Crystallization Kinetics and Morphology of Biodegradable Double Crystalline PLLA-b-PCL Diblock Copolymers

• DOI: 10.1021/ma100201g
• Publication Date: 2010-04-09T16:34:00Z
• Authors: Reina Verónica Ca...; Alejandro J. Müller; Jean-Marie Raquez; Philippe Dubois
• Keywords: 02 engineering and technology; 0210 nano-technology

The crystallization kinetics and morphology of biodegradable and double crystalline poly(l-lactide)-b-poly(e-caprolactone) diblock copolymers (PLLA-b-PCL) was studied in a wide composition range by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM). The two blocks were found to be partially miscible according to the variations of their thermal transitions with composition. PLOM results showed that PLLA crystallizes in a wide composition range with a spherulitic superstructural morphology. Only when the PLLA content is as low as 10 wt % are axialites formed. These results were in good agreement with the overall crystallization kinetics obtained by DSC isothermal experiments and analyzed by the Avrami equation. Both overall crystallization rates and spherulitic growth rates of the PLLA block decrease with PCL content because PCL acts as a diluent for the PLLA block in view of their miscibility. Reorganization processes revealed as double melting peaks for the PLLA block (n...