Polymer Bionanocomposites Based on a P3BH/Polyurethane Matrix with Organomodified Montmorillonite—Mechanical and Thermal Properties, Biodegradability, and Cytotoxicity

In the present work, hybrid nanobiocomposites based on poly(3-hydroxybutyrate), P3HB, with the use of aromatic linear polyurethane as modifier and organic nanoclay, Cloisite 30B, as a nanofiller were produced. The aromatic linear polyurethane (PU) was synthesized in a reaction of diphenylmethane 4,4'-diisocyanate and polyethylene glycol with a molecular mass of 1000 g/mole. The obtained nanobiocomposites were characterized by the small-angle X-ray scattering technique, scanning electron microscopy, Fourier infrared spectroscopy, thermogravimetry, and differential scanning calorimetry, and moreover, their selected mechanical properties, biodegradability, and cytotoxicity were tested. The effect of the organomodified montmorillonite presence in the biocomposites on their properties was investigated and compared to those of the native P3HB and the P3HB-PU composition. The obtained hybrid nanobiocomposites have an exfoliated structure. The presence and content of Cloisite 30B influence the P3HB-PU composition's properties, and 2 wt.% Cloisite 30B leads to the best improvement in the aforementioned properties. The obtained results indicate that the thermal stability and mechanical properties of P3HB were improved, particularly in terms of increasing the degradation temperature, reducing hardness, and increasing impact strength, which were also confirmed by the morphological analysis of these bionanocomposites. However, the presence of organomodified montmorillonite in the obtained polymer biocomposites decreased their biodegradability slightly. The produced hybrid polymer nanobiocomposites have tailored mechanical and thermal properties and processing conditions for their expected application in the production of biodegradable, short-lived products for agriculture. Moreover, in vitro studies on human skin fibroblasts and keratinocytes showed their satisfactory biocompatibility and low cytotoxicity, which make them safe when in contact with the human body, for instance, in biomedical applications.