Issue 22, 2015

Stereocomplex formation in stereoblock copolymer networks composed of 4-armed star-shaped lactide oligomers and a 2-armed ε-caprolactone oligomer

Abstract

Stereoblock copolymer networks were prepared by reactions of methylenediphenyl 4,4′-diisocyanate (MDI) with hydroxy-terminated 4-armed star-shaped L-lactide and D-lactide oligomers (H4LLAO and H4DLAO) with the degree of polymerization per arm n = 15 in the presence and absence of a hydroxy-terminated 2-armed ε-caprolactone oligomer (H2CLO). Thermal and mechanical properties of the MDI-bridged stereoblock copolymer networks (MH-4scLAO/2CLOs 100/0, 75/25, 50/50, 25/75 and 0/100) were compared with those of a simple H4LLAO/H4DLAO blend (H4scLAO) and MDI-bridged homochiral (hc) networks of H4LLAO and H4DLAO (MH4LLAO and MH4DLAO). X-ray diffraction and differential scanning calorimetric analyses revealed that stereocomplex (sc) crystallites are formed without any hc crystallization for MH-4scLAO/2CLOs and H4scLAO, and that MH4LLAO and MH4DLAO are amorphous. The melting temperatures of sc crystallites for MH-4scLAO/2CLOs were much higher than those of hc crystallites of H4LLAO and H4DLAO, while the values were slightly lower than that of H4scLAO. Elongations at break and tensile toughnesses of MH-4scLAO/2CLOs (75/25, 50/50 and 0/100) were much higher than those of MH4LLAO and MH4DLAO.

Graphical abstract: Stereocomplex formation in stereoblock copolymer networks composed of 4-armed star-shaped lactide oligomers and a 2-armed ε-caprolactone oligomer

Supplementary files

Article information

Article type
Paper
Submitted
19 Mar 2015
Accepted
19 Apr 2015
First published
20 Apr 2015

Polym. Chem., 2015,6, 4123-4132

Author version available

Stereocomplex formation in stereoblock copolymer networks composed of 4-armed star-shaped lactide oligomers and a 2-armed ε-caprolactone oligomer

M. Shibata, M. Katoh, H. Takase and A. Shibita, Polym. Chem., 2015, 6, 4123 DOI: 10.1039/C5PY00401B

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