Influence of Amorphous Block on the Thermal Behavior of Well-Defined Block Copolymers Based on -Caprolactone

MARIO D. NINAGO; ANGEL J. SATTI; ANDRÉS E. CIOLINO; MARCELO A. VILLAR

JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY

SPRINGER

Lugar: New York; Año: 2012 vol. 112 p. 1277 - 1287

1388-6150

In this work, we studied the thermal characterization of block copolymers based on å-caprolactone (CL). The copolymers were obtained by anionic polymerization techniques, using different co-monomers such as styrene (S) and dimetilsiloxane (DMS). The synthesized copolymers were characterizated by H-Nuclear Magnetic Resonance (1H-NMR), Size Exclusion Chromatography (SEC), and Fourier Transform Infrared Spectroscopy (FTIR). Isothermal crystallization was performed by Differential Scanning Calorimetry analysis (DSC), and Avrami?s theory was employed in order to obtain kinetics parameters of interest, such as the half-life for the crystallization process (t1/2), the bulk crystallization constant (k), and the Avrami?s exponent (n). The spherulitic grow was measured by Polarized Optical Microscopy (POM) in order to determine the crystallization behavior. Poly(å-caprolactone) block (PCL) crystallization was analyzed by considering the physico-chemical characteristics of the neighboring blocks, PS or PDMS. According to the data obtained, the chemical nature of the neighbor block in the PCL based copolymer affects the kinetics parameters of the Avrami?s equation, as can be deduced by comparing the experimental results obtained for pure PCL and the studied block copolymers. On the other hand, the apparent thermal degradation activation energies Ead for both, PCL and block copolymers, were determined by Ozawa?s method. The incorporation of PDMS instead of PS improves the stability of the resulting copolymer, as if was observed by Thermogravimetric Analysis (TG).