioxepan‐2‐one (DXO) with L‐ or D,L‐dilactide in bulk has been studied, using stannous‐2‐ethylhexanoate as the initiator. The copolymers were characterized using 1 H‐ and 13 C‐NMR spectroscopy, and DSC‐analysis. The molecular weight of the copolymers was measured by SEC, viscometry and light‐scattering techniques. The reactivity ratios of the copolymer system were calculated using the Kelen‐Tüdos method to be r 1 (DXO)=0,1 and r 2 (dilactide)=10. No racemization seems to have taken place during polymerization as shown by the absence of stereochemical splittings in the 13 C‐NMR spectra of the L‐dilactide homopolymer. The ability of the L‐LA/DXO copolymer to crystallize seems to be retained despite substantial amounts of 1,5‐dioxepan‐2‐one in the composition. 1 H‐ and 13 C‐NMR spectra indicate ring‐opening of the monomers by alkyloxygen cleavage.