Study of the photoluminescent properties of Polyurethane-CaCO₃ composites for bioapplications

Full text: Bio-based polyurethane (PU) polymers have emerged among materials due to their mechanical resistance and chemical inactivity, therefore, they have experienced a stupendous application enhancement in the biomaterials line[1]. The PU properties improvement can be achieved by the addition of nanocharges. Calcium carbonate (CaCO₃) charges are biocompatible. The strong birefringence presented by CaCO₃ allows it to be applied as an optical device because it has absorption bands in the infrared region, then, it has attracted the attention of researchers who believe that it is possible to use it in the manufacture of lasers[2]. Therefore, this work aims to study the morphological and luminescent properties of a bio-based PU, derived from castor oil, and its CaCO₃ doped version (PU-CaCO₃). The synthesis of the composites of PU and CaCO₃ were prepared by doping the PU matrix with 25% and 50% of CaCO₃ based on the PU mass. The materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Photoluminescence (PL) measurements. The results of XRD showed that Pu-CaCO₃ samples showed peaks related to the presence of CaCO₃ in the calcite phase (JCPDS: 5-586), proving the presence of carbonate in the PU matrix. All samples did not present secondary phases. SEM images showed that the pure PU samples presented a more homogeneous surface when compared to the materials containing CaCO₃, which presented surface with small agglomerates of small particles, which is an indicative of the presence of carbonate. The PL analysis showed that all samples have stronger emission peak at around 504-514 nm and a second emission peak at around 580 nm. These interesting results open new perspectives for optical applications of these materials. Reference 1 A. Cornille, R. Auvergne, O. Figovsky, B. Boutevin, S. Caillol, Eur. Polym. 87,535,2017. 2 F. J. Guillemin, J. Chetail, M. Research, 21, 557, 1987. (author)