Direct copolycondensation of ϵ-caprolactone with δ-valerolactone in the absence of catalysts

✍ Scribed by Kazumichi Imasaka; Tsuneji Nagai; Masaru Yoshida; Hironobu Fukuzaki; Masaharu Asano; Minoru Kumakura

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 336 KB
• Volume: 26
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(90)90153-u

✦ Synopsis

This reaction proceeds by direct condensation between two linear monomers, i.e. linear 6-hydroxycaproic acid and linear 5-hydroxyvaleric acid produced by hydrolysis of the cyclic CL and VL, respectively. It was found by ~H-NMR that the molar ratio in the copolymer is markedly different from that in the initial monomer mixture; the CL contents in the copolymers are ca 92, 78, 71, 53 and 19 mol% for initial CL contents in the feed of 85, 70, 50, 30 and 15 mol%, respectively. The crystallinities of the copolymers were determined by differential scanning calorimetry and X-ray diffraction. Each homopolymer had relatively high melting point but it showed a marked decrease by copolycondensation, reaching a minimum for equimolar composition of copoly(CL/VL). This effect is closely related to the distortion of crystal structure because of a rapid decrease in block lengths of -oxycaproyl and 6-oxyvaleryl units in the copolymer, the so-called sequence effects.