Novel biodegradable polyurethanes reinforced with green nanofibers for applications in tissue engineering. Synthesis and characterization

Abstract

Abstract A new class of polyurethane (PU) biocomposites reinforced with green biocellulose nanofibers (BC) were designed and synthesized. These newly introduced non‐cytotoxic and biodegradable composites were synthesized with different ratios of hard to soft segments of the linear, aliphatic hexamethylene diisocyanate (HDI) and polycaprolactone diol (PCL), respectively. The porosity was introduced in the polyurethane matrix using a combination of salt leaching and thermally induced phase separation (TIPS). BC contents were in the range of 0–15 % of the final PU by weight. FTIR spectra showed complete conversion of HDI through the disappearance of the isocyanate and imine characteristic bands (at 2260 cm −1 and 1635 cm −1 , respectively) and appearance of carbonyl group band in PU (at 1730 cm −1 ). The hard to soft segment (i.e., HDI:PCL) ratios in the final PU polymer were quantified from 1 H Nuclear Magnetic Resonance (NMR) spectra by comparing the proton peaks arising for CH 2 CO at 2.25 ppm or OCH 2 at 3.9 ppm to CH 2 N at 2.9 ppm. Results showed that the ratios in the final product were consistent with the amounts added initially during the synthesis. Scanning electron microscope (SEM) images showed that porosity (57–75 %) were formed (pore size in the range of 125–355 µm), with an increase in pore content with the decrease in HDI:PCL content.