Eur. Phys. J. E (2007) 23: 295-303
https://doi.org/10.1140/epje/i2007-10191-6

Regular Article

Miscibility in poly(L-lactide)-b-poly(ε-caprolactone) double crystalline diblock copolymers

¹ Physics Department, Universidad Simón Bolıvar, Apartado 89000, 1080 A, Caracas, Venezuela
² Materials Science Department, Universidad Simón Bolıvar, Apartado 89000, 1080 A, Caracas, Venezuela
³ Laboratory of Polymeric and Composite Materials (LPCM), University of Mons-Hainaut, Place du Parc 20, 7000, Mons, Belgium

^* e-mail: elaredo@usb.ve;

Received: 29 March 2007
Accepted: 11 June 2007
Published online: 8 August 2007

Abstract

Thermally stimulated depolarization currents, TSDC, wide-angle X-ray scattering, WAXS, differential scanning calorimetry, DSC, and polarized light optical microscopy, PLOM, have been used to examine poly(L-lactide)-b-poly(ε-caprolactone) diblock copolymers in a wide composition range. Both components are crystallizable and the miscibility in the amorphous phase has been determined from the behavior of the primary relaxations which are the dielectric manifestation of the glass transition, and also from the superstructural morphology revealed by PLOM and the compositional dependence of the melting points as determined by DSC. Distinct segmental mobilities in the amorphous phase which can be well resolved by TSDC are present; the α mode of the slower component shifts to lower temperatures as the PCL content increases while the glass transition of neat PCL is present for all compositions. A relaxation times bimodal distribution is apparent for PCL-rich copolymers. The composition dependence of the multiple glass transitions detected in these weakly segregated copolymers are predicted by the self-concentration model for a miscible blend made of components with a large T_g contrast.