Interactions In Blends Containing Alginate And Biodegradable Poly (E-Caprolactone)

Abstract

The phase behavior of blends containing the block copolymer alginate (ALG) and biodegradable poly( -caprolactone)s (PCL) with different molecular weights was analyzed. Blends were obtained by solution casting from acetic acid solutions (pH 4,2) and analyzed in terms of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and atomic force microscopy (AFM). The blends showed a single Tg value (intermediate to those of the pure components) over the whole range of compositions analyzed. This behavior could be interpreted as showing miscibility among the components over the whole range of compositions. TGA showed that the blends degraded at intermediate temperatures with respect to the pure components, probably due to interactions among them. Miscibility by interactions among the components was analyzed by FT-IR, showing that the bands corresponding to carboxyl groups of PCL and hydroxyl groups of ALG were displaced, which we attributed to a strong interaction by hydrogen bonding between them. AFM images of the mixtures showed a completely different

morphology when compared to that of the pure components, probably as a consequence of interactions and miscibility between them. Keywords: alginate, polymeric blends, phase behavior, biodegradable polymers, miscibility.