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Copolymerization of ϵ‐caprolactone and δ‐valerolactone
Author(s) -
Storey Robson F.,
Hoffman Douglas C.
Publication year - 1991
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.19910420115
Subject(s) - comonomer , copolymer , caprolactone , polymer chemistry , melting point , crystallinity , diol , depolymerization , materials science , composition (language) , chemistry , polymer , organic chemistry , linguistics , philosophy , composite material
Hydroxy‐terminated poly(ϵ‐caprolactone‐co‐δ‐valerolactone) (PCV) copolymers were synthesized by the diol initiated bulk copolymerization of ϵ‐caprolactone (C) and δ‐valerolactone (V). The two homopolymers were semicrystalline, with almost identical melting temperatures; copolymerization significantly lowered the melting point (T m ) compared to either homopolymer. Copolymer melting points were found to decrease with decreasing molecular weight and to be dependent on composition, i.e., the incorporation of a comonomer into either homopolymer resulted in a decrease in T m , with the maximum decrease occurring at a copolymer composition of about 60 mole‐% ϵ‐caprolactone. The molar composition of the copolyesters was determined from 13 C NMR spectra. At conversions> 50 % the copolymer composition was found to be richer in ϵ‐caprolactone than predicted from the integrated form of the first‐order Markov copolymer equation, suggesting that the depolymerization of δ‐valerolactone becomes important at high conversions and the addition of ϵ‐caprolactone is greatly favored regardless of the ultimate unit.