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Ring‐opening polymerization of degradable polyesters
Author(s) -
Stridsberg Kajsa,
Gruvegård Mats,
Albertsson AnnChristine
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.19981300131
Subject(s) - crystallinity , copolymer , polyester , polymerization , polymer chemistry , materials science , reactivity (psychology) , glass transition , amorphous solid , monomer , polymer , chemistry , organic chemistry , composite material , medicine , alternative medicine , pathology
Medium to high molecular weight random copolymers of 1,5‐dioxepan‐2‐one (DXO) and L‐lactide (L‐LA) or ε‐caprolactone (ε‐CL) of different compositions have been investigated. Polymerization was conducted in bulk at 110°C using stannous 2‐ethylhexanoate as catalyst. Poly(DXO‐co‐L‐LA) is a hydrolysable material with a glass transition temperature (T g ) ranging from −36 up to 58°C depending on the molar composition. The material exhibited crystallinity as long as the amount of DXO did not exceed 50 weight%. Reactivity ratios were determined to r L‐LA =10 and r DXO =0.1, giving a more blocky structure than expected in a random copolymer. The copolymer between ε‐CL and DXO was shown to be a truly random copolymer by 13 C NMR, as expected from the reactivity ratios, r DXO =1.6 and r ε‐CL =0.6. T g of the material was ranging from −64 up to −39°C. The ability of the poly(DXO‐co‐ε‐CL) to crystallize was retained up to a DXO content of 40 weight%. The melting temperature and crystallinity of both copolymers decrease with increasing amount of DXO. Incorporation of semicrystalline comonomers, L‐LA or ε‐CL, into the amorphous poly(DXO) creates materials with adjustable properties depending on the molar composition.